CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 25,943	$ 40,758
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	82,646	75,435
Accretion expense	7,555	8,263
Deferred income tax provision	15,102	27,024
Settlement of asset retirement obligations	(9,842)	(14,880)
Non-cash stock compensation expense	2,247	2,296
Excess tax benefits		(104)
Non-cash derivative expense	448	1,385
Non-cash interest expense	4,070	4,041
Change in current income taxes		(9,402)
(Increase) decrease in accounts receivable	(18,602)	19,952
Decrease in other current assets	100	40
(Increase) decrease in inventory	(928)	158
Increase in accounts payable	1,293	2,004
Increase (decrease) in other current liabilities	5,820	(8,942)
Other	(380)	(1,262)
Net cash (used in) provided by operating activities	115,472	146,766
Cash flows from investing activities:
Investment in oil and gas properties	(287,175)	(160,968)
Proceeds from sale of oil and gas properties, net of expenses	51,954
Investment in fixed and other assets	(1,654)	(599)
Change in restricted funds	(358)
Net cash used in investing activities	(237,233)	(161,567)
Cash flows from financing activities:
Deferred financing costs	(126)	(11)
Excess tax benefits		104
Net payments for share-based compensation	(6,565)	(3,465)
Net cash used in financing activities	(6,691)	(3,372)
Effect of exchange rate changes on cash	(11)
Net change in cash and cash equivalents	(128,463)	(18,173)
Cash and cash equivalents, beginning of period	331,224	279,526
Cash and cash equivalents, end of period	$ 202,761	$ 261,353