Condensed Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 26,463	$ 40,627
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	49,940	42,904
Non-cash interest expense, net	725	870
Non-cash stock-based compensation expense	3,182	3,773
(Benefit from) provision for deferred income taxes	(7,243)	8,403
Equity in earnings of unconsolidated affiliates	(5,585)	(1,646)
Gains on sales of assets, net, including fixed assets held-for-sale	(2,758)	(57)
Other non-cash items, net	544	288
Changes in assets and liabilities, net of acquisitions:
Accounts receivable, net	(97,240)	73,723
Inventories	(651)	21,404
Other assets, current and long-term portion	55,033	2,190
Accounts payable and accrued expenses	26,351	(74,121)
Billings in excess of costs and earnings	16,888	19,612
Book overdrafts	6,123	(2,187)
Other liabilities, current and long-term portion	11,729	18,390
Net cash provided by operating activities	83,501	154,173
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(4,329)	0
Capital expenditures	(22,545)	(28,901)
Proceeds from sale of property and equipment	5,382	511
Payments for other investments	(14,779)	(53,347)
Proceeds from other investments	5,415	12,118
Net cash used in investing activities	(30,856)	(69,619)
Cash flows from financing activities:
Proceeds from credit facilities	816,888	361,743
Repayments of credit facilities	(747,099)	(447,112)
Repayments of other borrowings	(14,612)	(1,499)
Payments of capital lease obligations	(18,112)	(12,912)
Repurchase of common stock	(90,880)	0
Distributions to non-controlling interests	(559)	(1,280)
Proceeds from stock-based awards, net	916
Payments for stock-based awards, net		(761)
Other financing activities	0	(5,973)
Net cash used in financing activities	(53,458)	(107,794)
Effect of currency translation on cash	722	160
Net decrease in cash and cash equivalents	(91)	(23,080)
Cash and cash equivalents - beginning of period	40,326	38,767
Cash and cash equivalents - end of period	40,235	15,687
Supplemental cash flow information:
Interest paid	21,355	18,023
Income tax (refunds) payments, net	(28,738)	1,772
Supplemental disclosure of non-cash information:
Equipment acquired under capital lease and financing arrangements	25,755	33,916
Accrued capital expenditures	4,629	1,029
Earn-Out Liabilities [Member]
Supplemental disclosure of non-cash information:
Additions to acquisition-related contingent consideration	$ 4,161	$ 0