CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 35,152	$ 113,346
Accounts receivable, net of allowance for doubtful accounts of $3,191 and $3,545 at December 31, 2016 and 2015, respectively	148,091	219,672
Federal and state income taxes receivable	2,126	33,454
Inventory	20,191	14,716
Deferred tax assets, net	36,439	65,121
Other	41,322	40,227
Total current assets	283,321	486,536
Property and equipment, net	3,408,963	3,920,708
Goodwill and intangible assets	88,966	92,609
Deposits on equipment purchases	16,050	22,367
Other	7,306	7,264
Total assets	3,804,606	4,529,484
Current liabilities:
Accounts payable	125,667	82,771
Accrued expenses	139,148	161,611
Current portion of long-term debt, net of debt issuance cost of $483 at December 31, 2015		63,267
Total current liabilities	264,815	307,649
Long-term debt, net of debt issuance cost of $1,563 and $3,350 at December 31, 2016 and 2015, respectively	598,437	787,900
Deferred tax liabilities, net	682,976	863,833
Other	9,654	8,971
Total liabilities	1,555,882	1,968,353
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 191,525,872 and 190,374,801 issued and 148,133,255 and 147,167,561 outstanding at December 31, 2016 and 2015, respectively	1,915	1,904
Additional paid-in capital	1,042,696	1,011,811
Retained earnings	2,116,341	2,458,554
Accumulated other comprehensive loss	(1,134)	(4,093)
Treasury stock, at cost, 43,392,617 shares and 43,207,240 shares at December 31, 2016 and 2015, respectively	(911,094)	(907,045)
Total stockholders’ equity	2,248,724	2,561,131
Total liabilities and stockholders’ equity	$ 3,804,606	$ 4,529,484