CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating activities
Net income (loss)	$ 20,094	$ (37,541)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depletion, depreciation and amortization	61,347	33,843
Deferred income taxes	20,915	7,713
Unsuccessful well costs	9,753	8,270
Change in fair value of derivatives	534	2,045
Cash settlements on derivatives	(4,850)	(2,422)
Equity-based compensation	18,938	21,290
Other	1,396	3,097
Changes in assets and liabilities:
(Increase) decrease in receivables	(2,382)	182,519
(Increase) decrease in inventories	3,637	(5,703)
Increase in prepaid expenses and other	(298)	(213)
Decrease in accounts payable	(80,070)	(72,185)
Increase in accrued liabilities	17,855	4,190
Net cash provided by operating activities	66,869	144,903
Investing activities
Oil and gas assets	(83,491)	(68,070)
Other property	(814)	(3,110)
Restricted cash	886	72
Net cash used in investing activities	(83,419)	(71,108)
Financing activities
Purchase of treasury stock	(82)
Deferred financing costs	(1,243)	(1,599)
Net cash used in financing activities	(1,325)	(1,599)
Net increase (decrease) in cash and cash equivalents	(17,875)	72,196
Cash and cash equivalents at beginning of period	515,164	673,092
Cash and cash equivalents at end of period	497,289	745,288
Cash paid for:
Interest	6,585	10,177
Income taxes	$ 4,300	$ 5,013