Condensed Consolidated Statement of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 330,373	$ 173,469
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	295,520	205,779
Gain on sale of properties	(187,076)	0
Impairment of oil and gas properties	2,243	762
Deferred income taxes	197,548	102,244
Derivative instruments	(20,253)	41,838
Stock-based compensation expenses	15,755	8,411
Deferred financing costs amortization and other	5,209	2,693
Working capital and other changes:
Change in accounts receivable	(62,581)	(67,487)
Change in inventory	(4,089)	(8,820)
Change in prepaid expenses	(3,179)	(5,175)
Change in other current assets	(1,581)	(138)
Change in other assets	(3,069)	(63)
Change in accounts payable and accrued liabilities	108,788	82,246
Change in other liabilities	(116)	922
Net cash provided by operating activities	673,492	536,681
Cash flows from investing activities:
Capital expenditures	(972,763)	(654,175)
Acquisition of oil and gas properties	(26,126)	(133,061)
Increase in restricted cash	0	(986,210)
Proceeds from sale of properties	324,938	0
Costs related to sale of properties	(2,337)	0
Redemptions of short-term investments	0	25,000
Derivative settlements	(24,773)	(5,135)
Advances from joint interest partners	(6,053)	(7,965)
Net cash used in investing activities	(707,114)	(1,761,546)
Cash flows from financing activities:
Proceeds from issuance of senior notes	0	1,000,000
Proceeds from revolving credit facility	370,000	160,000
Principal payments on revolving credit facility	(355,570)	0
Debt issuance costs	(99)	(21,718)
Purchases of treasury stock	(5,240)	(1,424)
Other	(176)	0
Net cash provided by financing activities	8,915	1,136,858
Decrease in cash and cash equivalents	(24,707)	(88,007)
Cash and cash equivalents:
Beginning of period	91,901	213,447
End of period	67,194	125,440
Supplemental non-cash transactions:
Change in accrued capital expenditures	99,103	10,530
Change in asset retirement obligations	$ 5,134	$ 4,173