Goodwill and Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at January 1	$ 33,872	$ 31,343
Foreign currency translation adjustment	(1,659)	2,529
Balance at December 31	$ 32,213	$ 33,872