Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash Flows from Operating Activities of Continuing Operations:
Net income	$ 16,729	$ 49,565	$ 37,588	$ 107,750
Adjustments to reconcile net income to net cash provided by operating activities of continuing operations -
Income from discontinued operations		(14,102)		(19,897)
Depreciation	42,759	41,030	83,929	80,428
Amortization of intangible assets	8,141	8,731	15,636	17,024
Equity in losses of unconsolidated affiliates	378	314	559	314
Amortization of debt issuance costs	338	273	678	546
(Gain) loss on sale of property and equipment	654	(7)	547	(110)
Foreign currency loss	558	523	668	713
Provision for (recovery of) doubtful accounts	56	126	(927)	704
Deferred income tax provision (benefit)	(7,858)	280	(5,142)	992
Non-cash stock-based compensation	9,503	9,714	23,222	19,185
Tax impact of stock-based equity awards	(122)	(3)	(122)	(4)
Changes in operating assets and liabilities, net of non-cash transactions - (Increase) decrease in -
Accounts and notes receivable	105,399	17,779	264,394	137,652
Costs and estimated earnings in excess of billings on uncompleted contracts	(82,456)	(3,281)	(134,923)	(66,769)
Inventories	(2,256)	(9,869)	2,281	(12,991)
Prepaid expenses and other current assets	(13,513)	(7,270)	(11,687)	(9,576)
Accounts payable and accrued expenses and other non-current liabilities	32,808	22,235	3,092	51,446
Billings in excess of costs and estimated earnings on uncompleted contracts	(48,465)	(7,551)	(12,527)	(14,569)
Other, net	3,875	(2,363)	(999)	(7,086)
Net cash provided by operating activities of continuing operations	66,528	106,124	266,267	285,752
Cash Flows from Investing Activities of Continuing Operations:
Proceeds from sale of property and equipment	5,165	7,733	10,254	9,015
Additions of property and equipment	(60,855)	(62,493)	(108,550)	(120,997)
Cash paid for acquisitions, net of cash acquired	(35)	(37,936)	(39,710)	(72,669)
Investments in and return of equity from unconsolidated affiliates	(3,163)	(1,784)	(5,388)	(2,593)
Cash received from (paid for) other investments, net	503	2,871	1,080	3,193
Cash withdrawn from restricted cash	42		42	214
Cash paid for intangibles		(211)		(211)
Net cash used in investing activities of continuing operations	(58,343)	(91,820)	(142,272)	(184,048)
Cash Flows from Financing Activities of Continuing Operations:
Borrowings under credit facility	696,572	625,286	1,350,988	772,742
Payments under credit facility	(696,668)	(528,741)	(1,426,271)	(632,684)
Payments on other long-term debt	(692)	(959)	(5,547)	(1,359)
Payments on short-term debt		(4,248)	(4,711)	(5,170)
Distributions to non-controlling interests		(2,500)		(5,003)
Tax impact of stock-based equity awards	122	3	122	4
Exercise of stock options	163	278	214	354
Repurchase of common stock		(172,279)		(354,279)
Net cash used in financing activities of continuing operations	(503)	(83,160)	(85,205)	(225,395)
Discontinued operations:
Net cash provided by operating activities		11,432		21,031
Net cash used in investing activities	(437)	(13,517)	(6,080)	(21,181)
Net cash used in discontinued operations	(437)	(2,085)	(6,080)	(150)
Effect of foreign exchange rate changes on cash and cash equivalents	(216)	834	863	(1,247)
Net increase (decrease) in cash and cash equivalents	7,029	(70,107)	33,573	(125,088)
Cash and cash equivalents, beginning of period	155,315	135,534	128,771	190,515
Cash and cash equivalents, end of period	162,344	65,427	162,344	65,427
Supplemental disclosure of cash flow information:
Interest paid related to continuing operations	(3,066)	(1,422)	(5,507)	(2,610)
Income taxes paid	(27,038)	(37,837)	(33,524)	(50,241)
Income tax refunds related to continuing operations	785	10,293	1,679	10,738
Discontinued Operations [Member]
Supplemental disclosure of cash flow information:
Income taxes paid	$ (437)	$ (39)	$ (6,080)	$ (244)