Income Taxes - A reconciliation of the beginning and ending gross unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 4,618	$ 5,274	$ 5,752
Additions (reductions) based on prior year tax positions	(2,156)	197	0
Reductions related to settlements with taxing authorities	(1,783)	0	0
Reductions as a result of a lapse of statute of limitations	(449)	0	0
Foreign currency translation	263	(853)	(478)
Balance at end of year	$ 493	$ 4,618	$ 5,274