Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 158	$ 92
Accounts receivable, less allowance for doubtful accounts of $2,783 and $4,015	104,952	127,180
Unrealized derivative gain	251,236	173,921
Inventory and other	15,997	14,070
Total current assets	372,343	315,263
Unrealized derivative gain	97,750	77,579
Equity method investments	135,825	138,130
Natural gas and oil properties, successful efforts method	7,596,430	6,784,027
Accumulated depletion and depreciation	(1,825,390)	(1,626,461)
Natural gas and oil properties, successful efforts method	5,771,040	5,157,566
Transportation and field assets	117,519	123,349
Accumulated depreciation and amortization	(70,901)	(70,671)
Transportation and field assets	46,618	52,678
Other assets	120,318	104,254
Total assets	6,543,894	5,845,470
Current liabilities:
Accounts payable	266,412	311,369
Asset retirement obligations	5,005	5,005
Accrued liabilities	144,765	109,109
Liabilities of discontinued operations		653
Deferred tax liability	82,170	56,595
Accrued interest	38,865	29,201
Unrealized derivative loss	3,283
Total current liabilities	540,500	511,932
Bank debt	235,000	187,000
Subordinated notes	2,388,562	1,787,967
Deferred tax liability	698,429	710,490
Unrealized derivative loss	2,405	173
Deferred compensation liability	170,763	169,188
Asset retirement obligations and other liabilities	91,514	86,300
Total liabilities	4,127,173	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, 162,483,363 issued at June 30, 2012 and 161,302,973 issued at December 31, 2011	1,624	1,613
Common stock held in treasury, 153,806 shares at June 30, 2012 and 171,426 shares at December 31, 2011	(5,655)	(6,343)
Additional paid-in capital	1,888,841	1,866,554
Retained earnings	374,873	373,969
Accumulated other comprehensive income	157,038	156,627
Total stockholders' equity	2,416,721	2,392,420
Total liabilities and stockholders' equity	$ 6,543,894	$ 5,845,470