Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
OPERATING ACTIVITIES:
Net income	$ 184,746	$ 23,176	$ 195,867
Adjustments to reconcile net income (loss) to net cash provided (used) by operating activities:
Depreciation, depletion, amortization, and impairment	333,907	319,021	280,451
Impairment of oil and natural gas properties (Note 2)	0	283,606	0
(Gain) loss on derivatives	5,449	53,096	(159)
Derivatives settled	1,161	(51,853)	(2,254)
(Gain) loss on disposition of assets	(17,076)	(253)	595
Deferred tax expense	100,732	15,530	125,551
Employee stock compensation plans	21,317	16,956	14,303
Bad debt expense	0	90	260
ARO liability accretion	5,450	4,615	3,838
Other, net	2,250	781	294
Changes in operating assets and liabilities increasing (decreasing) cash:
Accounts receivable	2,967	13,994	(38,731)
Materials and supplies	(2,435)	(361)	(1,886)
Prepaid expenses and other	1,813	(3,466)	22,672
Accounts payable	15,715	10,187	(1,064)
Accrued liabilities	17,198	6,911	9,245
Contract advances	1,137	(1,119)	(527)
Net cash provided by operating activities	674,331	690,911	608,455
INVESTING ACTIVITIES:
Capital expeditures	(703,984)	(762,381)	(728,551)
Producing property and other acquisitions	0	(598,485)	(50,013)
Proceeds from disposition of property and equipment	120,910	281,824	10,328
Other	3,894	0	0
Net cash used in investing activities	(579,180)	(1,079,042)	(768,236)
FINANCING ACTIVITIES:
Borrowings under line of credit	222,500	735,300	441,500
Payments under line of credit	(293,600)	(714,200)	(554,500)
Proceeds from issuance of senior subordinated notes, net of debt issuance costs and discount	0	386,274	243,950
Proceeds from exercise of stock options	574	215	679
Tax benefit from stock options	8	121	1,174
Increase (decrease) in book overdrafts (Note 2)	(7,014)	(19,440)	26,454
Net cash provided by (used in) financing activities	(77,532)	388,270	159,257
Net increase (decrease) in cash and cash equivalents	17,619	139	(524)
Cash and cash equivalents, beginning of year	974	835	1,359
Cash and cash equivalents, end of year	18,593	974	835
Supplemental disclosure of cash flow information:
Interest paid (net of capitalization)	12,485	14,880	3,470
Income taxes	9,100	5,116	655
Changes in accounts payable and accrued liabilites related to purchases of property, plant, and equipment	(6,550)	(4,753)	(28,036)
Non-cash additions to oil and natural gas properties related to asset retirement obligations	$ (17,952)	$ 45,097	$ 23,345