Unaudited Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities
Net income	$ 631,395	$ 518,874
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, amortization and accretion	694,729	500,359
Property impairments	161,960	93,153
Change in fair value of derivatives	37,638	(192,752)
Stock-based compensation	29,460	20,804
Provision for deferred income taxes	360,599	323,543
Dry hole costs	9,180	319
Gain on sale of assets, net	(112)	(67,139)
Other, net	4,308	3,604
Changes in assets and liabilities:
Accounts receivable	(178,171)	(112,316)
Inventories	(8,529)	(6,285)
Prepaid expenses and other	(11,118)	(5,080)
Accounts payable trade	151,266	(26,918)
Revenues and royalties payable	46,611	49,499
Accrued liabilities and other	41,791	48,240
Other noncurrent assets and liabilities	7,446	(8)
Net cash provided by operating activities	1,978,453	1,147,897
Cash flows from investing activities
Exploration and development	(2,767,448)	(2,584,434)
Purchase of producing crude oil and natural gas properties	(12,404)	(62,519)
Purchase of other property and equipment	(41,942)	(45,472)
Proceeds from sale of assets and other	22,406	101,298
Net cash used in investing activities	(2,799,388)	(2,591,127)
Cash flows from financing activities
Revolving credit facility borrowings	470,000	1,524,000
Repayment of revolving credit facility	(1,065,000)	(1,882,000)
Proceeds from issuance of Senior Notes	1,479,375	1,999,000
Proceeds from other debt	0	22,000
Repayment of other debt	(1,457)	(1,101)
Debt issuance costs	(2,263)	(7,117)
Repurchase of equity grants	(3,942)	(5,711)
Exercise of stock options	0	60
Net cash provided by financing activities	876,713	1,649,131
Net change in cash and cash equivalents	55,778	205,901
Cash and cash equivalents at beginning of period	35,729	53,544
Cash and cash equivalents at end of period	$ 91,507	$ 259,445