Goodwill and Intangible Assets, Net, Carrying Amount of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Goodwill
Balance at the beginning of the period			$ 137,140
Reclassifications			0
Foreign exchange			(681)
Balance at the end of the period	$ 136,459	$ 137,313	136,459	$ 137,313
Intangible Assets
Balance at the beginning of the period			29,326
Reclassifications			220
Amortization	(1,400)	(1,500)	(3,981)	(4,700)
Foreign exchange			(108)
Balance at the end of the period	$ 25,457	$ 30,050	$ 25,457	$ 30,050