Condensed Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 188,160	$ 78,086
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	138,384	122,249
Non-cash interest expense, net	2,375	2,209
Non-cash stock-based compensation expense	10,551	11,291
Provision for (benefit from) deferred income taxes	92,188	(1,339)
Equity in earnings of unconsolidated affiliates	(15,105)	(3,549)
(Gains) losses on sales of assets, net, including fixed assets held-for-sale	(3,335)	378
Other non-cash items, net	14,920	1,951
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	(334,383)	(302,590)
Inventories	33,579	(18,900)
Other assets, current and long-term portion	(61,900)	48,032
Accounts payable and accrued expenses	132,963	172,731
Billings in excess of costs and earnings	(54,199)	16,581
Book overdrafts	(4,603)	8,883
Other liabilities, current and long-term portion	39,030	(8,872)
Net cash provided by operating activities	178,625	127,141
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(115,995)	(4,102)
Capital expenditures	(83,330)	(89,050)
Proceeds from sale of property and equipment	13,585	6,824
Payments for other investments	(77,105)	(8,858)
Proceeds from other investments	13,416	1,125
Net cash used in investing activities	(249,429)	(94,061)
Cash flows from financing activities:
Proceeds from credit facilities	2,002,430	1,186,816
Repayments of credit facilities	(1,840,409)	(1,149,930)
Repayments of other borrowings	(12,080)	(8,188)
Payments of capital lease obligations	(48,748)	(41,828)
Payments of acquisition-related contingent consideration	(18,843)	(19,822)
Distributions to non-controlling interests	(1,280)	0
Proceeds from stock-based awards, net	853	3,938
Other financing activities, net	(6,301)	1,385
Net cash provided by (used in) financing activities	75,622	(27,629)
Effect of currency translation on cash	237	(1,008)
Net increase in cash and cash equivalents	5,055	4,443
Cash and cash equivalents - beginning of period	38,767	4,984
Cash and cash equivalents - end of period	43,822	9,427
Supplemental cash flow information:
Interest paid	47,163	40,433
Income taxes paid, net of refunds	77,533	15,141
Equipment acquired under capital lease and financing arrangements	129,567	13,015
Accrued capital expenditures	1,345	4,119
Earn-Out Arrangements [Member]
Acquisition-related contingent consideration, new business combinations	$ 89,614	$ 0