Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning of year	$ 5,104	$ 1,957	$ 1,294
Charges to costs and expenses	1,699	1,010	1,056
Write-offs of uncollectible accounts, net of recoveries	(973)	(92)	(497)
Business acquisitions and disposals	(148)	2,330	12
Currency translation adjustments	(126)	(101)	92
Allowance for doubtful accounts, end of year	$ 5,555	$ 5,104	$ 1,957