CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 113,346	$ 43,012
Accounts receivable, net of allowance for doubtful accounts of $3,545 and $3,546 at December 31, 2015 and 2014, respectively	219,672	663,404
Federal and state income taxes receivable	33,454	81,726
Inventory	14,716	32,251
Deferred tax assets, net	65,121	37,075
Other	40,227	51,624
Total current assets	486,536	909,092
Property and equipment, net	3,920,708	4,131,071
Goodwill and intangible assets	92,609	220,813
Deposits on equipment purchases	22,367	112,379
Other	11,097	20,656
Total assets	4,533,317	5,394,011
Current liabilities:
Accounts payable	82,771	382,438
Accrued expenses	161,611	173,466
Current portion of long-term debt	63,750	12,500
Total current liabilities	308,132	568,404
Borrowings under revolving credit facility		303,000
Other long-term debt	791,250	670,000
Deferred tax liabilities, net	863,833	935,660
Other	8,971	11,137
Total liabilities	$ 1,972,186	$ 2,488,201
Commitments and contingencies (see Note 8)
Stockholders’ equity:
Preferred stock, par value $.01; authorized 1,000,000 shares, no shares issued
Common stock, par value $.01; authorized 300,000,000 shares with 190,374,801 and 189,262,876 issued and 147,167,561 and 146,444,291 outstanding at December 31, 2015 and 2014, respectively	$ 1,904	$ 1,893
Additional paid-in capital	1,011,811	984,674
Retained earnings	2,458,554	2,811,815
Accumulated other comprehensive income (loss)	(4,093)	6,463
Treasury stock, at cost, 43,207,240 shares and 42,818,585 shares at December 31, 2015 and 2014, respectively	(907,045)	(899,035)
Total stockholders’ equity	2,561,131	2,905,810
Total liabilities and stockholders’ equity	$ 4,533,317	$ 5,394,011