Consolidated Statements of Income and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues:
Gas sales	$ 172,503	$ 126,547	$ 342,600	$ 227,668
Oil sales	354,882	304,466	679,953	561,998
NGL sales	95,470	52,309	185,427	109,184
Gas gathering and other	14,284	10,844	26,748	21,571
Gas marketing, net	(470)	(409)	1,157	(308)
Total revenues	636,669	493,757	1,235,885	920,113
Costs and expenses:
Depreciation, depletion and amortization	194,989	147,231	368,920	283,669
Asset retirement obligation	3,650	2,884	6,868	5,283
Production	86,085	69,433	161,226	138,819
Transportation, processing and other operating	46,478	22,022	90,726	40,656
Gas gathering and other	10,041	5,184	18,825	11,340
Taxes other than income	32,323	27,807	65,944	52,935
General and administrative	16,571	22,836	37,283	38,413
Stock compensation	3,548	3,507	7,272	7,112
(Gain) loss on derivative instruments, net	2,454	(13,660)	18,189	(12,057)
Other operating, net	112	2,365	215	5,297
Total costs and expenses	396,251	289,609	775,468	571,467
Operating income	240,418	204,148	460,417	348,646
Other (income) and expense:
Interest expense	16,724	14,112	30,766	27,318
Capitalized interest	(8,575)	(7,387)	(15,865)	(16,582)
Other, net	(4,129)	(8,758)	(11,084)	(11,374)
Income before income tax	236,398	206,181	456,600	349,284
Income tax expense	87,758	76,616	169,503	129,792
Net income	148,640	129,565	287,097	219,492
Basic
Distributed (in dollars per share)	$ 0.16	$ 0.14	$ 0.32	$ 0.28
Undistributed (in dollars per share)	$ 1.55	$ 1.36	$ 2.98	$ 2.26
Total basic (in dollars per share)	$ 1.71	$ 1.50	$ 3.30	$ 2.54
Diluted
Distributed (in dollars per share)	$ 0.16	$ 0.14	$ 0.32	$ 0.28
Undistributed (in dollars per share)	$ 1.54	$ 1.35	$ 2.97	$ 2.25
Total diluted (in dollars per share)	$ 1.70	$ 1.49	$ 3.29	$ 2.53
Comprehensive income:
Net income	148,640	129,565	287,097	219,492
Other comprehensive income:
Change in fair value of investments, net of tax	(56)	19	(16)	99
Total comprehensive income	$ 148,584	$ 129,584	$ 287,081	$ 219,591