CONDENSED CONSOLIDATED BALANCE SHEET (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Jun. 30, 2013	Dec. 31, 2012		Sep. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 243,075			$ 279,526		$ 176,186	$ 38,451
Accounts receivable	189,565			167,288
Fair value of hedging contracts	14,423			39,655
Current income tax receivable	10,893			10,027
Deferred taxes	26,350	[1]		15,514	[1]
Inventory	3,843			4,207
Other current assets	1,439			3,626
Total current assets	489,588			519,843
Oil and gas properties, full cost method of accounting:
Proved	7,589,153			7,244,466
Less: accumulated depreciation, depletion and amortization	(5,762,937)			(5,510,166)
Net proved oil and gas properties	1,826,216			1,734,300
Unevaluated	576,395			447,795
Other property and equipment, net	23,965			22,115
Fair value of hedging contracts	5,114			9,199
Other assets, net	49,148			43,179
Total assets	2,970,426			2,776,431
Current liabilities:
Accounts payable to vendors	104,486			94,361
Undistributed oil and gas proceeds	42,913			23,414
Accrued interest	14,272			18,546
Fair value of hedging contracts	8,261			149
Asset retirement obligations	60,938			66,260
Other current liabilities	21,680			16,765
Total current liabilities	252,550			219,495
Long-term debt	923,745			914,126
Deferred taxes	387,033	[1]		310,830	[1]
Asset retirement obligations	407,712			422,042
Fair value of hedging contracts	360			1,530
Other long-term liabilities	26,463			36,275
Total liabilities	1,997,863			1,904,298
Commitments and contingencies
Stockholders' equity:
Common stock, $.01 par value; authorized 100,000,000 shares; issued 48,750,533 and 48,392,552 shares, respectively	488			484
Treasury stock (16,582 shares, at cost)	(860)			(860)
Additional paid-in capital	1,393,439			1,386,475
Accumulated deficit	(426,917)			(542,799)
Accumulated other comprehensive income	6,413		24,500	28,833
Total stockholders' equity	972,563			872,133
Total liabilities and stockholders' equity	$ 2,970,426			$ 2,776,431

[1] Deferred income taxes have been allocated to the Guarantor Subsidiary where related oil and gas properties reside.