Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning of year	$ 5,556	$ 5,104	$ 1,957
Charges to costs and expenses	2,383	1,699	1,010
Write-offs of uncollectible accounts, net of recoveries	(1,055)	(973)	(92)
Business acquisitions and disposals	(351)	(148)	2,330
Currency translation adjustments	41	(126)	(101)
Allowance for doubtful accounts, end of year	$ 6,574	$ 5,556	$ 5,104