Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 15,438	$ 23,002
Americas [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	2,879	4,744
Asia Pacific [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	6,860	8,026
Europe [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 5,699	$ 10,232