Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 105,972	$ 90,387	$ 70,748
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	75,228	57,966	49,539
Stock-based compensation expense	3,573	3,872	3,065
Excess tax benefit from stock-based compensation	(7,766)
Non-cash interest expense	7,552	3,252	2,098
Provision for doubtful accounts	2,016	2,895	2,414
Provision for losses on construction projects, net	10,509	434	1,301
Provision for inventory obsolescence	1,709	300	302
Impairment of securities available for sale	574	1,164	6,119
Gain on disposal of assets	(76)	(907)	(1,334)
(Earnings)/losses on equity method investments	(27)	321
Gain on remeasurement of equity interest in acquiree	(29,041)
Changes in assets and liabilities, net of assets acquired and liabilities assumed:
Accounts receivable	(180,839)	(127,724)	85,044
Inventories	(29,151)	(25,363)	956
Deferred tax assets and liabilities, net	22,696	56,360	8,577
Other assets, current and non-current portion	(23,426)	(5,614)	12,878
Accounts payable and accrued expenses	73,099	67,137	(26,547)
Billings in excess of costs and earnings	(34,712)	86,201	(7,851)
Other liabilities, current and non-current portion	7,936	7,348	(83,170)
Net cash provided by operating activities	5,826	218,029	124,139
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net, including contingent consideration	(85,395)	(75,896)	(157,619)
Payments to acquire equity method investees		(10,854)
Capital expenditures	(71,710)	(30,383)	(21,859)
Proceeds from sale of assets	6,227	7,037	4,171
Payments to acquire other investments		(750)
Proceeds from sales or redemptions of investments	4,600	7,044
Investments in life insurance policies	(284)	(478)	(717)
Net cash used in investing activities	(146,562)	(104,280)	(176,024)
Cash flows (used in) provided by financing activities:
Proceeds from issuance of senior convertible notes			215,000
Proceeds from credit facility	370,411		35,682
Repayments of credit facility	(310,411)		(78,150)
Proceeds from other borrowings and overdrafts incurred	14,906	13,543
Repayments of other borrowings	(13,956)	(27,170)	(71,436)
Payments of capital lease obligations	(16,458)	(14,460)	(2,711)
Proceeds from stock options exercises and other share-based awards	12,542	3,515	3,971
Excess tax benefit from stock-based compensation	7,766
Purchases of treasury stock	(75,000)
Payments of financing costs	(6,589)	(169)	(9,079)
Net cash used in financing activities	(16,789)	(24,741)	93,277
Net (decrease) increase in cash and cash equivalents	(157,525)	89,008	41,392
Net effect of currency translation on cash	201	75	(134)
Cash and cash equivalents - beginning of period	177,604	88,521	47,263
Cash and cash equivalents - end of period	20,280	177,604	88,521
Supplemental cash flow information:
Interest paid	27,607	27,385	22,985
Income taxes paid, net of refunds	27,803	5,694	2,147
Supplemental disclosure of non-cash information:
Equipment acquired under capital lease	7,412	2,243	1,901
Equipment acquired under financing arrangement	25,788
Conversion of leases from operating to capital	23,366
Shares issued for business combinations	$ 94,213	$ 27,045