Acquisitions (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended				3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2012		Jul. 02, 2011		Jun. 30, 2012		Jul. 02, 2011		Jul. 02, 2011 Acquisitions 2011 and 2012 [Member]	Jul. 02, 2011 Acquisitions 2011 and 2012 [Member]	Mar. 01, 2011 RFPD [Member]	Dec. 31, 2011 Nu Horizons [Member]	Jul. 02, 2011 Nu Horizons [Member]	Jan. 03, 2011 Nu Horizons [Member]	Jun. 30, 2012 Series of Individually Immaterial Business Acquisitions [Member]	Dec. 31, 2011 Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition, Purchase Price Allocation [Abstract]
Business Acquisition, Cost of Acquired Entity, Purchase Price											$ 235,973			$ 161,125	$ 232,161	$ 175,892
Business Acquisition, Purchase Price Allocation, Current Assets, Cash and Cash Equivalents														18,085	37,100	22,337
Business Acquisition, Purchase Price Allocation, Debt Paid														26,375	28,861
Business Acquisition, Contingent Consideration, at Fair Value															10,390
Sales	5,150,563		5,539,931		10,040,092		10,762,934
Net income attributable to shareholders	114,383		156,197		228,011		292,506
Basic	$ 1.04		$ 1.35		$ 2.05		$ 2.54
Diluted	$ 1.02	[1]	$ 1.33	[1]	$ 2.02	[1]	$ 2.49	[1]
Business Combination, Pro Forma Information [Abstract]
Business Acquisition, Pro Forma Revenue									5,690,257	11,164,868
Business Acquisition, Pro Forma Net Income (Loss)									158,842	302,518
Business Acquisition, Pro Forma Earnings Per Share, Basic									$ 1.38	$ 2.62
Business Acquisition, Pro Forma Earnings Per Share, Diluted									$ 1.35	$ 2.58
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 1,552 and 804 shares for the second quarter and first six months of 2012 and 398 and 342 shares for the second quarter and first six months of 2011, respectively, were excluded from the computation of net income per share on a diluted basis as their effect was anti-dilutive.