Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
OPERATING ACTIVITIES:
Net income	$ 56,945	$ 40,206
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization	88,432	77,156
Loss on derivatives	18,366	2,093
Cash (payments) receipts on derivatives settled	(8,872)	4,871
Deferred tax expense	26,156	22,652
(Gain) loss on disposition of assets	(9,426)	84
Employee stock compensation plans	5,444	4,651
Other, net	1,179	1,601
Changes in operating assets and liabilities increasing (decreasing) cash:
Accounts receivable	(55,175)	(7,695)
Accounts payable	(11,430)	23,332
Material and supplies	2,781	(640)
Accrued liabilities	8,666	8,937
Other, net	394	2,412
Net cash provided by operating activities	123,460	179,660
INVESTING ACTIVITIES:
Capital expenditures	(197,266)	(192,927)
Proceeds from disposition of assets	36,748	1,456
Net cash used in investing activities	(160,518)	(191,471)
FINANCING ACTIVITIES:
Borrowings under credit agreement	4,000	123,300
Payments under credit agreement	(4,000)	(124,400)
Proceeds from exercise of stock options	850	72
Book overdrafts	18,667	13,018
Net cash provided by financing activities	19,517	11,990
Net increase (decrease) in cash and cash equivalents	(17,541)	179
Cash and cash equivalents, beginning of period	18,593	974
Cash and cash equivalents, end of period	1,052	1,153
Supplemental disclosure of cash flow information
Changes in accounts payable and accrued liabilities related to purchases of property, plant, and equipment	309	43,332
Non-cash reductions to oil and natural gas properties related to asset retirement obligations	(14,972)	(12,088)
Cash paid for income taxes	$ 7,100	$ 15