CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 676,639	$ 779,382
Receivables, net	192,160	225,398
Oil and gas well equipment and supplies	44,648	54,579
Derivative instruments	11,868	10,745
Prepaid expenses	5,425	7,036
Other current assets	350	790
Total current assets	931,090	1,077,930
Oil and gas properties at cost, using the full cost method of accounting:
Proved properties	15,677,599	15,546,948
Unproved properties and properties under development, not being amortized	466,497	440,166
Gross oil and gas properties	16,144,096	15,987,114
Less - accumulated depreciation, depletion, amortization and impairment	(13,057,470)	(12,710,968)
Net oil and gas properties	3,086,626	3,276,146
Fixed assets, net	227,343	230,009
Goodwill	620,232	620,232
Derivative instruments	422	501
Other assets, net	35,548	38,468
Total assets	4,901,261	5,243,286
Current liabilities:
Accounts payable	39,241	66,815
Accrued liabilities	229,787	247,508
Derivative instruments	3,812
Revenue payable	84,252	95,744
Total current liabilities	357,092	410,067
Principal	1,500,000	1,500,000
Less - unamortized debt issuance costs	(13,789)	(14,380)
Long-term debt, net	1,486,211	1,485,620
Deferred income taxes	246,553	352,705
Other liabilities	197,074	197,216
Total liabilities	$ 2,286,930	$ 2,445,608
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.01 par value, 15,000,000 shares authorized, no shares issued
Common stock, $0.01 par value, 200,000,000 shares authorized, 94,815,010 and 94,820,570 shares issued, respectively	$ 948	$ 948
Paid-in capital	2,773,254	2,762,976
Retained earnings (Accumulated deficit)	(160,397)	33,313
Accumulated other comprehensive income	526	441
Total stockholders' equity	2,614,331	2,797,678
Total liabilities and stockholders' equity	$ 4,901,261	$ 5,243,286