CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net income	$ 105,180	$ 148,809
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	260,982	204,777
Accretion expense	24,926	23,134
Deferred income tax provision	59,573	97,926
Settlement of asset retirement obligations	(47,211)	(52,543)
Non-cash stock compensation expense	6,800	4,492
Excess tax benefits	(882)	(1,490)
Non-cash derivative income	(584)	(4,337)
Loss on early extinguishment of debt		607
Non-cash interest expense	9,068	1,412
Other non-cash (income) expense	16	(1,362)
Change in current income taxes	(3,240)	(21,710)
Increase in accounts receivable	(15,832)	(17,117)
Increase in other current assets	(2,456)	(185)
Decrease in inventory	136	1,606
Increase in accounts payable	6,116	2,679
Increase (decrease) in other current liabilities	(24,301)	3,604
Other	(4,378)	(1,889)
Net cash provided by (used in) operating activities	373,913	388,413
Cash flows from investing activities:
Investment in oil and gas properties	(445,311)	(430,711)
Proceeds from sale of oil and gas properties, net of expenses	403	7,692
Sale of fixed assets	134
Investment in fixed and other assets	(3,998)	(1,788)
Net cash used in investing activities	(448,772)	(424,807)
Cash flows from financing activities:
Proceeds from bank borrowings	25,000
Repayments of bank borrowings	(70,000)
Proceeds from issuance of senior convertible notes	300,000
Financing costs of senior convertible notes	(8,855)
Proceeds from Sold Warrants	40,170
Payments for Purchased Call Options	(70,830)
Deferred financing costs		(4,017)
Excess tax benefits	882	1,490
Net payments for share based compensation	(3,773)	(2,581)
Net cash provided by (used in) financing activities	212,594	(5,108)
Net change in cash and cash equivalents	137,735	(41,502)
Cash and cash equivalents, beginning of period	38,451	106,956
Cash and cash equivalents, end of period	$ 176,186	$ 65,454