Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax provision at statutory U.S. rate	$ 8,554	$ 12,232	$ 13,753
Increase (decrease) in tax provision resulting from:
State and local taxes, net	(553)	(554)	(580)
Foreign tax rate differential	(3,244)	(5,762)	(7,150)
Nondeductible items	839	874	1,093
Federal research and development credits	(710)	(678)	(842)
Change in deductibility of social insurance	8	649	688
Valuation allowance	1,598	621	661
Foreign permanent benefit	(2,110)	(675)	0
Other	422	95	294
Total provision for income taxes	$ 4,804	$ 6,802	$ 7,917