Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities:
Net income	$ 10,575	$ 12,605
Noncash items included in net income:
Depreciation and amortization	17,243	15,199
Other, net	1,701	2,060
Changes in operating assets and liabilities, net	(13,213)	(3,704)
Net cash provided by operating activities	16,306	26,160
Investing Activities:
Acquisition of business, net of cash received		(23,080)
Acquisition of property and equipment	(53,995)	(30,064)
Proceeds from disposal of property and equipment	367	294
Net cash used in investing activities	(53,628)	(52,850)
Financing Activities:
Repayment of revolving credit agreement	(26,738)	(72,277)
Borrowing of revolving credit agreement	65,564	93,854
Proceeds from stock option exercises (including excess tax benefits)		1,842
Repayment of capital leases	(1,390)	(446)
Other financing activity		(454)
Net cash provided by financing activities	37,436	22,519
Net Increase (Decrease) in Cash and Cash Equivalents	114	(4,171)
Cash and cash equivalents, beginning of period	124	4,367
Cash and cash equivalents, end of period	238	196
Non Cash Investing Activities
Equipment financed with capital leases	$ 10,032	$ 3,471