Condensed Unaudited Consolidated Statements Of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net income	$ 71,076,000	$ 97,411,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	65,767,000	53,552,000
Stock-based compensation expense	3,351,000	2,779,000
Excess tax benefit from stock-based compensation	(302,000)	(3,942,000)
Non-cash interest expense	6,424,000	5,460,000
Provision for doubtful accounts	2,533,000	1,478,000
Impairment of securities available for sale	0	457,000
(Gain) loss on sale of assets	(1,569,000)	139,000
Impairment charges and loss on disposal of businesses	12,922,000	0
Gain on remeasurement of equity interest in acquiree	0	(29,041,000)
Changes in assets and liabilities, net of assets acquired and liabilities assumed:
Accounts receivable	(233,220,000)	(226,993,000)
Inventories	9,936,000	(35,340,000)
Deferred tax assets and liabilities, net	(3,555,000)	38,816,000
Other assets, current and non-current portion	(6,383,000)	939,000
Accounts payable and accrued expenses	176,289,000	93,467,000
Billings in excess of costs and earnings	(3,367,000)	(61,916,000)
Other liabilities, current and non-current portion	14,768,000	(361,000)
Net cash provided by (used in) operating activities	114,670,000	(63,095,000)
Cash flows provided by (used in) investing activities:
Cash paid for acquisitions, net, including contingent consideration	(17,496,000)	(85,367,000)
Capital expenditures	(50,331,000)	(56,996,000)
Proceeds from sale of assets	5,808,000	4,456,000
Proceeds from disposal of business, net	97,728,000	0
Proceeds from redemption of investments	0	4,600,000
Investments in life insurance policies	(284,000)	(283,000)
Net cash provided by (used in) investing activities	35,425,000	(133,590,000)
Cash flows (used in) provided by financing activities:
Proceeds from credit facility	631,815,000	135,761,000
Repayments of credit facility	(681,815,000)	(108,761,000)
Repayments of other borrowings	(15,510,000)	(9,098,000)
Proceeds from (repayments of) book overdrafts	(5,645,000)	22,698,000
Payments of capital lease obligations	(14,806,000)	(12,926,000)
Proceeds from stock option exercises and other share-based awards	1,445,000	11,921,000
Excess tax benefit from stock-based compensation	302,000	3,942,000
Purchases of treasury stock	(75,000,000)	(1,950,000)
Payments of financing costs	(113,000)	(6,069,000)
Net cash (used in) provided by financing activities	(159,327,000)	35,518,000
Net decrease and cash equivalents	(9,232,000)	(161,167,000)
Net effect of currency translation on cash	135,000	(74,000)
Cash and cash equivalents - beginning of period	20,279,000	177,604,000
Cash and cash equivalents - end of period	11,182,000	16,363,000
Cash and cash equivalents of discontinued operations	710,000	9,079,000
Cash and cash equivalents of continuing operations	10,472,000	7,284,000
Supplemental cash flow information:
Interest paid	20,879,000	20,558,000
Income taxes paid, net of refunds	37,219,000	18,570,000
Supplemental disclosure of noncash information:
Equipment acquired under capital lease	29,917,000	5,286,000
Inventories [Member]
Supplemental cash flow information:
Receipt of inventory prepaid in prior year	12,005,000	0
Machinery and Equipment [Member]
Supplemental disclosure of noncash information:
Equipment acquired under financing arrangements	4,887,000	10,692,000
Conversion of leases from operating to capital	0	23,366,000
Equity Issued in Business Combination [Member]
Supplemental disclosure of noncash information:
Shares issued in connection with business combinations	0	94,213,000
Convertible Debt [Member]
Supplemental disclosure of noncash information:
Exchange of senior convertible notes	$ 0	$ 202,322,000