Unaudited Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues
Crude oil and natural gas sales	$ 864,538	$ 511,192	$ 1,627,170	$ 1,046,504
Crude oil and natural gas sales to affiliates	27,649	12,201	48,534	29,147
Gain on derivative instruments, net	199,056	471,728	114,225	302,671
Crude oil and natural gas service operations	9,509	9,598	21,052	21,497
Total revenues	1,100,752	1,004,719	1,810,981	1,399,819
Operating costs and expenses
Production expenses	73,143	43,479	134,460	83,495
Production and other expenses to affiliates	1,495	1,427	3,152	2,496
Production taxes and other expenses	81,050	48,077	152,308	97,807
Exploration expenses	11,151	8,702	20,965	12,853
Crude oil and natural gas service operations	7,317	7,255	15,914	17,097
Depreciation, depletion, amortization and accretion	236,790	161,018	450,468	310,473
Property impairments	79,712	35,871	119,793	65,778
General and administrative expenses	35,873	29,813	69,690	54,779
(Gain) loss on sale of assets, net	349	(17,397)	213	(67,024)
Total operating costs and expenses	526,880	318,245	966,963	577,754
Income from operations	573,872	686,474	844,018	822,065
Other income (expense):
Interest expense	(61,378)	(31,691)	(108,853)	(55,969)
Other	634	789	1,180	1,570
Total other income (expense)	(60,744)	(30,902)	(107,673)	(54,399)
Income before income taxes	513,128	655,572	736,345	767,666
Provision for income taxes	189,858	249,888	272,448	292,888
Net income	$ 323,270	$ 405,684	$ 463,897	$ 474,778
Basic net income per share (in dollars per share)	$ 1.76	$ 2.26	$ 2.52	$ 2.64
Diluted net income per share (in dollars per share)	$ 1.75	$ 2.25	$ 2.51	$ 2.63