CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 76,465	$ 43,012
Accounts receivable, net of allowance for doubtful accounts of $3,537 and $3,546 at September 30, 2015 and December 31, 2014, respectively	301,710	663,404
Federal and state income taxes receivable	30,952	81,726
Inventory	17,422	32,251
Deferred tax assets, net	37,809	37,075
Other	41,383	51,624
Total current assets	505,741	909,092
Property and equipment, net	4,023,199	4,131,071
Goodwill and intangible assets	93,520	220,813
Deposits on equipment purchases	35,863	112,379
Other	19,843	20,656
Total assets	4,678,166	5,394,011
Current liabilities:
Accounts payable	165,547	382,438
Accrued expenses	180,530	173,466
Current portion of long-term debt	50,000	12,500
Total current liabilities	396,077	568,404
Borrowings under revolving credit facility		303,000
Other long-term debt	815,000	670,000
Deferred tax liabilities, net	826,163	935,660
Other	9,829	11,137
Total liabilities	$ 2,047,069	$ 2,488,201
Commitments and contingencies (see Note 9)
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 190,387,622 and 189,262,876 issued and 147,180,382 and 146,444,291 outstanding at September 30, 2015 and December 31, 2014, respectively	$ 1,904	$ 1,893
Additional paid-in capital	1,006,306	984,674
Retained earnings	2,531,923	2,811,815
Accumulated other comprehensive income	(1,991)	6,463
Treasury stock, at cost, 43,207,240 shares and 42,818,585 shares at September 30, 2015 and December 31, 2014, respectively	(907,045)	(899,035)
Total stockholders' equity	2,631,097	2,905,810
Total liabilities and stockholders' equity	$ 4,678,166	$ 5,394,011