Acquisitions (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended				3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 29, 2012		Oct. 01, 2011		Sep. 29, 2012 Acquisitions		Oct. 01, 2011 Acquisitions		Oct. 01, 2011 Acquisitions 2011 and 2012 [Member]	Oct. 01, 2011 Acquisitions 2011 and 2012 [Member]	Mar. 01, 2011 RFPD [Member]	Dec. 31, 2011 Nu Horizons [Member]	Oct. 01, 2011 Nu Horizons [Member]	Jan. 03, 2011 Nu Horizons [Member]	Sep. 29, 2012 Series of Individually Immaterial Business Acquisitions [Member]	Dec. 31, 2011 Series of Individually Immaterial Business Acquisitions [Member]	Sep. 29, 2012 Individual Immaterial Business Acquisition [Member]
Business Acquisition [Line Items]
Number of Businesses Acquired					7		6
Business Acquisition, Purchase Price Allocation [Abstract]
Business Acquisition, Cost of Acquired Entity, Purchase Price											$ 235,973			$ 161,125	$ 327,020	$ 175,892	$ 90,576
Business Acquisition, Purchase Price Allocation, Current Assets, Cash and Cash Equivalents														18,085	37,330	22,337
Business Acquisition, Purchase Price Allocation, Debt Paid														26,375	28,861
Business Acquisition, Contingent Consideration, at Fair Value															10,390
Sales	4,962,331		5,186,857		15,002,423		15,949,791
Net income attributable to shareholders	103,617		132,216		331,628		424,722
Basic	$ 0.96		$ 1.17		$ 3.01		$ 3.70
Diluted	$ 0.94	[1]	$ 1.15	[1]	$ 2.96	[1]	$ 3.64	[1]
Business Combination, Pro Forma Information [Abstract]
Business Acquisition, Pro Forma Revenue									5,334,078	16,533,556
Business Acquisition, Pro Forma Net Income (Loss)									134,332	437,448
Business Acquisition, Pro Forma Earnings Per Share, Basic									$ 1.18	$ 3.81
Business Acquisition, Pro Forma Earnings Per Share, Diluted									$ 1.17	$ 3.75
Gain on bargain purchase	0		0		0		1,755					(667)	1,755
Gain on bargain purchase, net of taxes												(410)	1,078
Gain on Purchase of Business, Per Share Basic													$ 0.01
Gain on Purchase of Business, Per Share Diluted													$ 0.01
Payments to acquire additional interest in majority-owned subsidiary					$ 2,526

[1] (a)Stock-based compensation awards for the issuance of 1,789 and 1,403 shares for the third quarter and first nine months of 2012 and 1,815 and 1,017 shares for the third quarter and first nine months of 2011, respectively, were excluded from the computation of net income per share on a diluted basis as their effect was anti-dilutive.