CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Operating Revenues:
Gas sales	$ 504,496		$ 462,134
Gas marketing	179,841		148,051
Oil sales	5,350		2,528
Gas gathering	43,962		42,122
Total Operating Revenues	733,649		654,835
Operating Costs and Expenses:
Gas purchases - midstream services	179,956		146,676
Operating expenses	64,224		60,958
General and administrative expenses	37,215		48,826
Depreciation, depletion and amortization	179,467		193,627
Taxes, other than income taxes	20,827		20,422
Total operating costs and expenses	481,689		470,509
Operating income	251,960		184,326
Interest Expense:
Interest on debt	24,097		19,735
Other interest charges	1,110		991
Interest capitalized	(16,186)		(13,388)
Total Interest Expense	9,021	[1]	7,338	[1]
Other income (loss), net	(533)		(200)
Commodity Derivative Income (Loss)	(29,794)		1,634
Income Before Income Taxes	212,612		178,422
Provision for Income Taxes:
Current	136		168
Deferred	84,961		70,550
Total provision for income taxes	85,097	[1]	70,718	[1]
Net Income	$ 127,515		$ 107,704
Earnings Per Share:
Basic	$ 0.36		$ 0.31
Diluted	$ 0.36		$ 0.31
Weighted Average Common Shares Outstanding:
Basic	350,032,430		348,000,074
Diluted	350,738,309	[2]	349,990,725	[2]

[1] Interest expense and the provision for income taxes by segment are allocated as they are incurred at the corporate level.

[2] Options for 2,112,679 shares and 271,674 shares of restricted stock were excluded from the calculation for the three months ended March 31, 2013 because they would have had an antidilutive effect. Options for 1,702,166 shares and 657,763 shares of restricted stock were excluded from the calculation for the three months ended March 31, 2012 because they would have had an antidilutive effect.