Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 287,097	$ 219,492
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	368,920	283,669
Asset retirement obligation	6,868	5,283
Deferred income taxes	169,503	129,792
Stock compensation	7,272	7,112
(Gain) loss on derivative instruments	18,189	(12,057)
Settlements on derivative instruments	(5,804)	1,765
Changes in non-current assets and liabilities	(2,436)	5,790
Other, net	2,395	(2,116)
Changes in operating assets and liabilities:
Receivables, net	(81,702)	(55,060)
Other current assets	(19,182)	14,840
Accounts payable and accrued liabilities	18,649	(28,724)
Net cash provided by operating activities	769,769	569,786
Cash flows from investing activities:
Oil and gas expenditures	(1,138,539)	(776,138)
Sales of oil and gas assets	1,123	14,407
Sales of other assets	251	31,157
Other expenditures	(51,401)	(25,475)
Net cash used by investing activities	(1,188,566)	(756,049)
Cash flows from financing activities:
Net bank debt borrowings	(174,000)	142,000
Proceeds from other long-term debt	750,000
Financing costs incurred	(11,218)
Dividends paid	(26,022)	(22,448)
Issuance of common stock and other	4,061	1,705
Net cash provided by financing activities	542,821	121,257
Net change in cash and cash equivalents	124,024	(65,006)
Cash and cash equivalents at beginning of period	4,531	69,538
Cash and cash equivalents at end of period	$ 128,555	$ 4,532