CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 248,901	$ 245,029
Accounts receivable, net of allowance for doubtful accounts of $2,307 and $2,312 at March 31, 2019 and December 31, 2018, respectively	547,993	558,817
Federal and state income taxes receivable	4,083	4,110
Inventory	65,871	65,579
Other	60,883	76,662
Total current assets	927,731	950,197
Property and equipment, net	3,898,518	4,002,549
Right of use asset	28,405
Goodwill and intangible assets	476,078	477,640
Deposits on equipment purchases	10,505	12,040
Other	26,515	27,440
Total assets	5,367,752	5,469,866
Current liabilities:
Accounts payable	260,378	288,962
Federal and state income taxes payable	1,367	1,408
Accrued expenses	240,196	235,946
Lease liability	9,217
Total current liabilities	511,158	526,316
Long-term lease liability	23,903
Long-term debt, net of debt discount and issuance costs of $5,574 and $5,795 at March 31, 2019 and December 31, 2018, respectively	1,119,426	1,119,205
Deferred tax liabilities, net	299,557	306,161
Other	10,339	12,761
Total liabilities	1,964,383	1,964,443
Commitments and contingencies (see Note 10)
Stockholders' equity:
Preferred stock, par value $.01; authorized 1,000,000 shares, no shares issued
Common stock, par value $.01; authorized 400,000,000 shares with 267,353,108 and 267,315,526 issued and 208,243,640 and 213,614,430 outstanding at March 31, 2019 and December 31, 2018, respectively	2,673	2,673
Additional paid-in capital	2,836,492	2,827,154
Retained earnings	1,716,334	1,753,557
Accumulated other comprehensive income	3,431	2,487
Treasury stock, at cost, 59,109,468 and 53,701,096 shares at March 31, 2019 and December 31, 2018, respectively	(1,155,561)	(1,080,448)
Total stockholders' equity	3,403,369	3,505,423
Total liabilities and stockholders' equity	$ 5,367,752	$ 5,469,866