Income Taxes - Income Tax Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax provision at statutory U.S. rate	$ 9,872	$ 8,377	$ 8,578
Increase (decrease) in tax provision resulting from:
State and local taxes, net	(397)	(246)	(262)
Foreign tax rate differential	(3,804)	(3,488)	(3,528)
Nondeductible items	989	388	407
Federal research and development credits	(1,149)	(369)	(503)
Change in deductibility of social insurance	214	617	0
Valuation allowance	520	2,592	0
Other	(172)	214	593
Total provision for income taxes	$ 6,073	$ 8,085	$ 5,285