CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (2,408,948)	$ 507,204	$ 564,689
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Impairments and other valuation losses	3,716,883
Depreciation, depletion and amortization	778,923	806,021	615,874
Asset retirement obligation	9,121	10,082	7,989
Deferred income taxes	(1,388,146)	298,293	329,700
Stock compensation	19,559	15,001	14,279
(Gain) loss on derivative instruments	(11,246)	(3,762)	209
Settlements on derivative instruments		7,641	(4,088)
Changes in non-current assets and liabilities	23,230	(2,440)	(141,215)
Other, net	4,206	(3,828)	751
Changes in operating assets and liabilities:
Receivables, net	186,699	(35,133)	(64,780)
Other current assets	37,954	(25,428)	14,234
Accounts payable and other current liabilities	(276,735)	45,714	(13,294)
Net cash provided by operating activities	691,500	1,619,365	1,324,348
Cash flows from investing activities:
Oil and gas expenditures	(979,044)	(2,108,250)	(1,572,288)
Sales of oil and gas assets	39,853	449,981	61,503
Sales of other assets	1,178	8,413	31,661
Other capital expenditures	(70,592)	(90,611)	(51,913)
Net cash used by investing activities	(1,008,605)	(1,740,467)	(1,531,037)
Cash flows from financing activities:
Net bank debt borrowings		(174,000)	174,000
Proceeds from other long-term debt		750,000
Proceeds from sale of common stock	752,100
Financing and underwriting fees	(24,633)	(11,616)	(100)
Dividends paid	(58,281)	(53,849)	(46,712)
Proceeds from exercise of stock options and other	21,439	11,898	14,494
Net cash provided by financing activities	690,625	522,433	141,682
Net change in cash and cash equivalents	373,520	401,331	(65,007)
Cash and cash equivalents at beginning of period	405,862	4,531	69,538
Cash and cash equivalents at end of period	$ 779,382	$ 405,862	$ 4,531