CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Cash flows from operating activities:
Net income (loss)	$ 666,051		$ 170,935		$ (54,249)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Gain (Loss) on Disposition of Oil and Gas Property	646		27,974		(27,018)
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	767,532		822,872		727,877
Exploratory dry hole expense	44,427		5,846		20,861
Impairment of proved properties	84,480		172,641		208,923
Abandonment and impairment of unproved properties	75,638		46,105		16,342
Share-based Compensation	32,694		32,347		30,185
Change in Net Profits Plan liability	(29,849)		(21,842)		(28,904)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	583,264	[1]	3,080	[1]	55,630	[1]
Derivative cash settlements	(28,419)		22,062		44,264
Amortization of debt discount and deferred financing costs	6,146		5,390		6,769
Deferred income taxes	397,780		105,555		(29,638)
Plugging and abandonment	(8,796)		(9,946)		(2,856)
Other	1,069		2,775		527
Changes in current assets and liabilities:
Accounts receivable	24,088		(78,494)		(21,389)
Prepaid expenses and other	(1,822)		98		733
Accounts payable and accrued expenses	9,466		93,224		31,136
Net cash provided by operating activities	1,456,575		1,338,514		921,969
Cash flows from investing activities:
Net proceeds from sale of oil and gas properties	43,858		424,849		55,375
Capital expenditures	(1,974,798)		(1,553,536)		(1,507,828)
Acquisition of proved and unproved oil and gas properties	(544,553)		(61,603)		(5,773)
Other	(3,256)		(2,613)		893
Net cash used in investing activities	(2,478,749)		(1,192,903)		(1,457,333)
Cash flows from financing activities:
Proceeds from credit facility	1,285,500		1,203,000		1,609,000
Repayment of credit facility	(1,119,500)		(1,543,000)		(1,269,000)
Debt issuance costs related to credit facility	(3,388)		(3,444)		0
Net proceeds from Senior Notes	589,991		490,185		392,138
Repayment of 3.50% Senior Convertible Notes	0		0		(287,500)
Proceeds from sale of common stock	4,877		6,858		5,816
Dividends paid	(6,723)		(6,663)		(6,511)
Net share settlement from issuance of stock awards	(10,624)		(16,220)		(21,622)
Other	(87)		(5)		(225)
Net cash provided by financing activities	740,046		130,711		422,096
Net change in cash and cash equivalents	(282,128)		276,322		(113,268)
Cash and cash equivalents at beginning of period	282,248		5,926		119,194
Cash and cash equivalents at end of period	120		282,248		5,926
Supplemental schedule of additional cash flow information and noncash investing and financing activities:
Interest Paid, Net	89,145		70,702		51,328
Net cash refunded for income taxes	$ 1,936		$ (204)		$ (1,389)

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