CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Statement of Cash Flows [Abstract]
Net income (loss)	$ (107,452)	$ 334,325
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net gain on divestiture activity	(38,497)	(52)
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	680,984	548,255
Exploratory dry hole expense	22,860	22,844
Impairment of proved properties	124,430	0
Abandonment and impairment of unproved properties	24,046	18,487
Stock-based compensation expense	20,492	24,568
Change in Net Profits Plan liability	(13,174)	(15,280)
Derivative (gain) loss	(285,491)	33,470
Derivative cash settlements	397,307	(62,894)
Amortization of deferred financing costs	5,803	4,433
Non-cash loss on extinguishment of debt	4,123	0
Deferred income taxes	(80,388)	198,180
Plugging and abandonment	(5,540)	(6,193)
Other, net	3,670	(2,934)
Changes in current assets and liabilities:
Accounts receivable	105,336	6,476
Prepaid expenses and other	587	234
Accounts payable and accrued expenses	(74,247)	(28,797)
Net cash provided by operating activities	784,849	1,075,122
Cash flows from investing activities:
Net proceeds from the sale of oil and gas properties	335,103	41,868
Capital expenditures	(1,261,871)	(1,317,862)
Acquisition of proved and unproved oil and gas properties	(7,088)	(459,277)
Other, net	(990)	(714)
Net cash used in investing activities	(934,846)	(1,735,985)
Cash flows from financing activities:
Proceeds from credit facility	1,604,500	536,500
Repayment of credit facility	(1,586,500)	(146,500)
Net proceeds from Senior Notes	490,951	0
Repayment of Senior Notes	(350,000)	0
Proceeds from sale of common stock	3,157	2,898
Dividends paid	(3,373)	(3,353)
Net share settlement from issuance of stock awards	(8,502)	(10,576)
Other, net	(159)	(85)
Net cash provided by financing activities	150,074	378,884
Net change in cash and cash equivalents	77	(281,979)
Cash and cash equivalents at beginning of period	120	282,248
Cash and cash equivalents at end of period	197	269
Supplemental schedule of additional cash flow information and noncash investing and financing activities:
Cash paid for interest, net of capitalized interest	88,920	79,119
Net cash paid for income taxes	$ 492	$ 1,979