Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities:
Net income	$ 92,300	$ 79,601
Noncash items included in net income:
Depreciation and amortization	87,258	74,965
Other, net	29,437	14,826
Changes in operating assets and liabilities, net	(1,697)	17,718
Net cash provided by operating activities	207,298	187,110
Investing Activities:
Acquisition of property and equipment	(245,203)	(155,217)
Proceeds from disposal of property and equipment	678	778
Net cash used in investing activities	(244,525)	(154,439)
Financing Activities:
Repayment of revolving credit agreement	(220,985)	(170,733)
Borrowing of revolving credit agreement	270,990	142,733
Proceeds from stock option exercises	2,927	4,165
Shares withheld for taxes	(3,471)	(1,396)
Debt issuance costs	(649)
Repayment of finance leases	(13,764)	(11,631)
Net cash provided by (used in) financing activities	35,048	(36,862)
Net Decrease in Cash and Cash Equivalents	(2,179)	(4,191)
Cash and cash equivalents, beginning of period	2,194	4,720
Cash and cash equivalents, end of period	15	529
Non Cash Investing Activities
Equipment financed with finance leases	$ 6,165	$ 28,052