CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 117,634	$ 149,426	$ 194,332
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	350,574	344,365	280,020
Accretion expense	33,575	33,331	30,764
Deferred income tax provision	79,629	69,575	129,520
Settlement of asset retirement obligations	(83,854)	(65,567)	(63,391)
Non-cash stock compensation expense	10,347	8,699	5,905
Excess tax benefits	(156)	(949)	(1,493)
Non-cash derivative expense (income)	2,239	(509)	(2,216)
Loss on early extinguishment of debt	27,279	1,972	607
Non-cash interest expense	16,219	13,085	1,908
Other non-cash income			(1,602)
Change in current income taxes	2,767	10,618	(19,451)
Increase in accounts receivable	(4,683)	(55,871)	(19,600)
(Increase) decrease in other current assets	1,752	(2,836)	(66)
Decrease in inventory	583	436	1,619
Increase in accounts payable	402	5,101	6,039
Increase (decrease) in other current liabilities	42,451	(10,426)	29,583
Other	(2,553)	9,299	(1,628)
Net cash provided by (used in) operating activities	594,205	509,749	570,850
Cash flows from investing activities:
Investment in oil and gas properties	(663,299)	(555,855)	(764,933)
Proceeds from sale of oil and gas properties, net of expenses	48,821	403	87,930
Sale of fixed assets		134
Investment in fixed and other assets	(6,816)	(13,370)	(2,247)
Change in restricted funds	(1,742)
Net cash used in investing activities	(623,036)	(568,688)	(679,250)
Cash flows from financing activities:
Proceeds from bank borrowings		25,000	75,000
Repayments of bank borrowings		(70,000)	(30,000)
Proceeds from issuance of senior convertible notes		300,000
Deferred financing costs of senior convertible notes		(8,855)
Proceeds from sold warrants		40,170
Payments for purchased call options		(70,830)
Proceeds from issuance of senior notes	489,250	300,000
Deferred financing costs	(9,065)	(11,966)	(4,017)
Redemption of senior notes	(396,014)
Redemption of senior subordinated notes		(200,681)
Excess tax benefits	156	949	1,493
Net payments for share-based compensation	(3,733)	(3,773)	(2,581)
Net cash provided by financing activities	80,594	300,014	39,895
Effect of exchange rate changes on cash	(65)
Net change in cash and cash equivalents	51,698	241,075	(68,505)
Cash and cash equivalents, beginning of period	279,526	38,451	106,956
Cash and cash equivalents, end of period	331,224	279,526	38,451
Supplemental cash flow information:
Interest, net of amount capitalized	(29,883)	(20,150)	(9,808)
Income taxes	$ 13,670	$ (4,405)	$ 935