Condensed Unaudited Consolidated Statements Of Cash Flows (USD $)	6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 53,420,000		$ 44,258,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	65,355,000		42,946,000
Stock-based compensation expense	6,617,000		2,171,000
Excess tax benefit from stock-based compensation	(1,462,000)	[1]	(70,000)	[1]
Non-cash interest expense	4,528,000		4,253,000
Write-off of unamortized financing costs on redeemed debt	1,508,000		0
Provision for doubtful accounts	2,491,000		1,275,000
Provision for inventory obsolescence	360,000		976,000
Gain on sale of property and equipment	(1,355,000)		(898,000)
Gain on sale of available for sale securities	(717,000)		0
Impairment charges and loss on disposal, discontinued operations	320,000
Impairment charges and loss on disposal, discontinued operations			248,000
Changes in assets and liabilities, net of assets acquired and liabilities assumed:
Accounts receivable	(178,566,000)		(245,975,000)
Inventories	17,124,000		(7,729,000)
Deferred tax assets and liabilities, net	7,160,000		3,515,000
Other assets, current and non-current portion	16,950,000		(568,000)
Accounts payable and accrued expenses	14,869,000		158,446,000
Billings in excess of costs and earnings	8,046,000		(9,942,000)
Other liabilities, current and non-current portion	(3,468,000)		12,744,000
Net cash provided by (used in) operating activities	14,567,000		(4,244,000)
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net, including contingent consideration	(133,392,000)		(15,862,000)
Capital expenditures	(71,382,000)		(28,490,000)
Proceeds from sale of property and equipment	18,978,000		3,808,000
Proceeds from sale or redemption of investments	5,025,000		0
Proceeds from disposal of business, net	0		97,728,000
Investments in life insurance policies	(94,000)		(284,000)
Net cash (used in) provided by investing activities	(180,865,000)		56,900,000
Cash flows provided by (used in) financing activities:
Proceeds from issuance of 4.875% senior notes	400,000,000		0
Repayment of 7.625% senior notes	(150,000,000)		0
Proceeds from credit facility	499,666,000		422,550,000
Repayments of credit facility	(558,596,000)		(418,750,000)
Repayments of other borrowings	(18,570,000)		(10,542,000)
Proceeds from (repayment of) book overdrafts	7,989,000		(5,290,000)
Payments of capital lease obligations	(21,139,000)		(9,668,000)
Proceeds from stock option exercises and other share-based awards	4,283,000		766,000
Excess tax benefit from stock-based compensation	1,462,000		70,000
Purchases of treasury stock	0		(35,087,000)
Payments for debt extinguishment, call premiums	(4,116,000)		0
Payments of financing costs	(7,569,000)		(115,000)
Net cash provided by (used in) financing activities	153,410,000		(56,066,000)
Net decrease in cash and cash equivalents	(12,888,000)		(3,410,000)
Net effect of currency translation on cash	(274,000)		(56,000)
Cash and cash equivalents - beginning of period	26,767,000		20,280,000
Cash and cash equivalents - end of period	13,605,000		16,814,000
Cash and cash equivalents of discontinued operations	310,000		386,000
Cash and cash equivalents of continuing operations	13,295,000		16,428,000
Supplemental cash flow information:
Interest paid	17,756,000		13,726,000
Income taxes paid, net of refunds	41,625,000		18,896,000
Supplemental disclosure of non-cash investing and financing information:
Equipment acquired under capital lease	56,622,000		26,729,000
Machinery and Equipment [Member]
Supplemental disclosure of non-cash investing and financing information:
Equipment acquired under financing arrangements	23,406,000		2,204,000
Inventories [Member]
Supplemental cash flow information:
Non-cash transaction, value of consideration received	0		12,005,000
Contracts Accounted for under Percentage of Completion [Member]
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for losses on construction projects, net	1,387,000		(9,894,000)
Common Stock Outstanding [Member]
Supplemental disclosure of non-cash investing and financing information:
Value of shares withheld for payroll taxes under share-based compensation arrangements	1,463,000		0
Investor [Member] | Common Stock Outstanding [Member]
Supplemental cash flow information:
Non-cash transaction, value of consideration received	$ 6,002,000		$ 0

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