CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) (in thousands, except per share amounts) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Operating revenues:
Oil, gas, and NGL production revenue	$ 617,207		$ 601,787		$ 1,894,977		$ 1,605,882
Other operating revenues	1,579		11,320		31,509		50,765
Total operating revenues	618,786		613,107		1,926,486		1,656,647
Operating expenses:
Oil, gas, and NGL production expense	178,390		158,921		519,697		434,291
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	183,259		195,792		548,255		620,232
Exploration	34,556		16,280		80,161		52,335
Impairment of proved properties	0		5,935		0		61,706
Abandonment and impairment of unproved properties	15,522		3,818		18,487		8,459
General and administrative	41,696		33,920		114,862		101,574
Change in Net Profits Plan liability	(6,399)		940		(15,280)		(6,423)
Derivative (gain) loss	(190,661)	[1]	39,933	[1]	33,470	[1]	(14,685)	[1]
Other operating expenses	5,444		20,084		19,505		71,192
Total operating expenses	261,807		475,623		1,319,157		1,328,681
Income from operations	356,979		137,484		607,329		327,966
Non-operating income (expense):
Interest expense	(22,621)		(24,488)		(70,851)		(65,170)
Other, net	(672)		28		(2,493)		64
Income before income taxes	333,686		113,024		533,985		262,860
Income tax expense	(124,748)		(42,334)		(199,660)		(98,921)
Net income	$ 208,938		$ 70,690		$ 334,325		$ 163,939
Basic weighted-average common shares outstanding	67,379		66,943		67,169		66,486
Diluted weighted-average common shares outstanding	68,430		68,253		68,258		67,969
Basic net income per common share	$ 3.10		$ 1.06		$ 4.98		$ 2.47
Diluted net income per common share	$ 3.05		$ 1.04		$ 4.90		$ 2.41
Dividends per common share	$ 0.05		$ 0.05		$ 0.10		$ 0.10

[1] (2) Total derivative (gain) loss is reported in the derivative (gain) loss line item on the condensed consolidated statements of cash flows within net cash provided by operating activities.