CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 252	$ 92
Accounts receivable, less allowance for doubtful accounts of $2,374 and $4,015	167,495	127,180
Unrealized derivative gain	137,552	173,921
Inventory and other	22,315	14,070
Total current assets	327,614	315,263
Unrealized derivative gain	15,715	77,579
Equity method investments	132,449	138,130
Natural gas and oil properties, successful efforts method	8,111,775	6,784,027
Accumulated depletion and depreciation	(2,015,591)	(1,626,461)
Natural gas and oil properties, successful efforts method, net	6,096,184	5,157,566
Transportation and field assets	117,717	123,349
Accumulated depreciation and amortization	(76,150)	(70,671)
Transportation and field assets, net	41,567	52,678
Other assets	115,206	104,254
Total assets	6,728,735	5,845,470
Current liabilities:
Accounts payable	234,651	311,369
Asset retirement obligations	2,470	5,005
Accrued liabilities	139,379	109,109
Liabilities of discontinued operations		653
Deferred tax liability	37,924	56,595
Accrued interest	36,248	29,201
Unrealized derivative loss	4,471
Total current liabilities	455,143	511,932
Bank debt	739,000	187,000
Subordinated notes	2,139,185	1,787,967
Deferred tax liability	698,302	710,490
Unrealized derivative loss	3,463	173
Deferred compensation liability	187,604	169,188
Asset retirement obligations and other liabilities	148,646	86,300
Total liabilities	4,371,343	3,453,050
Commitments and contingencies
Stockholders' Equity
Preferred stock, $1 par, 10,000,000 shares authorized, none issued and outstanding
Common stock, $0.01 par, 475,000,000 shares authorized, 162,641,896 issued at December 31, 2012 and 161,302,973 issued at December 31, 2011	1,626	1,613
Common stock held in treasury, 127,798 shares at December 31, 2012 and 171,426 shares at December 31, 2011	(4,760)	(6,343)
Additional paid-in capital	1,915,627	1,866,554
Retained earnings	360,990	373,969
Accumulated other comprehensive income	83,909	156,627
Total stockholders' equity	2,357,392	2,392,420
Total liabilities and stockholders' equity	$ 6,728,735	$ 5,845,470