CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 255,514	$ 245,029
Accounts receivable, net of allowance for doubtful accounts of $5,901 and $2,312 at June 30, 2019 and December 31, 2018, respectively	501,206	558,817
Federal and state income taxes receivable	5,954	4,110
Inventory	68,611	65,579
Other	66,459	76,662
Total current assets	897,744	950,197
Property and equipment, net	3,769,258	4,002,549
Right of use asset	26,665
Goodwill and intangible assets	472,413	477,640
Deposits on equipment purchases	7,312	12,040
Other	18,391	27,440
Total assets	5,191,783	5,469,866
Current liabilities:
Accounts payable	242,166	288,962
Federal and state income taxes payable	269	1,408
Accrued liabilities	218,632	235,946
Lease liability	8,977
Total current liabilities	470,044	526,316
Long-term lease liability	22,355
Long-term debt, net of debt discount and issuance costs of $5,352 and $5,795 at June 30, 2019 and December 31, 2018, respectively	1,119,648	1,119,205
Deferred tax liabilities, net	291,294	306,161
Other	10,131	12,761
Total liabilities	1,913,472	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 268,790,705 and 267,315,526 issued and 202,401,130 and 213,614,430 outstanding at June 30, 2019 and December 31, 2018, respectively	2,688	2,673
Additional paid-in capital	2,856,746	2,827,154
Retained earnings	1,658,417	1,753,557
Accumulated other comprehensive income	4,279	2,487
Treasury stock, at cost, 66,389,575 and 53,701,096 shares at June 30, 2019 and December 31, 2018, respectively	(1,243,819)	(1,080,448)
Total stockholders' equity	3,278,311	3,505,423
Total liabilities and stockholders' equity	$ 5,191,783	$ 5,469,866