CONSOLIDATED STATEMENT 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)	$ (1,090,915)	$ (189,543)	$ 117,634
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	281,688	340,006	350,574
Write-down of oil and gas properties	1,362,447	351,192	0
Accretion expense	25,988	28,411	33,575
Deferred income tax (benefit) provision	(272,311)	(102,177)	79,629
Settlement of asset retirement obligations	(72,382)	(56,409)	(83,854)
Non-cash stock compensation expense	12,324	11,325	10,347
Excess tax benefits	(1,586)	0	(156)
Non-cash derivative (income) expense	16,440	(18,028)	2,239
Loss on early extinguishment of debt	0	0	27,279
Non-cash interest expense	17,788	16,661	16,219
Change in current income taxes	(37,377)	158	2,767
(Increase) decrease in accounts receivable	43,724	51,611	(4,683)
(Increase) decrease in other current assets	1,767	(6,244)	1,752
Decrease in inventory	1,304	0	583
Increase (decrease) in accounts payable	(14,582)	(3,419)	402
Increase (decrease) in other current liabilities	(25,936)	(19,152)	42,451
Other	(907)	(3,251)	(2,553)
Net cash provided by operating activities	247,474	401,141	594,205
Cash flows from investing activities:
Investment in oil and gas properties	(522,047)	(927,247)	(663,299)
Proceeds from sale of oil and gas properties, net of expenses	22,839	242,914	48,821
Investment in fixed and other assets	(1,549)	(10,182)	(6,816)
Change in restricted funds	179,467	(178,072)	(1,742)
Net cash used in investing activities	(321,290)	(872,587)	(623,036)
Cash flows from financing activities:
Proceeds from bank borrowings	5,000	0	0
Repayments of bank borrowings	(5,000)	0	0
Proceeds from building loan	11,770	0	0
Proceeds from issuance of senior notes	0	0	489,250
Net proceeds from issuance of common stock	0	225,999	0
Deferred financing costs	(68)	(3,371)	(9,065)
Redemption of senior notes	0	0	(396,014)
Excess tax benefits	1,586	0	156
Net payments for share-based compensation	(3,127)	(7,182)	(3,733)
Net cash provided by financing activities	10,161	215,446	80,594
Effect of exchange rate changes on cash	(74)	(736)	(65)
Net change in cash and cash equivalents	(63,729)	(256,736)	51,698
Cash and cash equivalents, beginning of year	74,488	331,224	279,526
Cash and cash equivalents, end of year	10,759	74,488	331,224
Supplemental cash flow information:
Cash paid for interest, net of amount capitalized	(34,394)	(14,076)	(29,883)
Cash (paid) refunded for income taxes	$ 7,212	$ (1)	$ 13,670