Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	$ 70,736	$ 90,516	$ 210,815	$ 277,624
United States
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	28,865	37,166	86,401	108,174
EMEA
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	20,648	26,424	61,058	87,554
Other APAC
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	11,463	16,120	37,532	46,550
China
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	7,758	7,751	19,991	25,007
Other Americas
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	2,002	3,055	5,833	10,339
Product sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	48,082	66,788	146,866	209,411
Product sales | Transferred at Point in Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	44,561	63,806	137,324	200,982
Product sales | Transferred over Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	3,521	2,982	9,542	8,429
Service sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	22,654	23,728	63,949	68,213
Service sales | Transferred at Point in Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	9,623	12,361	27,268	35,650
Service sales | Transferred over Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	$ 13,031	$ 11,367	$ 36,681	$ 32,563