Summary of Significant Accounting Policies - Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 1,062	$ 1,117	$ 708
Charged to expense	40	42	580
Deductions	(38)	(91)	(165)
Effect of foreign currency exchange rates	(4)	(6)	(6)
Balance at end of period	$ 1,060	$ 1,062	$ 1,117