Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 107,416,000		$ 105,972,000		$ 90,387,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	92,601,000		75,228,000		57,966,000
Stock-based compensation expense	4,433,000		3,573,000		3,872,000
Excess tax benefit from stock-based compensation	(759,000)	[1]	(7,766,000)	[1]	0	[1]
Non-cash interest expense	8,595,000		7,552,000		3,252,000
Provision for doubtful accounts	6,970,000		2,016,000		2,895,000
Provision for inventory obsolescence	2,335,000		3,085,000		300,000
Impairment of securities available for sale	0		574,000		1,164,000
(Gain) loss on sale of assets	(1,208,000)		(76,000)		(907,000)
Estimated losses on disposal of businesses, including impairment charges	12,922,000		0		0
Gain on remeasurement of equity interest in acquiree	0		(29,041,000)		0
Changes in assets and liabilities, net of assets acquired and liabilities assumed:
Accounts receivable	(177,313,000)		(180,839,000)		(127,724,000)
Inventories	15,448,000		(30,527,000)		(25,363,000)
Deferred tax assets and liabilities, net	3,775,000		22,696,000		56,360,000
Other assets, current and non-current portion	(6,383,000)		(23,453,000)		(5,293,000)
Accounts payable and accrued expenses	76,285,000		73,099,000		67,137,000
Billings in excess of costs and earnings	15,651,000		(34,712,000)		86,201,000
Other liabilities, current and non-current portion	21,016,000		7,936,000		7,348,000
Net cash provided by (used in) operating activities	172,135,000		5,826,000		218,029,000
Cash flows provided by (used in) investing activities:
Cash paid for acquisitions, net, including contingent consideration	(153,138,000)		(85,395,000)		(75,896,000)
Payments to acquire equity method investees	0		0		10,854,000
Capital expenditures	(79,686,000)		(71,710,000)		(30,383,000)
Proceeds from sale of assets	7,385,000		6,227,000		7,037,000
Proceeds from disposal of business, net	97,728,000		0		0
Payments to acquire other investments	0		0		750,000
Proceeds from sale or redemption of investments	0		4,600,000		7,044,000
Investments in life insurance policies	(284,000)		(284,000)		(478,000)
Net cash provided by (used in) investing activities	(127,995,000)		(146,562,000)		(104,280,000)
Cash flows (used in) provided by financing activities:
Proceeds from credit facility	959,183,000		370,411,000		0
Repayments of credit facility	(885,183,000)		(310,411,000)		0
Proceeds from other borrowings	0		0		13,543,000
Repayments of other borrowings	(21,455,000)		(13,956,000)		(27,170,000)
Proceeds from book overdrafts	116,000		14,906,000		0
Payments of capital lease obligations	(21,060,000)		(16,458,000)		(14,460,000)
Proceeds from stock option exercises and other share-based awards	5,013,000		12,542,000		3,515,000
Excess tax benefit from stock-based compensation	759,000		7,766,000		0
Purchases of treasury stock	(75,000,000)		(75,000,000)		0
Payments of financing costs	(117,000)		(6,589,000)		(169,000)
Net cash (used in) provided by financing activities	(37,744,000)		(16,789,000)		(24,741,000)
Net (decrease) increase and cash equivalents	6,396,000		(157,525,000)		89,008,000
Net effect of currency translation on cash	91,000		201,000		75,000
Cash and cash equivalents - beginning of period	20,280,000		177,604,000		88,521,000
Cash and cash equivalents - end of period	26,767,000		20,280,000		177,604,000
Cash and cash equivalents of discontinued operations	385,000		12,874,000		18,911,000
Cash and cash equivalents of continuing operations	26,382,000		7,406,000		158,693,000
Supplemental cash flow information:
Interest paid	27,074,000		27,607,000		27,385,000
Income taxes paid, net of refunds	58,968,000		27,803,000		5,694,000
Supplemental disclosure of noncash information:
Equipment acquired under capital lease	60,648,000		7,412,000		2,243,000
Machinery and Equipment [Member]
Supplemental disclosure of noncash information:
Equipment acquired under financing arrangements	6,009,000		25,788,000		0
Conversion of leases from operating to capital	0		23,366,000		0
Equity Issued in Business Combination [Member]
Supplemental disclosure of noncash information:
Shares issued in connection with business combinations	0		94,213,000		27,045,000
Contracts Accounted for under Percentage of Completion [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for losses on construction projects, net	(9,649,000)		10,509,000		434,000
Inventories [Member]
Supplemental cash flow information:
Receipt of inventory prepaid in prior year	12,005,000		0		0
Total Exchanged Senior Convertible Notes [Member] | Convertible Debt [Member]
Supplemental disclosure of noncash information:
Exchange of senior convertible notes	$ 0		$ 202,322,000		$ 0

[1] Excess tax benefits, which represent cash flows from tax deductions in excess of compensation expense recognized for stock options exercised and vested restricted shares, are classified as financing cash flows in the Company’s consolidated statements of cash flows.