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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2012	Oct. 26, 2012
Entity Registrant Name	BERRY PETROLEUM COMPANY
Entity Central Index Key	0000778438
Current Fiscal Year End Date	--12-31
Document Type	10-Q
Document Period End Date	Sep. 30, 2012
Amendment Flag	false
Entity Filer Category	Large Accelerated Filer
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3
Class A
Entity Common Stock, Shares Outstanding		52,386,165
Class B
Entity Common Stock, Shares Outstanding		1,763,866

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 104	$ 298
Restricted short-term investments	125	65
Accounts receivable	114,916	115,952
Deferred income taxes	0	13,779
Derivative instruments	10,573	6,117
Assets held for sale	0	14,622
Prepaid expenses and other	15,503	16,801
Total current assets	141,221	167,634
Oil and natural gas properties (successful efforts basis), buildings and equipment, net	3,010,126	2,531,393
Derivative instruments	11,122	7,027
Other assets	30,891	28,898
TOTAL ASSETS	3,193,360	2,734,952
Current liabilities:
Accounts payable	155,766	126,489
Revenue and royalties payable	44,405	49,253
Accrued liabilities	48,392	35,066
Derivative instruments	1,309	20,365
Deferred income taxes	3,486	0
Total current liabilities	253,358	231,173
Long-term liabilities:
Deferred income taxes	248,018	185,450
Senior secured revolving credit facility	510,000	531,500
8.25% Senior subordinated notes due 2016	0	200,000
Asset retirement obligation	84,257	64,019
Derivative instruments	1,358	15,505
Other long-term liabilities	17,541	17,884
Total long-term liabilities	1,963,716	1,663,050
Shareholders' equity:
Preferred stock, $0.01 par value, 2,000,000 shares authorized; no shares outstanding	0	0
Capital in excess of par value	362,051	350,158
Accumulated other comprehensive loss	(1,736)	(5,517)
Retained earnings	615,429	495,549
Total shareholders' equity	976,286	840,729
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,193,360	2,734,952
Class A
Capital stock, $0.01 par value:
Common Stock	524	521
Class B
Capital stock, $0.01 par value:
Common Stock	18	18
10.25% Senior notes due 2014, net of unamortized discount
Long-term liabilities:
Senior notes	202,542	348,692
6.75% Senior notes due 2020
Long-term liabilities:
Senior notes	300,000	300,000
6.375% Senior notes due 2022
Long-term liabilities:
Senior notes	$ 600,000	$ 0

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2012	Dec. 31, 2011
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares outstanding	0	0
Class A
Capital stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	52,385,165	52,067,994
Common Stock, shares outstanding	52,385,165	52,067,994
Class B
Capital stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized	3,000,000	3,000,000
Common Stock, shares issued	1,763,866	1,797,784
Common Stock, shares outstanding	1,763,866	1,797,784
Common Stock, liquidation preference (in dollars per share)	$ 0.50	$ 0.50
8.25% Senior subordinated notes due 2016
Interest rate on debt instrument (as a percent)	8.25%	8.25%
10.25% Senior notes due 2014
Interest rate on debt instrument (as a percent)	10.25%	10.25%
6.75% Senior notes due 2020
Interest rate on debt instrument (as a percent)	6.75%	6.75%
6.375% Senior notes due 2022
Interest rate on debt instrument (as a percent)	6.375%	6.375%

Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Condensed Statements of Operations - USD ($) $ in Thousands	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
REVENUES
Oil and natural gas sales	$ 232,916	$ 225,325	$ 688,350	$ 643,474
Electricity sales	9,514	9,826	21,354	24,202
Natural gas marketing	1,939	3,612	5,378	11,282
Gain on sale of assets	170	0	1,770	0
Other income	286	463	1,678	1,394
TOTAL REVENUES	244,825	239,226	718,530	680,352
EXPENSES
Operating costs—oil and natural gas production	70,778	61,979	187,491	177,842
Operating costs- electricity generation	4,727	6,965	14,000	19,969
Production taxes	9,700	9,185	30,048	24,926
Depreciation, depletion & amortization			160,251	160,136
Natural gas marketing	1,753	3,285	4,917	10,475
General and administrative	17,767	14,922	53,473	47,123
Interest	20,572	19,928	61,446	53,295
Impairment of oil and natural gas properties	0	0	67	0
Dry hole, abandonment, impairment and exploration	2,729	196	7,283	619
Gain on purchase	0	0	0	(1,046)
Extinguishment of debt	0	14,391	41,545	14,391
Realized and unrealized loss (gain) on derivatives, net	28,287	(162,145)	(56,314)	(126,437)
TOTAL EXPENSES	215,661	23,774	504,207	381,293
Earnings before income taxes	29,164	215,452	214,323	299,059
Income tax provision	11,038	81,451	81,283	112,389
Net earnings	$ 18,126	$ 134,001	$ 133,040	$ 186,670
Basic net earnings per share (in dollars per share)	$ 0.33	$ 2.45	$ 2.41	$ 3.42
Diluted net earnings per share (in dollars per share)	0.33	2.42	2.39	3.38
Dividends per share (in dollars per share)	$ 0.08	$ 0.08	$ 0.24	$ 0.23
Oil and Natural Gas Properties, Buildings, and Equipment
EXPENSES
Depreciation, depletion & amortization	$ 58,887	$ 54,581	$ 158,869	$ 158,657
Electricity Generation
EXPENSES
Depreciation, depletion & amortization	$ 461	$ 487	$ 1,382	$ 1,479

Condensed Statements of Comprehensive Earnings - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net earnings	$ 18,126	$ 134,001	$ 133,040	$ 186,670
Other comprehensive earnings, net of income taxes:
Amortization of accumulated other comprehensive loss related to de-designated hedges, net of income tax benefits of $924, $5,886, $2,318 and $17,559, respectively	1,505	9,604	3,781	28,649
Other comprehensive earnings	1,505	9,604	3,781	28,649
Comprehensive earnings	$ 19,631	$ 143,605	$ 136,821	$ 215,319

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

Net of tax amount of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Statement of Financial Accounting Standard (FAS)
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
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-Subparagraph c(3)
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Condensed Statements of Comprehensive Earnings (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Amortization of Accumulated other comprehensive loss related to de-designated hedges, income taxes	$ 924	$ 2,318	$ 5,886	$ 17,559

- Definition

Tax effect of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

+ References + Details

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
Condensed Statements of Cash Flows - USD ($) $ in Thousands	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net earnings	$ 133,040	$ 186,670
Depreciation, depletion and amortization	160,251	160,136
Gain on sale of assets	(1,770)	0
Gain on purchase	0	(1,046)
Extinguishment of debt	6,842	3,377
Amortization of debt issuance costs and net discount	5,350	6,261
Impairment of oil and natural gas properties	67	0
Dry Hole and Impairment	2,515	316
Derivatives	(34,760)	(139,683)
Stock-based compensation expense	7,589	7,451
Deferred income taxes	77,511	105,096
Other, net	(1,620)	(275)
Allowance for bad debt	450	0
Change in book overdraft	7,573	5,359
Changes in operating assets and liabilities:
Accounts receivable	504	(24,614)
Inventories, prepaid expenses, and other current assets	(2,634)	(2,263)
Accounts payable and revenue and royalties payable	15,097	48,438
Accrued interest and other accrued liabilities	15,611	16,667
Net cash provided by (used in) operating activities	391,616	371,890
Cash flows from investing activities:
Exploration and development of oil and natural gas properties	(524,036)	(424,144)
Property acquisitions	(75,706)	(155,443)
Capitalized interest	(13,977)	(24,236)
Proceeds from sale of assets	17,294	0
Deposits on asset sales	(3,300)	0
Net cash used in investing activities	(599,725)	(603,823)
Cash flows from financing activities:
Proceeds from issuances on line of credit	0	368,100
Payments on borrowings under line of credit	0	(355,900)
Proceeds from issuance of 6.375% Senior notes due 2022	600,000	0
Repurchase of 8.25% Senior subordinated notes due 2016	(200,000)	0
Repurchase of 10.25% Senior notes due 2014	(149,999)	(91,044)
Long-term borrowings under credit facility	1,215,500	529,400
Repayments of long-term borrowings under credit facility	(1,237,000)	(214,400)
Financing obligation	(309)	(281)
Debt issuance costs	(11,424)	(1,176)
Dividends paid	(13,160)	(12,480)
Stock options and restricted stock issued	3,551	7,333
Excess income tax benefit	756	2,197
Net cash provided by financing activities	207,915	231,749
Net decrease in cash and cash equivalents	(194)	(184)
Cash and cash equivalents at beginning of period	298	278
Cash and cash equivalents at end of period	104	94
Noncash investing activities:
Accrued capital expenditures	61,044	19,162
Asset retirement obligation	$ 16,854	$ 6,477

Condensed Statement of Shareholders' Equity - 9 months ended Sep. 30, 2012 - USD ($) $ in Thousands	Total	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Class A Common Stock	Class B Common Stock
Balances at Dec. 31, 2011	$ 840,729	$ 350,158	$ 495,549	$ (5,517)	$ 521	$ 18
Increase (Decrease) in Shareholders' Equity
Stock options and restricted stock issued	3,551	3,548			3
Stock based compensation expense	7,589	7,589
Income tax effect of stock option exercises	756	756
Dividends ($0.24 per share)	(13,160)		(13,160)
Net earnings	133,040		133,040
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	3,781			3,781
Balances at Sep. 30, 2012	$ 976,286	$ 362,051	$ 615,429	$ (1,736)	$ 524	$ 18

- Definition

This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation".

+ References

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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

+ References + Details

Condensed Statement of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Statement of Stockholders' Equity [Abstract]
Dividends per share (in dollars per share)	$ 0.08	$ 0.08	$ 0.24	$ 0.23

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation These Condensed Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial reporting. Pursuant to the rules and regulations of the Securities and Exchange Commission (SEC), the unaudited Condensed Financial Statements do not include all disclosures required by GAAP. For a more complete understanding of Berry Petroleum Company's (the Company) operations, financial position and accounting policies, the unaudited Condensed Financial Statements and notes thereto should be read in conjunction with the Company's Annual Report on Form 10-K for the year ended December 31, 2011, previously filed with the SEC. All adjustments, consisting of normal and recurring accruals, which are, in the opinion of management, necessary to fairly state the Company's Condensed Financial Statements have been included herein. Interim results are not necessarily indicative of expected annual results because of the impact of fluctuations in prices received for oil and natural gas, as well as other factors. In the course of preparing the Condensed Financial Statements, management makes various assumptions, judgments and estimates to determine the reported amounts of assets, liabilities, revenues and expenses, and to prepare disclosures of commitments and contingencies. Changes in these assumptions, judgments and estimates will occur as a result of the passage of time and the occurrence of future events, and, accordingly, actual results could differ from amounts previously established. The Company's cash management process provides for the daily funding of checks as they are presented to the bank. Included in accounts payable at September 30, 2012 and December 31, 2011 were $23.7 million and $16.1 million, respectively, representing outstanding checks in excess of the bank balance (book overdraft). Recent Accounting Standards In December 2011, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2011-11 which requires that an entity disclose both gross and net information about instruments and transactions that are either eligible for offset in the balance sheet or subject to an agreement similar to a master netting agreement, including derivative instruments. ASU 2011-11 was issued in order to facilitate comparison between GAAP and IFRS financial statements by requiring enhanced disclosures, but does not change existing GAAP that permits balance sheet offsetting. This authoritative guidance is effective for annual reporting periods beginning on or after January 1, 2013, and interim periods within those annual periods. The Company is currently evaluating the provisions of ASU 2011-11 and assessing the impact, if any, it may have on the Company's financial position or results of operations.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

+ References

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-Name Accounting Research Bulletin (ARB)
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+ Details

Acquisitions and Divestitures	9 Months Ended
Acquisitions and Divestitures	Sep. 30, 2012
Business Combinations [Abstract]
Acquisitions and Divestitures	Acquisitions and Divestitures 2012 Acquisitions On September 12, 2012, the Company completed the acquisition of approximately 14,000 net acres contiguous to the Company's Brundage Canyon asset in the Uinta for an aggregate purchase price of $39.6 million, including usual and customary post-closing adjustments. Disclosures of purchase price allocation and also of pro forma revenues and net earnings for this acquisition are not material and have not been presented. On April 13, 2012, the Company completed the acquisition of approximately 2,000 net acres and one well in the Wolfberry trend in the Permian for an aggregate purchase price of $14.9 million including usual and customary post-closing adjustments. Disclosures of purchase price allocation and also of pro forma revenues and net earnings for the acquisition of this acquisition are not material and have not been presented. 2012 Divestiture On December 21, 2011, the Company entered into an agreement to sell its assets related to proved developed properties in Elko, Eureka and Nye Counties, Nevada, which closed on January 31, 2012, for total cash consideration of $15.6 million. The Company recorded a $1.6 million gain in conjunction with the sale. The gain was recorded in the Condensed Statements of Operations under the caption gain on sale of assets. 2011 Acquisition On May 25, 2011, the Company acquired interests in producing properties on approximately 6,000 net acres in the Wolfberry trend in the Permian for an aggregate purchase price of $128.4 million. The acquisition was financed using the Company's credit facility. Disclosures of pro forma revenues and net earnings for this acquisition are not material and have not been presented.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 88-16
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph F4
-Subparagraph e
-Appendix F

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 51, 52
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 67-73
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Debt

9 Months Ended

Sep. 30, 2012

Debt Disclosure [Abstract]

Debt

Issuance and Sale of 6.375% Senior Notes Due 2022

On March 9, 2012, the Company issued $600 million aggregate principal amount of its 6.375% Senior notes due 2022 (2022 Notes) for net proceeds of $589.5 million. Interest is payable in arrears semi-annually in March and September of each year, beginning September 2012. The 2022 Notes are senior unsecured obligations of the Company, which rank effectively junior to all of the Company's existing and any future secured debt, to the extent of the value of the collateral securing that debt, equally in right of payment with the Company's 10.25% Senior notes due 2014 (2014 Notes) and 6.75% Senior notes due 2020 (2020 Notes), and senior in right of payment to any of the Company's future subordinated debt.

On and after March 15, 2017, the Company may redeem all or, from time to time, a part of the 2022 Notes upon not less than 30 nor more than 60 days’ notice, at the following redemption prices (expressed as a percentage of principal amount of notes to be redeemed), plus accrued and unpaid interest, if any, to the applicable redemption date (subject to the right of holders of record on the relevant record date to receive interest due on the relevant interest payment date), if redeemed during the 12-month period beginning on March 15 of the years indicated below:



2017	103.188	%
2018	102.125	%
2019	101.063	%
2020 and thereafter	100.000	%

In addition, before March 15, 2015, the Company may, at its option, on any one or more occasions redeem up to 35% of the aggregate principal amount of the 2022 Notes with the net cash proceeds of certain equity offerings and if certain conditions are met as described in the indenture governing the 2022 Notes, at a redemption price of 106.375% of the principal amount thereof, plus accrued and unpaid interest, if any, to the redemption date. At any time prior to March 15, 2017, the Company may also redeem all or part of the 2022 Notes at a redemption price equal to 100% of the principal amount of the notes redeemed plus a “make-whole” premium described in the indenture, plus accrued and unpaid interest, if any, to the redemption date.

Tender Offer and Redemption of Notes

On April 3, 2012, pursuant to the terms of the Offer to Purchase dated March 6, 2012, the Company repurchased $150.0 million aggregate principal amount of its 2014 Notes for an aggregate purchase price of $181.5 million, including accrued and unpaid interest. A related loss of $30.9 million was recorded in the second quarter of 2012, consisting of $26.4 million for premiums paid over par and $4.5 million for write-offs of net discounts and debt issuance costs. The 2014 Notes were repurchased using net proceeds from the issuance of the Company's 2022 Notes. Following the closing of the tender offer on April 3, 2012, $205.3 million aggregate principal amount of 2014 Notes was outstanding.

On April 9, 2012, the Company redeemed all $200 million aggregate principal amount of its 8.25% Senior subordinated notes due 2016 (2016 Notes) for an aggregate purchase price of $215.5 million, including accrued and unpaid interest. A related loss of $10.6 million was recorded in the second quarter of 2012 consisting of $8.3 million for premiums paid over par and $2.3 million for write-offs of debt issuance costs. The 2016 Notes were redeemed using net proceeds from the issuance of the Company's 2022 Notes.

Senior Secured Revolving Credit Facility

On April 13, 2012, as part of the semi-annual borrowing base redetermination process, the Company entered into a fourth amendment to its credit facility. Among other things, the fourth amendment increased the borrowing base to $1.4 billion. Total lender commitments remained unchanged at $1.2 billion.

Borrowings under the credit facility bear interest at either (i) LIBOR plus a margin between 1.50% and 2.50% or (ii) the prime rate plus a margin between 0.50% and 1.50%, in each case, based on the amount utilized. The annual commitment fee on the unused portion of the credit facility ranges between 0.35% and 0.50% based on the amount utilized.

As of September 30, 2012, there were $510.0 million in outstanding borrowings under the credit facility and $23.2 million in outstanding letters of credit, leaving $666.8 million in borrowing capacity available under the credit facility. The maximum amount available under the credit facility is subject to semi-annual redeterminations of the borrowing base in April and October of each year, based on the value of the Company's proved oil and natural gas reserves, in accordance with the lenders' customary procedures and practices. The Company and the lenders each have the right to one additional redetermination each year. The semi-annual redetermination in October 2012 did not result in any changes to the borrowing base, lender commitments, or other terms of the credit facility.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References + Details

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective income tax rate for the three months ended September 30, 2012 and 2011 was 37.8% and 37.8%, respectively. The effective income tax rate for the nine months ended September 30, 2012 and 2011 was 37.9% and 37.6%, respectively. The Company's provision for income taxes differed from the U.S. statutory rate of 35% primarily due to state income taxes, domestic production activities deduction, percentage depletion, nondeductible employee compensation and other permanent differences. As of September 30, 2012, the Company had a gross liability for uncertain income tax benefits of $2.8 million, which, if recognized, would impact the effective income tax rate. There have been no significant changes to the calculation of uncertain income tax benefits during 2012. Consistent with the Company's policy, interest and penalties on income taxes have been recorded as a component of the income tax provision. The Company estimates that it is reasonably possible that the balance of unrecognized income tax benefits as of September 30, 2012 could decrease by a maximum of $2.6 million in the next 12 months due to the expiration of statutes of limitation and audit settlements.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 136, 172
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 43, 44, 45, 46, 47, 48, 49
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Earnings Per Share

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Earnings Per Share

Basic net earnings per share is calculated by dividing net earnings available to common shareholders by the weighted average shares outstanding-basic during each period. Diluted earnings per share is calculated by dividing earnings available to common shareholders by the weighted average shares outstanding-dilutive, which includes the effect of potentially dilutive securities. Potentially dilutive securities consist of unvested restricted stock awards and outstanding stock options. No potential shares of common stock are included in the computation of any diluted per share amount when a net loss exists.

The two-class method of computing net earnings per share is required for those entities that have participating securities. The two-class method is an earnings allocation formula that determines net earnings per share for participating securities according to dividends declared (or accumulated) and participation rights in undistributed earnings. Unvested restricted shares issued under the Company's equity incentive plans prior to January 1, 2010 have the right to receive non-forfeitable dividends, participating on an equal basis with common shares, and thus are classified as participating securities. Participating securities do not have a contractual obligation to share in the Company's losses. Therefore, in periods of net loss, no portion of the loss is allocated to participating securities. Unvested restricted shares issued subsequent to January 1, 2010 under the Company's equity incentive plans do not participate in dividends. Stock options issued under the Company's equity incentive plans do not participate in dividends.

The following table shows the computation of basic and diluted net earnings per share for the three and nine months ended September 30, 2012 and 2011:



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in thousands, except per share data)	2012		2011		2012		2011
Net earnings	$	18,126	$	134,001	$	133,040	$	186,670
Less: net earnings allocable to participating securities	118		1,207		709		1,797
Net earnings available for common shareholders	$	18,008	$	132,794	$	132,331	$	184,873

Basic net earnings per share	$	0.33	$	2.45	$	2.41	$	3.42
Diluted net earnings per share	$	0.33	$	2.42	$	2.39	$	3.38
Basic weighted average shares outstanding	54,945		54,211		54,883		54,029
Add: Dilutive effects of stock options and RSUs	336		654		395		743
Dilutive weighted average shares outstanding	55,281		54,865		55,278		54,772

Not included in the diluted earnings per share calculation were 0.7 million and 0.6 million stock options and RSUs, for the three and nine months ended September 30, 2012, respectively, because their effect would have been anti-dilutive. There were no stock options or RSUs excluded from the diluted earnings per share calculation for the three and nine months ended September 30, 2011.

Asset Retirement Obligation

9 Months Ended

Sep. 30, 2012

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligation

The following table summarizes the activity for the Company's asset retirement obligation (ARO) for the nine months ended September 30, 2012 and 2011:



	Nine Months Ended
	September 30,
(in thousands)	2012			2011
Beginning balance at January 1	$	64,019		$	53,443
Liabilities incurred	5,862			2,169
Liabilities settled	(2,763		)	(1,921		)
Liabilities assumed	2,651			119
Disposition of assets	(705		)	—
Accretion expense	4,201			3,593
Revisions in estimated cash flows	10,992			4,308
Ending balance at September 30	$	84,257		$	61,711

ARO reflects the estimated present value of the amount of dismantlement, removal, site reclamation and similar activities associated with the Company's oil and natural gas properties. Inherent in the fair value calculation of ARO are numerous assumptions and judgments including the ultimate settlement amounts, inflation factors, credit adjusted discount rates, timing of settlement and changes in the legal, regulatory, environmental and political environments. To the extent future revisions to these assumptions impact the fair value of the existing ARO liability, a corresponding adjustment is made to the oil and natural gas property balance.

Equity Incentive Compensation Plans

9 Months Ended

Sep. 30, 2012

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Equity Incentive Compensation Plans

Stock-based compensation is measured at the grant date based on the fair value of the awards. The fair value is recognized on a straight-line basis over the requisite service period (generally the vesting period).

Total compensation cost recognized in the Condensed Statements of Operations for the grants under the Company's equity incentive compensation plans was $2.0 million and $1.9 million during the three months ended September 30, 2012 and 2011, respectively, and $7.2 million and $7.0 million during the nine months ended September 30, 2012 and 2011, respectively.

Stock Options

The following table summarizes stock option activity for the nine months ended September 30, 2012:



	Number of Shares		Weighted Average Exercise Price		Aggregate Intrinsic Value (in thousands)(1)		Number of Shares Exercisable
Outstanding at January 1, 2012	1,520,689		$	30.32	$	17,798	1,434,020
Granted	82,262		53.02
Exercised	(200,509	)	17.71		6,859
Canceled/expired	—		—
Outstanding at September 30, 2012	1,402,442		$	33.45	$	11,900	1,254,583

__________________________________


(1)	The intrinsic value of a stock option is the amount by which the market value of the underlying stock at the end of the related period exceeds the exercise price of the option.

In March 2012, 82,262 stock options were granted under the 2010 Equity Incentive Plan to certain executive officers and other officers of the Company with exercise prices equal to the closing market price of the Company's common stock on the grant date. These stock options generally vest ratably over a four-year service period from the grant date and are exercisable immediately upon vesting through the tenth anniversary of the grant date.

The grant date fair value of each option granted was estimated using the Black-Scholes option pricing model. Expected volatility was calculated based on the historical volatility of the Company's common stock, and the risk-free interest rate was based on U.S. Treasury yield curve rates with maturities consistent with the expected life of each option. The key assumptions used in computing the weighted average fair market value of stock options granted were as follows:



	2012
Expected volatility	50.00	%
Risk-free interest rate	0.95	%
Dividend yield	0.57	%
Expected term (in years)	5.2

As of September 30, 2012, there were $2.7 million of total unrecognized compensation costs related to outstanding stock options. These costs are expected to be recognized over 3.5 years.

Restricted Stock Units

The following table summarizes restricted stock unit (RSU) activity for the nine months ended September 30, 2012:



	RSUs		Weighted Average Grant Date Fair Value		Vest Date Fair Value (in thousands)
Outstanding at January 1, 2012	915,022		$	23.88
Granted	162,612		50.71
Issued	(50,660	)	42.94		$	2,446
Canceled/expired	(14,956	)	40.53
Outstanding at September 30, 2012(1)(2)	1,012,018		$	27.12

__________________________________


(1)	The balance outstanding includes 43,554 RSUs granted to non-employee directors that are 100% vested at date of grant, but are subject to deferral elections delaying the date on which the corresponding shares are issued.


(2)	The balance outstanding includes 469,165 RSUs granted to executive officers and other officers that have vested in accordance with the RSU agreement, but are subject to deferral elections delaying the date on which the corresponding shares are issued.

As of September 30, 2012, there were $12.8 million of total unrecognized compensation costs related to RSUs granted. These costs are expected to be recognized over 3.5 years.

Performance Share Program

The following table summarizes performance share award activity for the nine months ended September 30, 2012:



	Performance Share Awards(1)	Weighted Average Grant Date Fair Value		Vest Date Fair Value (in thousands)
Outstanding at January 1, 2012	162,849	$	39.00
Granted	59,738	63.69
Issued	—	—		$	—
Canceled/expired	—	—
Outstanding at September 30, 2012	222,587	$	45.79

__________________________________


(1)	Reflects the maximum number of performance shares that can be issued.

In March 2012, 59,738 RSUs that are subject to performance metrics and a three-year service condition (performance shares) were granted to executive officers and certain other officers. The vesting of the performance shares is contingent upon satisfying certain performance criteria. No performance shares will vest unless, from January 1, 2012 to December 31, 2014, the Company maintains an interest coverage ratio of at least 2.5 to 1.0, achieves a defined total shareholder return as compared to the Company's defined peer group and achieves a defined level of compounded annual production growth as measured by average annual barrels of oil equivalent per day (excluding acquisitions and divestitures). If such thresholds are met, the number of performance shares that vest is based on the excess total shareholder return and compounded annual production growth over the thresholds.

For the portion of the performance shares subject to a performance-based vesting condition based on the Company's annual production growth, the grant date fair value was determined by reference to the closing price of the Company's common stock on the date of grant. The Company recognizes compensation expense when it becomes probable that these conditions will be achieved. However, any such compensation expense recognized is reversed if vesting does not actually occur.

For the portion of the performance shares subject to a market performance-based vesting condition based on the Company's total shareholder return, the grant date fair value was estimated using a Monte Carlo simulation method. The Monte Carlo model is based on random projections of stock price paths and must be repeated numerous times to achieve a probabilistic assessment. Expected volatility was calculated based on the historical volatility of the Company's common stock, and the risk-free interest rate is based on U.S. Treasury yield curve rates with maturities consistent with the three-year vesting period. The key assumptions used in valuing the market-based restricted shares were as follows:



	2012
Number of simulations	100,000
Expected volatility	50	%
Risk-free interest rate	0.42	%

All compensation expense related to the market performance-based awards will be recognized if the requisite service period is fulfilled, even if the market condition is not achieved.

As of September 30, 2012, there were $2.5 million of total unrecognized compensation costs related to performance shares granted. These costs are expected to be recognized over 2.3 years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 50
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6406099&loc=d3e25284-112666

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5444-113901

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph 64, 65, A240
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 93-6
-Paragraph 53
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Derivative Instruments

9 Months Ended

Sep. 30, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments

The Company uses financial derivative instruments as part of its price risk management program to achieve a more predictable, economic cash flow from its oil production by reducing its exposure to price fluctuations. The Company has historically entered into financial commodity swap and collar contracts to fix the floor and ceiling prices received for a portion of the Company's oil and natural gas production. During the second quarter of 2012, the Company began entering into derivative contracts to fix the floor and ceiling prices paid for a portion of its natural gas consumption. The terms of the Company's derivative contracts depend on various factors, including management's view of future crude oil and natural gas prices, acquisition economics on purchased assets and future financial commitments. The Company periodically enters into interest rate derivative agreements to protect against changes in interest rates on its floating rate debt. For further discussion related to the fair value of the Company's derivatives, see Note 9 to the Condensed Financial Statements.

As of September 30, 2012, the Company had commodity derivatives associated with the following volumes:



	2012	2013	2014	2015
Oil sales, Bbl/D:	21,000	16,800	7,500	3,000
Natural gas purchases, MMBtu/D:	—	10,000	—	—

The Company entered into the following derivative instruments during the nine months ended September 30, 2012:



Crude Oil Sales (NYMEX WTI) Three-Way Collars
Term	Average Barrels Per Day	Sold Put / Purchased Put / Sold Call
Full year 2013	800	$75.00 / $95.00 / $101.70
Full year 2013 and 2014	1,000	$70.00 / $90.00 / $100.00
Full year 2014	1,000	$70.00 / $90.00 / $120.00
Full year 2014	1,000	$70.00 / $90.00 / $121.80
Full year 2014	1,500	$70.00 / $90.00 / $100.00
Full year 2014 and 2015	1,000	$70.00 / $90.00 / $104.85
Full year 2015	2,000	$70.00 / $90.00 / $100.00



Natural Gas Purchases (NYMEX SoCal Border) Three-Way Collars
Term	Average MMBtus Per Day	Sold Put / Purchased Call / Sold Call
Full year 2013	1,000	$2.90 / $4.00 / $5.00
Full year 2013	1,000	$2.96 / $4.25 / $5.25
Full year 2013	1,000	$2.70 / $4.00 / $5.00
Full year 2013	2,000	$3.03 / $4.25 / $5.25



Natural Gas Purchases (NYMEX SoCal Border) Purchased Calls
Term	Average MMBtus Per Day	Strike Price	Deferred Premium per MMBtu
Full year 2013	1,000	$3.50	$0.43
Full year 2013	1,000	$3.50	$0.46
Full year 2013	1,000	$3.50	$0.4975
Full year 2013	2,000	$3.50	$0.5325

In March 2012, the Company terminated certain of its natural gas derivative instruments, which were associated with a total of 15,000 MMBtu/D for the remainder of 2012. The termination resulted in a net loss of $1.9 million, including cash settlements and non-cash fair value losses, and was recorded in the Condensed Statements of Operations under the caption realized and unrealized loss (gain) on derivatives, net.

Discontinuance of Cash Flow Hedge Accounting

Effective January 1, 2010, the Company elected to de-designate all of its commodity and interest rate derivative contracts that had been previously designated as cash flow hedges as of December 31, 2009. As a result, subsequent to December 31, 2009, the Company recognizes all gains and losses from changes in commodity derivative fair values immediately in earnings rather than deferring any such amounts in accumulated other comprehensive loss (AOCL). As a result of discontinuing hedge accounting, the changes in fair values of the Company's derivative contracts designated as cash flow hedges as of December 31, 2009 were frozen in AOCL and are reclassified into earnings as the original hedge transactions settle.

At December 31, 2011, AOCL consisted of $8.9 million ($5.5 million, net of income tax) of net unrealized losses on commodity and interest rate contracts that had been previously designated as cash flow hedges. At September 30, 2012, AOCL consisted of $2.8 million ($1.7 million net of income tax) of net unrealized losses on commodity and interest rate contracts that had been previously designated as cash flow hedges. During the three and nine months ended September 30, 2012, $2.4 million ($1.5 million, net of income tax) and $6.1 million ($3.8 million, net of income tax), respectively, of non-cash amortization of AOCL related to de-designated hedges was reclassified from AOCL into earnings. The Company expects to reclassify the remaining after-tax net losses of $1.7 million related to de-designated commodity and interest rate derivative contracts during the remainder of 2012.

The following tables detail the fair value of derivatives recorded on the Company's Condensed Balance Sheets, by category:



	September 30, 2012
	Derivative Assets			Derivative Liabilities
(in millions)	Balance Sheet Classification	Fair Value		Balance Sheet Classification	Fair Value
Current:
Commodity	Derivative assets	$	10.6	Derivative liabilities	$	1.3
Long term:
Commodity	Derivative assets	11.1		Derivative liabilities	1.4
Total derivatives		$	21.7		$	2.7



	December 31, 2011
	Derivative Assets			Derivative Liabilities
(in millions)	Balance Sheet Classification	Fair Value		Balance Sheet Classification	Fair Value
Current:
Commodity	Derivative assets	$	6.1	Derivative liabilities	$	20.4
Long term:
Commodity	Derivative assets	7.0		Derivative liabilities	15.5
Total derivatives		$	13.1		$	35.9

The table below summarizes the location and the amount of derivative instrument losses (gains) before income taxes reported in the Condensed Statements of Operations for the periods indicated:



		Three Months Ended						Nine Months Ended
(in millions)	Location of Loss (Gain) Recognized in Earnings	September 30,						September 30,
Description of Loss (Gain)	Location of Loss (Gain) Recognized in Earnings	2012			2011			2012			2011
Commodity
Loss reclassified from AOCL into earnings (amortization of frozen amounts)	Oil and natural gas sales	$	2.7		$	15.5		$	7.9		$	45.0
Loss (gain) recognized in earnings (cash settlements and mark-to-market movements)	Realized and unrealized loss (gain) on derivatives, net	28.3			(162.1		)	(56.3		)	(126.4		)
Interest rate
(Gain) loss reclassified from AOCL into earnings (amortization of frozen amounts)	Interest	$	(0.3	)	$	—		$	(1.8	)	$	1.2

Credit Risk

The Company does not require collateral or other security from counterparties to support derivative instruments. However, the agreements with those counterparties typically contain netting provisions such that if a default occurs, the non-defaulting party can offset the amount payable to the defaulting party under the derivative contract with the amount due from the defaulting party. As a result of the netting provisions, the Company's maximum amount of loss due to credit risk is limited to the net amounts due to and from the counterparties under the derivative contracts. The maximum amount of loss due to credit risk that the Company would have incurred if all counterparties to its derivative contracts failed to perform at September 30, 2012 was $19.8 million.

As of September 30, 2012, the counterparties to the Company's commodity derivative contracts consist of nine financial institutions. The Company's counterparties or their affiliates are also lenders under the Company's credit facility. As a result, the counterparties to the Company's derivative agreements share in the collateral supporting the Company's credit facility. The Company is not generally required to post additional collateral under derivative agreements.

Certain of the Company's derivative agreements contain cross default provisions that require acceleration of amounts due under such agreements if the Company were to default on its obligations under its material debt agreements. In addition, if the Company were to default on certain of its material debt agreements, including its derivative agreements, the Company would be in default under the credit facility. As of September 30, 2012, the Company was in a net liability position with three of the counterparties to the Company's derivative instruments. As of September 30, 2012, the Company's largest two counterparties accounted for 80% of the value of its total net derivative positions.

- Definition

The entire disclosure for the entity's entire derivative instruments and hedging activities. Describes an entity's risk management strategies, derivatives in hedging activities and non-hedging derivative instruments, the assets, obligations, liabilities, revenues and expenses arising therefrom, and the amounts of and methodologies and assumptions used in determining the amounts of such items.

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+ Details

Fair Value Measurement

9 Months Ended

Sep. 30, 2012

Fair Value Disclosures [Abstract]

Fair Value Measurements

The authoritative guidance for fair value measurements establishes a three-tier fair value hierarchy, which prioritizes the inputs used to measure fair value. These tiers include: Level 1, defined as unadjusted quoted prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs for use when little or no market data exists, therefore requiring an entity to develop its own assumptions.

A financial instrument's categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the classification of assets and liabilities within the fair value hierarchy. The Company recognizes transfers between levels at the end of the reporting period for which the transfer has occurred.

The fair value of all derivative instruments is estimated with industry-standard models that consider various assumptions, including quoted forward prices for commodities, time value, volatility factors and current market and contractual prices for the underlying instruments, as well as other relevant economic measures. The fair value of all derivative instruments is estimated using a combined income and market valuation methodology based upon forward commodity price and volatility curves. The curves are obtained from independent pricing services, and the Company has made no adjustments to the obtained prices. The independent pricing services publish observable market information from multiple brokers and exchanges. All valuations were compared against counterparty valuations to verify the reasonableness of prices. The Company also considers counterparty credit risk and its own credit risk in its determination of all estimated fair values. The Company has consistently applied these valuation techniques in all periods presented and believes it has obtained the most accurate information available for the types of derivative contracts it holds.

Assets (Liabilities) Measured at Fair Value on a Recurring Basis

The following table presents information about the Company's financial assets and liabilities measured at fair value on a recurring basis as of September 30, 2012 and December 31, 2011, and indicates the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair values:



(in millions)	Total			Level 1		Level 2			Level 3
Commodity derivative asset (liability), net
September 30, 2012	$	19.0		$	—	$	19.0		$	—
December 31, 2011	$	(22.7	)	$	—	$	(22.7	)	$	—

Changes in Level 3 Fair Value Measurements

The table below includes a rollforward of the Condensed Balance Sheet amounts (including the change in fair value) for financial instruments classified by the Company within Level 3 of the fair value hierarchy. When a determination is made to classify a financial instrument within Level 3, the determination is based upon the significance of the unobservable factors to the overall fair value measurement. Level 3 financial instruments typically include, in addition to the unobservable or Level 3 components, observable components (that is, components that are actively quoted and can be validated to external sources).



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in millions)	2012		2011		2012		2011
Fair value liability, beginning of period	$	—	$	—	$	—	$	(101.8	)
Transfers out of Level 3(1)	—		—		—		101.8
Realized and unrealized (gain) loss included in earnings	—		—		—		—
Settlements	—		—		—		—
Fair value liability, end of period	$	—	$	—	$	—	$	—
Total unrealized (gain) loss included in earnings related to financial assets and liabilities still on the Condensed Balance Sheets at September 30, 2012 and 2011	$	—	$	—	$	—	$	—

__________________________________


(1)	During the first quarter of 2011, the inputs used to value oil collars, natural gas collars and natural gas basis swaps were directly or indirectly observable, and these instruments were transferred to Level 2.

For further discussion related to the Company's derivatives, see Note 8 to the Condensed Financial Statements.

Fair Market Value of Financial Instruments

The Company uses various assumptions and methods in estimating the fair values of its financial instruments. The following table presents fair value information about the Company's financial instruments:



September 30, 2012	Carrying Amount		Estimated Fair Value
(in millions)			Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	—
Senior secured revolving credit facility(1)	510		—		510		—		510
10.25% Senior notes due 2014(2)	205		229		—		—		229
6.75% Senior notes due 2020	300		324		—		—		324
6.375% Senior notes due 2022	600		632		—		—		632
	$	1,615	$	1,185	$	510	$	—	$	1,695

__________________________________

(1)

The Company's credit facility can be repaid at any time without penalty. Interest is generally fixed for 30-day increments at the prime rate or LIBOR plus a stipulated margin for the amount utilized and at a stipulated percentage as a commitment fee for the portion not utilized. The carrying amount of the credit facility approximated fair value due to the short-term maturities of the borrowings and because the borrowings bear interest at variable market rates.


(2)	Carrying amount does not include unamortized discount of $2.7 million.



December 31, 2011
(in millions)	Carrying Amount		Estimated Fair Value
Senior secured revolving credit facility(1)	$	532	$	532
8.25% Senior subordinated notes due 2016	200		209
10.25% Senior notes due 2014(2)	355		402
6.75% Senior notes due 2020	300		302
	$	1,387	$	1,445

__________________________________

(1)


(2)	Carrying amount does not include unamortized discount of $6.6 million.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

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+ Details

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2012
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Uinta Crude Oil Sales Contract The Company is a party to a crude oil sales contract through June 30, 2013 with a refiner for the purchase of a minimum of 5,000 Bbl/D of its Uinta crude oil. Pricing under the contract, which includes transportation and gravity adjustments, is at a fixed percentage of WTI. Gross operated oil production from the Company's Uinta properties subject to the terms of this contract averaged approximately 4,035 Bbl/D in the first nine months of 2012. The Company anticipates the crude oil sales customer will be conducting maintenance on its refinery during the fourth quarter of 2012, resulting on a reduction of the volumes of the Company's Uinta crude oil purchased by such customer during periods of maintenance. Such volumes will either have to be stored or sold into alternative markets to be identified. Due to the possibility of refinery constraints in the Utah region, it is possible that the loss of the Company's crude oil sales customer in Utah could impact the marketability of a portion of the Company's Uinta crude oil volumes. See Item 1A. Risk Factors of the Company's Annual Report on Form 10-K for the year ended 2011 filed with the SEC on February 28, 2012. E. Texas Gathering System In July 2009, the Company closed on the financing of its E. Texas natural gas gathering system for $18.4 million in cash. The Company entered into concurrent long-term natural gas gathering agreements for the E. Texas production which contained an embedded lease. Accordingly, the $16.7 million net book value of the property is being depreciated over the remaining useful life of the asset and the cash received of $18.4 million was recorded as a financing obligation. A portion of the payments under the agreements is recorded as gathering expense and a portion as interest expense, with the balance being recorded as a reduction to the financing obligation. There are no minimum payments required under these agreements. For the three months ended September 30, 2012 and 2011, the Company incurred costs of $0.8 million and $1.2 million, respectively, under the agreements. For the nine months ended September 30, 2012 and 2011, the Company incurred costs of $2.5 million and $4.3 million, respectively, under the agreements. These amounts are recorded in the Condensed Financial Statements under the caption operating costs—oil and natural gas production. Carry and Earning Agreement On January 14, 2011, the Company entered into an amendment relating to certain contractual obligations to a third party co-owner of certain Piceance assets in Colorado. The amendment waives the $0.2 million penalty for each well not spud by February 2011 and requires the Company to reassign to such co-owner, by January 31, 2020, all of the interest acquired by the Company from the co-owner in each 160-acre tract in which the Company has not drilled and completed a well that is producing or capable of producing from a designated formation, or deeper formation, on January 1, 2020. The amendment also requires the Company to pay the first $9.0 million of costs incurred in connection with the construction of either an extension of the existing access road or a new access road, including the third party's 50% share. If by June 30, 2013 (which date may be extended in certain circumstances), the Company has not expended $9.0 million ($4.5 million of which would otherwise be such third party's responsibility) in road construction costs, then it will be obligated to pay the third party 50% of the difference between $12.0 million and the actual amount expended on road construction as of such date. Due to the need to obtain regulatory approvals, the Company has not yet commenced construction of either an extension of the existing access road or a new access road and may be unable to do so by June 30, 2013, thus triggering the payment obligation to the third party. Legal Matters Department of the Interior Notice of Proposed Debarment. On June 14, 2012, the Company received a Notice of Proposed Debarment issued by the United States Department of the Interior (DOI). Pursuant to the notice, the DOI's Office of the Inspector General is proposing to debar the Company from participation in certain federal contracts and assistance activities, including oil and natural gas leases, for a period of three years. The basis for the proposed debarment relates to the Company's purported noncompliance with Bureau of Land Management (BLM) regulations relating to the operation of certain equipment, and the submission of related site facility diagrams, in its Uinta operations. In 2011, the Company entered into a settlement agreement with the BLM and paid a $2.1 million civil penalty relating to the matter. The Company intends to contest the proposed debarment and believes the matter is without merit; nevertheless, the Company is currently engaged in discussions with the DOI to resolve the matter administratively. COGCC Order. On April 21, 2011, the Company received a proposed Order Finding Violation from the Colorado Oil and Gas Conservation Commission (COGCC) alleging that certain releases in late 2007 from a lined reserve pit located on a well pad in western Colorado violated COGCC regulations. Shortly thereafter, the Company entered into negotiations with the COGCC. While the Company denies that it violated any COGCC regulations in connection with the releases, on June 27, 2011, the COGCC approved and the Company later signed an Administrative Order on Consent under which the Company would pay $100,000, and fund a mutually acceptable public project in the amount of $73,000, in full satisfaction of the matter. The Company recorded these amounts in the second quarter of 2011, paid the $100,000 in July 2011 and paid the $73,000 to fund the public project in the third quarter of 2012, settling its obligation under the COGCC order. Royalty Payments. Certain of the Company's royalty payment calculations are being disputed. On August 1, 2012, a federal court entered a judgment against the Company that the Company had inappropriately taken certain post-wellhead deductions against royalty payments. The Company is in the process of negotiating a settlement of the judgment under which the Company's liability to the royalty owner will be approximately $3.9 million, inclusive of statutory interest, of which approximately $1.3 million had been previously recorded under the caption operating costs—oil and natural gas production. The Company recorded $1.9 million in operating costs—oil and natural gas production and $0.7 million in interest expense in the nine months ended September 30, 2012 in conjunction with the verdict. As of September 30, 2012, the Company may be required to pay amounts of up to approximately $3.9 million with respect to other royalty disputes. Other. The Company is involved in various other lawsuits, claims and inquiries, most of which are routine to the nature of its business. In the opinion of management, the resolution of these matters will not have a material effect on its financial position, results of operations or operating cash flows. Environmental Matters The Company has no material accrued environmental liabilities for its sites, including sites in which governmental agencies have designated the Company as a potentially responsible party, because it is not probable that a loss will be incurred and the minimum cost and/or amount of loss cannot be reasonably estimated. However, due to some of the uncertainties associated with environmental assessment and remediation activities, future expense to remediate the currently identified sites, and sites identified in the future, if any, could be incurred. Management believes, based upon current site assessments, that the ultimate resolution of any matters will not result in material costs incurred.

- Definition

The entire disclosure for commitments and contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6449706&loc=d3e16207-108621

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6398077&loc=d3e12565-110249

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25287-109308

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 14
-Paragraph 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9, 10, 11, 12
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Debt (Tables)

9 Months Ended

Sep. 30, 2012

Debt Disclosure [Abstract]

Senior notes, expressed as percentage of principal amount redeemed, plus accured and unpaid interest, by maturity



2017	103.188	%
2018	102.125	%
2019	101.063	%
2020 and thereafter	100.000	%

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Schedule of earnings per share, basic and diluted



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in thousands, except per share data)	2012		2011		2012		2011
Net earnings	$	18,126	$	134,001	$	133,040	$	186,670
Less: net earnings allocable to participating securities	118		1,207		709		1,797
Net earnings available for common shareholders	$	18,008	$	132,794	$	132,331	$	184,873

Basic net earnings per share	$	0.33	$	2.45	$	2.41	$	3.42
Diluted net earnings per share	$	0.33	$	2.42	$	2.39	$	3.38
Basic weighted average shares outstanding	54,945		54,211		54,883		54,029
Add: Dilutive effects of stock options and RSUs	336		654		395		743
Dilutive weighted average shares outstanding	55,281		54,865		55,278		54,772

Asset Retirement Obligation (Tables)

9 Months Ended

Sep. 30, 2012

Asset Retirement Obligation Disclosure [Abstract]

Summary of change in asset retirement obligation



	Nine Months Ended
	September 30,
(in thousands)	2012			2011
Beginning balance at January 1	$	64,019		$	53,443
Liabilities incurred	5,862			2,169
Liabilities settled	(2,763		)	(1,921		)
Liabilities assumed	2,651			119
Disposition of assets	(705		)	—
Accretion expense	4,201			3,593
Revisions in estimated cash flows	10,992			4,308
Ending balance at September 30	$	84,257		$	61,711

Equity Incentive Compensation Plans (Tables)

9 Months Ended

Sep. 30, 2012

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of stock options or units activity



	Number of Shares		Weighted Average Exercise Price		Aggregate Intrinsic Value (in thousands)(1)		Number of Shares Exercisable
Outstanding at January 1, 2012	1,520,689		$	30.32	$	17,798	1,434,020
Granted	82,262		53.02
Exercised	(200,509	)	17.71		6,859
Canceled/expired	—		—
Outstanding at September 30, 2012	1,402,442		$	33.45	$	11,900	1,254,583

__________________________________


(1)	The intrinsic value of a stock option is the amount by which the market value of the underlying stock at the end of the related period exceeds the exercise price of the option.

Summary of assumptions to estimate fair value of stock options



	2012
Expected volatility	50.00	%
Risk-free interest rate	0.95	%
Dividend yield	0.57	%
Expected term (in years)	5.2

Summary of restricted stock units activity



	RSUs		Weighted Average Grant Date Fair Value		Vest Date Fair Value (in thousands)
Outstanding at January 1, 2012	915,022		$	23.88
Granted	162,612		50.71
Issued	(50,660	)	42.94		$	2,446
Canceled/expired	(14,956	)	40.53
Outstanding at September 30, 2012(1)(2)	1,012,018		$	27.12

__________________________________


(1)	The balance outstanding includes 43,554 RSUs granted to non-employee directors that are 100% vested at date of grant, but are subject to deferral elections delaying the date on which the corresponding shares are issued.


(2)	The balance outstanding includes 469,165 RSUs granted to executive officers and other officers that have vested in accordance with the RSU agreement, but are subject to deferral elections delaying the date on which the corresponding shares are issued.

Summary of performance share awards activity



	Performance Share Awards(1)	Weighted Average Grant Date Fair Value		Vest Date Fair Value (in thousands)
Outstanding at January 1, 2012	162,849	$	39.00
Granted	59,738	63.69
Issued	—	—		$	—
Canceled/expired	—	—
Outstanding at September 30, 2012	222,587	$	45.79

Summary of assumptions used in valuing market-based restricted shares



	2012
Number of simulations	100,000
Expected volatility	50	%
Risk-free interest rate	0.42	%

Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of commodity derivatives



	2012	2013	2014	2015
Oil sales, Bbl/D:	21,000	16,800	7,500	3,000
Natural gas purchases, MMBtu/D:	—	10,000	—	—

Schedule of crude oil three way collars entered



Crude Oil Sales (NYMEX WTI) Three-Way Collars
Term	Average Barrels Per Day	Sold Put / Purchased Put / Sold Call
Full year 2013	800	$75.00 / $95.00 / $101.70
Full year 2013 and 2014	1,000	$70.00 / $90.00 / $100.00
Full year 2014	1,000	$70.00 / $90.00 / $120.00
Full year 2014	1,000	$70.00 / $90.00 / $121.80
Full year 2014	1,500	$70.00 / $90.00 / $100.00
Full year 2014 and 2015	1,000	$70.00 / $90.00 / $104.85
Full year 2015	2,000	$70.00 / $90.00 / $100.00

Schedule of natural gas purchases three-way collars entered



Natural Gas Purchases (NYMEX SoCal Border) Three-Way Collars
Term	Average MMBtus Per Day	Sold Put / Purchased Call / Sold Call
Full year 2013	1,000	$2.90 / $4.00 / $5.00
Full year 2013	1,000	$2.96 / $4.25 / $5.25
Full year 2013	1,000	$2.70 / $4.00 / $5.00
Full year 2013	2,000	$3.03 / $4.25 / $5.25

Schedule of natural gas purchases purchased calls



Natural Gas Purchases (NYMEX SoCal Border) Purchased Calls
Term	Average MMBtus Per Day	Strike Price	Deferred Premium per MMBtu
Full year 2013	1,000	$3.50	$0.43
Full year 2013	1,000	$3.50	$0.46
Full year 2013	1,000	$3.50	$0.4975
Full year 2013	2,000	$3.50	$0.5325

Schedule of derivative assets and liabilities



	September 30, 2012
	Derivative Assets			Derivative Liabilities
(in millions)	Balance Sheet Classification	Fair Value		Balance Sheet Classification	Fair Value
Current:
Commodity	Derivative assets	$	10.6	Derivative liabilities	$	1.3
Long term:
Commodity	Derivative assets	11.1		Derivative liabilities	1.4
Total derivatives		$	21.7		$	2.7



	December 31, 2011
	Derivative Assets			Derivative Liabilities
(in millions)	Balance Sheet Classification	Fair Value		Balance Sheet Classification	Fair Value
Current:
Commodity	Derivative assets	$	6.1	Derivative liabilities	$	20.4
Long term:
Commodity	Derivative assets	7.0		Derivative liabilities	15.5
Total derivatives		$	13.1		$	35.9

Summary of (gains) losses before income taxes of derivative instruments recognized in the condensed statements of income (loss)



		Three Months Ended						Nine Months Ended
(in millions)	Location of Loss (Gain) Recognized in Earnings	September 30,						September 30,
Description of Loss (Gain)	Location of Loss (Gain) Recognized in Earnings	2012			2011			2012			2011
Commodity
Loss reclassified from AOCL into earnings (amortization of frozen amounts)	Oil and natural gas sales	$	2.7		$	15.5		$	7.9		$	45.0
Loss (gain) recognized in earnings (cash settlements and mark-to-market movements)	Realized and unrealized loss (gain) on derivatives, net	28.3			(162.1		)	(56.3		)	(126.4		)
Interest rate
(Gain) loss reclassified from AOCL into earnings (amortization of frozen amounts)	Interest	$	(0.3	)	$	—		$	(1.8	)	$	1.2

- Definition

Tabular disclosure of the location and amount of gains and losses reported in the statement of financial performance, or when applicable, the statement of financial position. For example, (a) gains and losses recognized in the income statement on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges and (b) gains and losses initially recognized in other comprehensive income on derivative instruments designated and qualifying as cash flow hedges.

+ References + Details

Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value Disclosures [Abstract]

Assets (liabilities) measured at fair value on a recurring basis



(in millions)	Total			Level 1		Level 2			Level 3
Commodity derivative asset (liability), net
September 30, 2012	$	19.0		$	—	$	19.0		$	—
December 31, 2011	$	(22.7	)	$	—	$	(22.7	)	$	—

Changes in Level 3 fair value measurements



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in millions)	2012		2011		2012		2011
Fair value liability, beginning of period	$	—	$	—	$	—	$	(101.8	)
Transfers out of Level 3(1)	—		—		—		101.8
Realized and unrealized (gain) loss included in earnings	—		—		—		—
Settlements	—		—		—		—
Fair value liability, end of period	$	—	$	—	$	—	$	—
Total unrealized (gain) loss included in earnings related to financial assets and liabilities still on the Condensed Balance Sheets at September 30, 2012 and 2011	$	—	$	—	$	—	$	—

__________________________________


(1)	During the first quarter of 2011, the inputs used to value oil collars, natural gas collars and natural gas basis swaps were directly or indirectly observable, and these instruments were transferred to Level 2.

Schedule of fair values and carrying amounts of debt instruments



September 30, 2012	Carrying Amount		Estimated Fair Value
(in millions)			Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	—
Senior secured revolving credit facility(1)	510		—		510		—		510
10.25% Senior notes due 2014(2)	205		229		—		—		229
6.75% Senior notes due 2020	300		324		—		—		324
6.375% Senior notes due 2022	600		632		—		—		632
	$	1,615	$	1,185	$	510	$	—	$	1,695

__________________________________

(1)


(2)	Carrying amount does not include unamortized discount of $2.7 million.



December 31, 2011
(in millions)	Carrying Amount		Estimated Fair Value
Senior secured revolving credit facility(1)	$	532	$	532
8.25% Senior subordinated notes due 2016	200		209
10.25% Senior notes due 2014(2)	355		402
6.75% Senior notes due 2020	300		302
	$	1,387	$	1,445

__________________________________

(1)


(2)	Carrying amount does not include unamortized discount of $6.6 million.

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13467-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 19
-Subparagraph a, b, c(1), d(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 14
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15
-Subparagraph b-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph c(2), d, e, f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a, c(1), c(2), c(3), d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Tabular disclosure of the fair value measurement of liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs) by class of liability.

+ References + Details

Basis of Presentation (Details) - USD ($) $ in Millions	Sep. 30, 2012	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Outstanding checks in excess of the bank balance, included in accounts payable	$ 23.7	$ 16.1

Acquisitions and Divestitures (Details) $ in Thousands					9 Months Ended
Acquisitions and Divestitures (Details) $ in Thousands	Sep. 12, 2012 USD ($) a	Apr. 13, 2012 USD ($) a	Jan. 31, 2012 USD ($)	May 25, 2011 USD ($) a	Sep. 30, 2012 USD ($)	Sep. 30, 2011 USD ($)
Acquisitions
Purchase price paid, net of customary post-closing adjustments					$ 75,706	$ 155,443
Divestitures
Proceeds from sale of assets					$ 17,294	$ 0
Nevada Assets
Divestitures
Proceeds from sale of assets			$ 15,600
Gain on sale of assets			$ 1,600
Brundage Canyon Acquisition [Member]
Acquisitions
Interests acquired in oil and natural gas properties (in net acres) \| a	14,000
Purchase price paid, net of customary post-closing adjustments	$ 39,600
2012 [Member] \| Wolfberry Acquisition
Acquisitions
Interests acquired in oil and natural gas properties (in net acres) \| a		2,000
Purchase price paid, net of customary post-closing adjustments		$ 14,900
2011 [Member] \| Wolfberry Acquisition
Acquisitions
Interests acquired in oil and natural gas properties (in net acres) \| a				6,000
Purchase price paid, net of customary post-closing adjustments				$ 128,400

Debt (Issuance and Sale of 6.375% Senior Notes Due 2022) (Details) - USD ($) $ in Millions		9 Months Ended
	Mar. 09, 2012	Sep. 30, 2012
6.375% Senior notes due 2022
Debt Instrument
Interest rate on debt instrument (as a percent)	6.375%	6.375%
Aggregate principal amount of debt issued	$ 600.0
Net proceeds from issuance of long-term debt	$ 589.5
Redemption percentage, maximum (as a percent)		35.00%
10.25% Senior notes due 2014
Debt Instrument
Interest rate on debt instrument (as a percent)		10.25%
6.75% Senior notes due 2020
Debt Instrument
Interest rate on debt instrument (as a percent)		6.75%
March 9, 2012 through March 14, 2017 [Member] \| 6.375% Senior notes due 2022
Debt Instrument
Debt instrument redemption price percentage of principal amount plus make whole premium and accrued and unpaid interest (as a percent)		100.00%
March 9, 2012 through March 14, 2015 \| 6.375% Senior notes due 2022
Debt Instrument
Senior notes redemption price percentage of principal (as a percent)		106.375%
March 15, 2017 through March 14, 2018 \| 6.375% Senior notes due 2022
Debt Instrument
Senior notes redemption price percentage of principal (as a percent)		103.188%
March 15, 2018 through March 14, 2019 \| 6.375% Senior notes due 2022
Debt Instrument
Senior notes redemption price percentage of principal (as a percent)		102.125%
March 15, 2019 through March 14, 2020 \| 6.375% Senior notes due 2022
Debt Instrument
Senior notes redemption price percentage of principal (as a percent)		101.063%
March 15, 2020 and thereafter \| 6.375% Senior notes due 2022
Debt Instrument
Senior notes redemption price percentage of principal (as a percent)		100.00%
Minimum redemption notice at stipulated date and rate \| 6.375% Senior notes due 2022
Senior Notes, Expressed As Percentage Of Principal Amount Redeemed, Plus Accured and Unpaid Interest
Notice period range (in days)		30 days
Maximum redemption notice at stipulated date and rate \| 6.375% Senior notes due 2022
Senior Notes, Expressed As Percentage Of Principal Amount Redeemed, Plus Accured and Unpaid Interest
Notice period range (in days)		60 days

Debt (Tender Offer and Redemption of Notes) (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Apr. 09, 2012	Apr. 03, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Debt Instrument
Loss on extinguishment of debt			$ 0	$ (14,391)	$ (41,545)	$ (14,391)
10.25% Senior notes due 2014
Debt Instrument
Aggregate principal amount of tender offer		$ 150,000
Repayments of unsecured debt		181,500
Loss on extinguishment of debt		(30,900)
Remaining unsecured debt after redemption		205,300
8.25% Senior subordinated notes due 2016
Debt Instrument
Loss on extinguishment of debt	$ (10,600)
Extinguishment of debt, amount	200,000
Repayments of subordinated debt	215,500
Write off of deferred debt issuance cost	2,300
Premium Paid Over Par \| 10.25% Senior notes due 2014
Debt Instrument
Loss on extinguishment of debt		(26,400)
Premium Paid Over Par \| 8.25% Senior subordinated notes due 2016
Debt Instrument
Loss on extinguishment of debt	$ (8,300)
Write-off of Deferred Debt Issuance Cost and Net Discount \| 10.25% Senior notes due 2014
Debt Instrument
Loss on extinguishment of debt		$ (4,500)

Debt (Senior Secured Revolving Credit Facilty) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2012 USD ($) Redetermination	Dec. 31, 2011 USD ($)
Debt obligations
Outstanding borrowings under credit facility	$ 510,000	$ 531,500
Senior secured revolving credit facility
Debt obligations
Credit facility maximum borrowing base	1,400,000
Lender commitments	1,200,000
Letters of credit issued under the facility	23,200
Remaining borrowing capacity available under the credit facility	$ 666,800
Credit facility borrowing base number of additional yearly redeterminations (in redeterminations) \| Redetermination	1
Low End of the Range \| Senior secured revolving credit facility
Debt obligations
Line of credit facility, unused capacity, commitment fee (as a percent)	0.35%
Low End of the Range \| Senior secured revolving credit facility \| LIBOR
Debt obligations
Loans Payable Basis Spread On Variable Rate	1.50%
Low End of the Range \| Senior secured revolving credit facility \| Prime
Debt obligations
Loans Payable Basis Spread On Variable Rate	0.50%
High End of the Range \| Senior secured revolving credit facility
Debt obligations
Line of credit facility, unused capacity, commitment fee (as a percent)	0.50%
High End of the Range \| Senior secured revolving credit facility \| LIBOR
Debt obligations
Loans Payable Basis Spread On Variable Rate	2.50%
High End of the Range \| Senior secured revolving credit facility \| Prime
Debt obligations
Loans Payable Basis Spread On Variable Rate	1.50%

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Tax Disclosure [Abstract]
Effective tax rate (as a percent)	37.80%	37.80%	37.90%	37.60%
Federal statutory rate (as a percent)	35.00%	35.00%	35.00%	35.00%
Unrecognized tax benefit, if recognized, would affect the effective tax rate	$ 2.8		$ 2.8
Maximum reduction in unrecognized tax benefits due to expiration of statutes of limitation and audit settlements in next 12 months	$ 2.6		$ 2.6

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Abstract]
Net earnings	$ 18,126	$ 134,001	$ 133,040	$ 186,670
Less: earnings allocable to participating securities	118	1,207	709	1,797
Net earnings available for common shareholders	$ 18,008	$ 132,794	$ 132,331	$ 184,873
Basic net earnings per share (in dollars per share)	$ 0.33	$ 2.45	$ 2.41	$ 3.42
Diluted net earnings per share (in dollars per share)	$ 0.33	$ 2.42	$ 2.39	$ 3.38
Basic weighted average shares outstanding (in shares)	54,945,000	54,211,000	54,883,000	54,029,000
Add: Dilutive effects of stock options and RSUs (in shares)	336,000	654,000	395,000	743,000
Dilutive weighted average shares outstanding (in shares)	55,281,000	54,865,000	55,278,000	54,772,000
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	700,000	0	600,000	0

Asset Retirement Obligation (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Change in the asset retirement obligation
Beginning balance	$ 64,019	$ 53,443
Accretion expense	4,201	3,593
Revisions in estimated cash flows	10,992	4,308
Ending balance	84,257	61,711
Developmental Activities
Change in the asset retirement obligation
Liabilities incurred/assumed	5,862	2,169
Liabilities Settled
Change in the asset retirement obligation
Liabilities settled	(2,763)	(1,921)
Acquisition Activities
Change in the asset retirement obligation
Liabilities incurred/assumed	2,651	119
Divestitures Activities
Change in the asset retirement obligation
Liabilities settled	$ (705)	$ 0

Equity Incentive Compensation Plans (Equity Incentive Plans) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total compensation cost	$ 2.0	$ 1.9	$ 7.2	$ 7.0

- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References + Details

Equity Incentive Compensation Plans (Stock Options) (Details)
$ / shares in Units, $ in Thousands

9 Months Ended

Sep. 30, 2012

USD ($)

$ / shares

Sep. 30, 2012

USD ($)

$ / shares

Stock options activity

Outstanding at the beginning of the period (in shares)

1,520,689

Granted (in shares)

82,262

Exercised (in shares)

(200,509)

Canceled/expired (in shares)

Outstanding at the end of the period (in shares)

1,402,442

Stock options, weighted average exercise price

Outstanding at the beginning of the period (in dollars per share) | $ / shares

$ 30.32

Granted (in dollars per share) | $ / shares

53.02

Exercised (in dollars per share) | $ / shares

17.71

Canceled/expired (in dollars per share) | $ / shares

0.00

Outstanding at the end of the period (in dollars per share) | $ / shares

$ 33.45

Stock options, aggregate intrinsic value

Outstanding at the beginning of the period | $

$ 17,798

^[1]

Exercised | $

6,859

Outstanding at the end of the period | $

$ 11,900

Stock options, number of shares exercisable

Options outstanding at the beginning of the period (in shares)

1,434,020

Options outstanding at the end of the period (in shares)

1,254,583

Fair value assumptions

Expected volatility (as a percent)

50.00%

Risk-free interest rate (as a percent)

0.95%

Dividend yield (as a percent)

0.57%

Expected term (in years)

5 years 2 months

Total unrecognized compensation cost | $

$ 2,700

Vesting period (in years)

4 years

Anniversary date through which options are exercisable from grant date

Tenth Year

Period of recognition of unrecognized compensation cost (in years)

3 years 6 months

[1]	The intrinsic value of a stock option is the amount by which the market value of the underlying stock at the end of the related period exceeds the exercise price of the option.

Equity Incentive Compensation Plans (Restricted Stock Units and Performance Share Program) (Details)
$ / shares in Units, $ in Thousands

9 Months Ended

Sep. 30, 2012

USD ($)

$ / shares

Restricted Stock Units

Other than stock options activity

Outstanding at the beginning of the period (in shares) | shares

915,022

Granted (in shares) | shares

162,612

Issued (in shares) | shares

(50,660)

Canceled/expired (in shares) | shares

(14,956)

Outstanding at the end of the period (in shares) | shares

1,012,018

^[1],[2]

Weighted average grant date fair value

Outstanding at the beginning of the period (in dollars per share) | $ / shares

$ 23.88

Granted (in dollars per share) | $ / shares

50.71

Issued (in dollars per share) | $ / shares

42.94

Canceled/expired (in dollars per share) | $ / shares

40.53

Outstanding at the end of the period (in dollars per share) | $ / shares

$ 27.12

Vest date fair value - issued (in dollars) | $

$ 2,446

Performance-Based RSUs

Other than stock options activity

Outstanding at the beginning of the period (in shares) | shares

162,849

^[3]

Granted (in shares) | shares

59,738

Issued (in shares) | shares

Canceled/expired (in shares) | shares

Outstanding at the end of the period (in shares) | shares

222,587

^[3]

Weighted average grant date fair value

Outstanding at the beginning of the period (in dollars per share) | $ / shares

$ 39.00

Granted (in dollars per share) | $ / shares

63.69

Issued (in dollars per share) | $ / shares

0.00

Canceled/expired (in dollars per share) | $ / shares

0.00

Outstanding at the end of the period (in dollars per share) | $ / shares

$ 45.79

Vest date fair value - issued (in dollars) | $

$ 0

[1]	(1)The balance outstanding includes 43,554 RSUs granted to non-employee directors that are 100% vested at date of grant, but are subject to deferral elections delaying the date on which the corresponding shares are issued.
[2]	(2)The balance outstanding includes 469,165 RSUs granted to executive officers and other officers that have vested in accordance with the RSU agreement, but are subject to deferral elections delaying the date on which the corresponding shares are issued.
[3]	Reflects the maximum number of performance shares that can be issued.

Equity Incentive Compensation Plans (Restricted Stock Units and Performance Share Program) (Narrative) (Details) $ in Millions		9 Months Ended
	Sep. 30, 2012 USD ($) shares	Sep. 30, 2012 USD ($) ratio simulation shares
Equity Incentive Compensation Plans
Total unrecognized compensation cost \| $	$ 2.7	$ 2.7
Period of recognition of unrecognized compensation cost (in years)	3 years 6 months
Vesting period (in years)		4 years
Fair value assumptions used in market-based portion of performance shares valuation model (Monte Carlo model)
Expected volatility (as a percent)		50.00%
Risk-free interest rate (as a percent)		0.95%
Restricted Stock Units
Equity Incentive Compensation Plans
Total unrecognized compensation cost \| $	$ 12.8	$ 12.8
Period of recognition of unrecognized compensation cost (in years)	3 years 6 months
Granted (in shares)		162,612
Restricted Stock Units \| Executive officers and other officers
Equity Incentive Compensation Plans
Fully vested shares outstanding subject to deferral election by executive officers or other officers (in shares)	469,165	469,165
Restricted Stock Units \| Non-employee directors
Equity Incentive Compensation Plans
Fully vested shares outstanding subject to non-employee director deferral election (in shares)	43,554	43,554
Percentage of stock units vested at date of grant (as a percent)	100.00%	100.00%
Performance-Based RSUs
Equity Incentive Compensation Plans
Total unrecognized compensation cost \| $	$ 2.5	$ 2.5
Period of recognition of unrecognized compensation cost (in years)	2 years 3 months
Granted (in shares)		59,738
Number of years of service to be completed to participate in the program (in years)		3 years
Minimum interest coverage ratio, numerator \| ratio		2.5
Minimum interest coverage ratio, denominator \| ratio		1
Vesting period (in years)		3 years
Fair value assumptions used in market-based portion of performance shares valuation model (Monte Carlo model)
Number of simulations (in simulations) \| simulation		100,000
Expected volatility (as a percent)		50.00%
Risk-free interest rate (as a percent)		0.42%

Derivative Instruments (Details) $ in Thousands		3 Months Ended		9 Months Ended
Derivative Instruments (Details) $ in Thousands	Sep. 30, 2012 USD ($) bbl / day MMBtu / day OilBblD $ / MMBtu $ / Barrels	Sep. 30, 2012 USD ($) bbl / day MMBtu / day OilBblD $ / MMBtu $ / Barrels	Sep. 30, 2011 USD ($)	Sep. 30, 2012 USD ($) bbl / day MMBtu / day OilBblD $ / MMBtu $ / Barrels	Sep. 30, 2011 USD ($)	Dec. 31, 2011 USD ($)	Mar. 31, 2011 MMBtu / day
Accumulated Other Comprehensive Loss
Accumulated other comprehensive income (loss) before tax \| $	$ 2,800	$ 2,800		$ 2,800		$ 8,900
Accumulated other comprehensive loss \| $	1,736	1,736		1,736		$ 5,517
Reclassified unrealized losses, before tax from AOCL into earnings \| $		2,400		6,100
Reclassified unrealized losses, after tax from AOCL into earnings \| $		$ 1,505	$ 9,604	$ 3,781	$ 28,649
Net losses after-tax expected to be reclassified into earnings from AOCL during the remainder of 2012 \| $	$ (1,700)
Crude Oil Sales - Three-way collars - Derivative 1 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	1,000	1,000		1,000
Crude Oil Sales - Three-way collars - Derivative 2 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	1,000	1,000		1,000
Crude Oil Sales - Three-way collars - Derivative 3 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	800	800		800
Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	1,000	1,000		1,000
Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	1,000	1,000		1,000
Crude Oil Sales - Three-way collars - Derivative 5 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	1,500	1,500		1,500
Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	1,000	1,000		1,000
Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	1,000	1,000		1,000
Crude Oil Sales - Three-way collars - Derivative 7 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| bbl / day	2,000	2,000		2,000
Natural Gas Sales - Call Options - Derivative 1 \| Full 2013 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	1,000	1,000		1,000
Strike price \| $ / MMBtu	3.50	3.50		3.50
Deferred premium per MMBtu \| $ / MMBtu	0.43	0.43		0.43
Natural Gas Sales - Call Options - Derivative 2 \| Full 2013 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	1,000	1,000		1,000
Strike price \| $ / MMBtu	3.50	3.50		3.50
Deferred premium per MMBtu \| $ / MMBtu	0.46	0.46		0.46
Natural Gas Sales - Call Options - Derivative 3 \| Full 2013 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	1,000	1,000		1,000
Strike price \| $ / MMBtu	3.50	3.50		3.50
Deferred premium per MMBtu \| $ / MMBtu	0.4975	0.4975		0.4975
Natural Gas Sales - Call Options - Derivative 4 \| Full 2013 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	2,000	2,000		2,000
Strike price \| $ / MMBtu	3.50	3.50		3.50
Deferred premium per MMBtu \| $ / MMBtu	0.5325	0.5325		0.5325
Termination of Natural Gas Derivatives \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day							15,000
Termination of Natural Gas Derivatives
Net loss resulting from termination of natural gas derivatives \| $				$ (1,900)
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 1 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 2 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 3 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	75	75		75
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 5 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Sold Put \| Crude Oil Sales - Three-way collars - Derivative 7 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	70	70		70
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 1 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 2 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 3 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	95	95		95
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 5 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Purchased Put \| Crude Oil Sales - Three-way collars - Derivative 7 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Put (in dollars per barrel)	90	90		90
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 1 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	120	120		120
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 2 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	121.80	121.80		121.80
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 3 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	101.7	101.7		101.7
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	100	100		100
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 4 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	100	100		100
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 5 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	100	100		100
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	104.85	104.85		104.85
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 6 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	104.85	104.85		104.85
Sold Call \| Crude Oil Sales - Three-way collars - Derivative 7 [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Call (in dollars per barrel)	100	100		100
Natural Gas [Member] \| Full 2012 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	0	0		0
Natural Gas [Member] \| Full 2013 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	10,000	10,000		10,000
Natural Gas [Member] \| Full 2014 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	0	0		0
Natural Gas [Member] \| Full 2015 Term [Member] \| Natural Gas [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	0	0		0
Crude Oil [Member] \| Full 2012 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| OilBblD	21,000	21,000		21,000
Crude Oil [Member] \| Full 2013 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| OilBblD	16,800	16,800		16,800
Crude Oil [Member] \| Full 2014 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| OilBblD	7,500	7,500		7,500
Crude Oil [Member] \| Full 2015 Term [Member] \| Crude Oil [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| OilBblD	3,000	3,000		3,000

Derivative Instruments Derivative Instruments (Details 2) - Full 2013 Term [Member] - Natural Gas [Member]	Sep. 30, 2012 MMBtu / day $ / MMBtu
Natural Gas Sales - Three-way collars - Derivative 1 [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	1,000
Natural Gas Sales - Three-way collars - Derivative 2 [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	1,000
Natural Gas Sales - Three-way collars - Derivative 3 [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	1,000
Natural Gas Sales - Three-way collars - Derivative 4 [Member]
Derivative instruments
Notional amount of derivatives (Bbl/MMBtu per day) \| MMBtu / day	2,000
Sold Put \| Natural Gas Sales - Three-way collars - Derivative 1 [Member]
Derivative instruments
Put (in dollars per MMBtu)	2.9
Sold Put \| Natural Gas Sales - Three-way collars - Derivative 2 [Member]
Derivative instruments
Put (in dollars per MMBtu)	2.96
Sold Put \| Natural Gas Sales - Three-way collars - Derivative 3 [Member]
Derivative instruments
Put (in dollars per MMBtu)	2.70
Sold Put \| Natural Gas Sales - Three-way collars - Derivative 4 [Member]
Derivative instruments
Put (in dollars per MMBtu)	3.03
Purchased Call \| Natural Gas Sales - Three-way collars - Derivative 1 [Member]
Derivative instruments
Call (in dollars per MMBtu)	4
Purchased Call \| Natural Gas Sales - Three-way collars - Derivative 2 [Member]
Derivative instruments
Call (in dollars per MMBtu)	4.25
Purchased Call \| Natural Gas Sales - Three-way collars - Derivative 3 [Member]
Derivative instruments
Call (in dollars per MMBtu)	4
Purchased Call \| Natural Gas Sales - Three-way collars - Derivative 4 [Member]
Derivative instruments
Call (in dollars per MMBtu)	4.25
Sold Call \| Natural Gas Sales - Three-way collars - Derivative 1 [Member]
Derivative instruments
Call (in dollars per MMBtu)	5
Sold Call \| Natural Gas Sales - Three-way collars - Derivative 2 [Member]
Derivative instruments
Call (in dollars per MMBtu)	5.25
Sold Call \| Natural Gas Sales - Three-way collars - Derivative 3 [Member]
Derivative instruments
Call (in dollars per MMBtu)	5
Sold Call \| Natural Gas Sales - Three-way collars - Derivative 4 [Member]
Derivative instruments
Call (in dollars per MMBtu)	5.25

Derivative Instruments (Details 3) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Fair value derivative assets and liabilities classified in condensed balance sheets
Derivative assets, current	$ 10,573	$ 6,117
Derivative liabilities, current	1,309	20,365
Derivative assets, noncurrent	11,122	7,027
Derivative liabilities, noncurrent	1,358	15,505
Total derivative assets	21,700	13,100
Total derivative liabilities	2,700	35,900
Commodity contract
Fair value derivative assets and liabilities classified in condensed balance sheets
Derivative assets, current	10,572	6,117
Derivative liabilities, current	1,309	20,365
Derivative assets, noncurrent	11,122	7,027
Derivative liabilities, noncurrent	$ 1,358	$ 15,505

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References + Details

- Definition

Fair values as of the balance sheet date for all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments and which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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+ Details

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments which are expected to exist longer than one year or beyond the normal operating cycle, if longer, net of the effects of master netting arrangements.

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+ Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References + Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be extinguished or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

+ References

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+ Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be extinguished or otherwise disposed of after one year or beyond the normal operating cycle, if longer, net of the effects of master netting arrangements.

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+ Details

Derivative Instruments (Details 4) $ in Thousands		3 Months Ended		9 Months Ended
Derivative Instruments (Details 4) $ in Thousands	Sep. 30, 2012 USD ($) counterparty	Sep. 30, 2012 USD ($) counterparty	Sep. 30, 2011 USD ($)	Sep. 30, 2012 USD ($) counterparty	Sep. 30, 2011 USD ($)
Location and amount of derivative instrument (gains) losses before income taxes recognized in the condensed statements of operations
(Gain) loss reclassified from AOCL into earnings (amortization of frozen amount)		$ 2,400		$ 6,100
Loss (gain) recognized in earnings (cash settlements and mark-to-market movements)		$ 28,287	$ (162,145)	$ (56,314)	$ (126,437)
Credit risk
Maximum loss if all counterparties to derivative contracts failed to perform	$ 19,800
Number of counterparties to the Company's commodity derivative contracts (in counterparties) \| counterparty	9	9		9
Derivative number of counterparties with net liability position \| counterparty	3	3		3
Derivative instruments, number of largest counterparties (in counterparties) \| counterparty	2	2		2
Derivative value held by largest counterparties (as a percent)	80.00%	80.00%		80.00%
Oil and natural gas sales \| Commodity contract
Location and amount of derivative instrument (gains) losses before income taxes recognized in the condensed statements of operations
(Gain) loss reclassified from AOCL into earnings (amortization of frozen amount)		$ 2,700	15,500	$ 7,900	45,000
Realized and unrealized (gain) loss on derivatives, net \| Commodity contract
Location and amount of derivative instrument (gains) losses before income taxes recognized in the condensed statements of operations
Loss (gain) recognized in earnings (cash settlements and mark-to-market movements)		28,287	(162,145)	(56,314)	(126,437)
Interest \| Interest rate contract
Location and amount of derivative instrument (gains) losses before income taxes recognized in the condensed statements of operations
(Gain) loss reclassified from AOCL into earnings (amortization of frozen amount)		$ (300)	$ 0	$ (1,800)	$ 1,200

Fair Value Measurement (Details) - Assets (Liabilities) Measured at Fair Value on a Recurring Basis - Commodity contract - USD ($) $ in Millions	Sep. 30, 2012	Dec. 31, 2011
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis
Commodity derivative asset, net	$ 19.0
Commodity derivative liability, net		$ (22.7)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis
Commodity derivative asset, net	0.0
Commodity derivative liability, net		0.0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis
Commodity derivative asset, net	19.0
Commodity derivative liability, net		(22.7)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis
Commodity derivative asset, net	$ 0.0
Commodity derivative liability, net		$ 0.0

Fair Value Measurement (Details 2) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2012

Sep. 30, 2011

Sep. 30, 2012

Sep. 30, 2011

Changes in Level 3 fair value measurements

Fair value liability, beginning of period

$ 0.0

$ (101.8)

Transfers out of Level 3

^[1]

0.0

$ 0.0

0.0

101.8

Realized and unrealized (gain) loss included in earnings

0.0

Settlements

0.0

Fair value liability, end of period

0.0

Level 3

Changes in Level 3 fair value measurements

Total unrealized (gain) loss included in earnings related to financial assets and liabilities still on the Condensed Balance Sheets at June 30, 2012 and 2011

$ 0.0

[1]	During the first quarter of 2011, the inputs used to value oil collars, natural gas collars and natural gas basis swaps were directly or indirectly observable, and these instruments were transferred to Level 2.

Fair Value Measurement (Details 3) - USD ($)
$ in Thousands

9 Months Ended

Sep. 30, 2012

Sep. 30, 2011

Mar. 09, 2012

Dec. 31, 2011

Senior secured revolving credit facility

Fair value and carrying value of financial instruments

Interest Rate Generally Fixed (Number of Days)

30 days

8.25% Senior subordinated notes due 2016

Fair value and carrying value of financial instruments

Interest rate on debt instrument (as a percent)

8.25%

10.25% Senior notes due 2014, net of unamortized discount

Fair value and carrying value of financial instruments

Interest rate on debt instrument (as a percent)

10.25%

Unamortized discount

$ 2,715

$ 6,564

6.75% Senior notes due 2020

Fair value and carrying value of financial instruments

Interest rate on debt instrument (as a percent)

6.75%

6.375% Senior notes due 2022

Fair value and carrying value of financial instruments

Interest rate on debt instrument (as a percent)

6.375%

Level 1

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

$ 1,185,000

Level 2

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

510,000

Carrying Amount

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

1,615,000

1,387,000

Carrying Amount | Senior secured revolving credit facility

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

510,000

^[1]

532,000

^[2]

Carrying Amount | 8.25% Senior subordinated notes due 2016

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

200,000

Carrying Amount | 10.25% Senior notes due 2014, net of unamortized discount

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

205,000

^[3]

355,000

^[4]

Carrying Amount | 6.75% Senior notes due 2020

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

300,000

Carrying Amount | 6.375% Senior notes due 2022

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

600,000

Carrying Amount | Cash and cash equivalents

Fair value and carrying value of financial instruments

Cash and Cash Equivalents, Fair Value Disclosure

Estimated Fair Value

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

1,695,000

1,445,000

Estimated Fair Value | Senior secured revolving credit facility

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

510,000

^[1]

532,000

^[2]

Estimated Fair Value | 8.25% Senior subordinated notes due 2016

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

209,000

Estimated Fair Value | 10.25% Senior notes due 2014, net of unamortized discount

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

229,000

^[3]

402,000

^[4]

Estimated Fair Value | 6.75% Senior notes due 2020

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

324,000

$ 302,000

Estimated Fair Value | 6.375% Senior notes due 2022

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

632,000

Estimated Fair Value | Cash and cash equivalents

Fair value and carrying value of financial instruments

Cash and Cash Equivalents, Fair Value Disclosure

Estimated Fair Value | Level 1 | 10.25% Senior notes due 2014, net of unamortized discount

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

^[3]

229,000

Estimated Fair Value | Level 1 | 6.75% Senior notes due 2020

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

324,000

Estimated Fair Value | Level 1 | 6.375% Senior notes due 2022

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

632,000

Estimated Fair Value | Level 1 | Cash and cash equivalents

Fair value and carrying value of financial instruments

Cash and Cash Equivalents, Fair Value Disclosure

Estimated Fair Value | Level 2 | Senior secured revolving credit facility

Fair value and carrying value of financial instruments

Debt Instrument, Fair Value Disclosure

$ 510,000

[1]	The Company's credit facility can be repaid at any time without penalty. Interest is generally fixed for 30-day increments at the prime rate or LIBOR plus a stipulated margin for the amount utilized and at a stipulated percentage as a commitment fee for the portion not utilized. The carrying amount of the credit facility approximated fair value due to the short-term maturities of the borrowings and because the borrowings bear interest at variable market rates.
[2]	The Company's credit facility can be repaid at any time without penalty. Interest is generally fixed for 30-day increments at the prime rate or LIBOR plus a stipulated margin for the amount utilized and at a stipulated percentage as a commitment fee for the portion not utilized. The carrying amount of the credit facility approximated fair value due to the short-term maturities of the borrowings and because the borrowings bear interest at variable market rates.
[3]	Carrying amount does not include unamortized discount of $2.7 million.
[4]	Carrying amount does not include unamortized discount of $6.6 million.

Commitments and Contingencies (Details) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
Commitments and Contingencies (Details) $ in Millions	Jul. 31, 2009 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2011 USD ($)	Sep. 30, 2012 USD ($) bbl / day	Sep. 30, 2011 USD ($)
East Texas [Member]
E. Texas Gathering System
Proceeds from gas gathering system, financing obligation	$ 18.4
Net book value of property	$ 16.7
E. Texas gathering agreements, total cost incurred		$ 0.8	$ 1.2	$ 2.5	$ 4.3
Gross [Member] \| Uinta
Uinta Crude Oil Sales Contract
Sales contract, minimum purchase of crude oil (in Bbl/D) \| bbl / day				5,000
Gross oil production average (in Bbl/D) \| bbl / day				4,035

Commitments and Contingencies (Details 2)	1 Months Ended	3 Months Ended	12 Months Ended
Commitments and Contingencies (Details 2)	Jul. 31, 2011 USD ($)	Sep. 30, 2012 USD ($)	Dec. 31, 2011 USD ($)	Jan. 14, 2011 USD ($) a
Carry and Earning Agreement
Commitments
Amount of penalty waived for each well not spud				$ 200,000
Number of acres within each tract party to the earning and carrying agreement (in acres) \| a				160
Cumulative contingent construction expenditure				$ 9,000,000
Third party share of construction costs (as a percent)				50.00%
Construction expenditure otherwise payable by third party				$ 4,500,000
Penalty payable as a percentage of difference between specified amount and actual expended (as a percent)				50.00%
Specified amount for penalty calculation				$ 12,000,000
Bureau of Land Management
Commitments
Litigation Settlement, Expense			$ 2,100,000
Royalty payment disputes
Commitments
Estimated Litigation Liability		$ 3,900,000
Disputed royalty amounts the company may be required to pay		3,900,000
Cash Settlement \| Order of Violation from Colorado Oil and Gas Conservative Commission
Commitments
Payments for Legal Settlements	$ 100,000
Litigation Settlement, Expense			100,000
Mutually Acceptable Project \| Order of Violation from Colorado Oil and Gas Conservative Commission
Commitments
Payments for Legal Settlements		73,000
Litigation Settlement, Expense			$ 73,000
Recorded in Operating Expense in 2011 \| Royalty payment disputes
Commitments
Estimated Litigation Liability		1,300,000
Recorded in Operating Expense in 2012 \| Royalty payment disputes
Commitments
Estimated Litigation Liability		1,900,000
Recorded in Interest Expense in 2012 \| Royalty payment disputes
Commitments
Estimated Litigation Liability		$ 700,000