CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013
Statement of Cash Flows [Abstract]
Net income	$ 334,325		$ 163,939
Adjustments to reconcile net income to net cash provided by operating activities:
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	548,255		620,232
Exploratory dry hole expense	22,844		5,878
Impairment of proved properties	0		61,706
Abandonment and impairment of unproved properties	18,487		8,459
Stock-based compensation expense	24,568		25,495
Change in Net Profits Plan liability	(15,280)		(6,423)
Derivative (gain) loss	33,470	[1]	(14,685)	[1]
Derivative cash settlement (gain) loss	(62,894)	[2]	12,715	[2]
Amortization of deferred financing costs	4,433		3,914
Deferred income taxes	198,180		98,619
Plugging and abandonment	(6,193)		(7,453)
Other, net	(2,986)		3,439
Changes in current assets and liabilities:
Accounts receivable	6,476		(45,209)
Prepaid expenses and other	234		(2,461)
Accounts payable and accrued expenses	(28,797)		72,704
Net Cash Provided by Operating Activities	1,075,122		1,000,869
Cash flows from investing activities:
Net proceeds from sale of oil and gas properties	41,868		20,498
Capital expenditures	(1,317,862)		(1,121,355)
Acquisition of proved and unproved oil and gas properties	(459,277)		(62,007)
Other, net	(714)		(3,509)
Net cash used in investing activities	(1,735,985)		(1,166,373)
Cash flows from financing activities:
Proceeds from credit facility	536,500		976,500
Repayment of credit facility	(146,500)		(1,288,500)
Deferred financing costs related to credit facility	0		(3,444)
Net proceeds from 2024 Notes	0		490,274
Proceeds from sale of common stock	2,898		4,450
Dividends paid	(3,353)		(3,314)
Net share settlement from issuance of stock awards	(10,576)		(16,203)
Other, net	(85)		(9)
Net cash provided by financing activities	378,884		159,754
Net change in cash and cash equivalents	(281,979)		(5,750)
Cash and cash equivalents at beginning of period	282,248		5,926
Cash and cash equivalents at ending of period	269		176
Supplemental schedule of additional cash flow information and noncash investing and financing activities:
Cash paid for interest, net of capitalized interest	79,119		59,841
Net cash paid (refunded) for income taxes	$ 1,979		$ (259)

[1] (2) Total derivative (gain) loss is reported in the derivative (gain) loss line item on the condensed consolidated statements of cash flows within net cash provided by operating activities.

[2] (1) Total derivative cash settlement (gain) loss is reported in the derivative cash settlement gain (loss) line item on the condensed consolidated statements of cash flows within net cash provided by operating activities.