Supplemental Guarantor Information (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Cash Flow Statements [Abstract]
Net cash provided by operating activities	$ 184,563	$ 111,549	$ 151,810
Cash flows from investing activities:
Cash used to acquire businesses, net of cash acquired	(60,519)	(119,110)	(20,703)
Capital expenditures	(40,053)	(28,194)	(40,377)
Proceeds from disposal of businesses and tangible assets	1,213	138,952	2,031
Net cash used for investing activities	(99,359)	(8,352)	(59,049)
Cash flows from financing activities:
Payments under share repurchase program	(50,000)
Borrowings under credit arrangements			193,732
Payments under borrowing arrangements		(46,268)	(193,732)
Cash dividends paid	(9,410)	(9,412)	(9,373)
Debt issuance costs	(3,296)		(11,810)
Tax benefit (deficiency) related to share-based compensation	1,790	(110)	(1,564)
Proceeds from exercise of stock options	4,599	3,158	699
Cash received upon termination of derivative instruments		4,217
Net cash used for financing activities	(56,317)	(48,415)	(22,048)
Effect of currency exchange rate changes on cash and cash equivalents	(4,824)	(5,008)	10,753
Increase in cash and cash equivalents	24,063	49,774	81,466
Cash and cash equivalents, beginning of period	358,653	308,879	227,413
Cash and cash equivalents, end of period	382,716	358,653	308,879
Issuer [Member]
Consolidated Cash Flow Statements [Abstract]
Net cash provided by operating activities	60,648	109,850	63,176
Cash flows from investing activities:
Cash used to acquire businesses, net of cash acquired	(60,519)	(119,110)	(20,110)
Capital expenditures	(26,061)	(16,056)	(20,725)
Proceeds from disposal of businesses and tangible assets	1,136	138,934	910
Net cash used for investing activities	(85,444)	3,768	(39,925)
Cash flows from financing activities:
Payments under share repurchase program	(50,000)
Borrowings under credit arrangements			193,732
Payments under borrowing arrangements		(46,268)	(193,732)
Cash dividends paid	(9,410)	(9,412)	(9,373)
Debt issuance costs	(3,296)		(11,810)
Tax benefit (deficiency) related to share-based compensation	1,790	(110)	(1,564)
Proceeds from exercise of stock options	4,599	3,158	699
Intercompany capital contributions and dividends		49,641
Cash received upon termination of derivative instruments		4,217
Net cash used for financing activities	(56,317)	1,226	(22,048)
Increase in cash and cash equivalents	(81,113)	114,844	1,203
Cash and cash equivalents, beginning of period	173,699	58,855	57,652
Cash and cash equivalents, end of period	92,586	173,699	58,855
Non-Guarantor Subsidiaries [Member]
Consolidated Cash Flow Statements [Abstract]
Net cash provided by operating activities	123,915	1,699	88,634
Cash flows from investing activities:
Cash used to acquire businesses, net of cash acquired			(593)
Capital expenditures	(13,992)	(12,138)	(19,652)
Proceeds from disposal of businesses and tangible assets	77	18	1,121
Net cash used for investing activities	(13,915)	(12,120)	(19,124)
Cash flows from financing activities:
Intercompany capital contributions and dividends		(49,641)
Net cash used for financing activities		(49,641)
Effect of currency exchange rate changes on cash and cash equivalents	(4,824)	(5,008)	10,753
Increase in cash and cash equivalents	105,176	(65,070)	80,263
Cash and cash equivalents, beginning of period	184,954	250,024	169,761
Cash and cash equivalents, end of period	$ 290,130	$ 184,954	$ 250,024