Condensed Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 43,107	$ 26,463
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	59,031	49,940
Non-cash interest expense, net	453	725
Non-cash stock-based compensation expense	3,720	3,182
Provision for (benefit from) deferred income taxes	899	(7,243)
Equity in earnings of unconsolidated affiliates	(6,260)	(5,585)
Gains on sales of assets, net, including fixed assets held-for-sale	(2,052)	(2,758)
Other non-cash items, net	(3,043)	544
Changes in assets and liabilities, net of acquisitions:
Accounts receivable, net	(31,455)	(97,240)
Inventories	9,690	(651)
Other assets, current and long-term portion	2,398	55,033
Accounts payable and accrued expenses	(134,491)	32,474
Billings in excess of costs and earnings	3,821	16,888
Other liabilities, current and long-term portion	7,375	11,729
Net cash (used in) provided by operating activities	(46,807)	83,501
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(93,684)	(4,329)
Capital expenditures	(34,396)	(22,545)
Proceeds from sale of property and equipment	8,654	5,382
Payments for other investments	(2,190)	(14,779)
Proceeds from other investments	10,413	5,415
Net cash used in investing activities	(111,203)	(30,856)
Cash flows from financing activities:
Proceeds from credit facilities	866,397	816,888
Repayments of credit facilities	(670,794)	(747,099)
Repayments of other borrowings, net	(6)	(14,612)
Payments of finance lease obligations	(17,239)	(18,112)
Distributions to non-controlling interests	0	(559)
Proceeds from stock-based awards, net	1,067	916
Repurchases of common stock	(5,652)	(90,880)
Net cash provided by (used in) financing activities	173,773	(53,458)
Effect of currency translation on cash	9	722
Net increase (decrease) in cash and cash equivalents	15,772	(91)
Cash and cash equivalents - beginning of period	27,422	40,326
Cash and cash equivalents - end of period	43,194	40,235
Supplemental cash flow information:
Interest paid	26,220	21,355
Income tax payments (refunds), net	2,837	(28,738)
Supplemental disclosure of non-cash information:
Additions to property and equipment from finance leases	$ 40,258	$ 25,755