Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) ft² lease_arrangement	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Number Of Lease Arrangements | lease_arrangement	7
Operating lease rent expense | $	$ 745	$ 902	$ 1,006
Equipment Construction Contracts | Performance Guarantee
Other commitment | $	$ 5,028
Gallarate, Italy | Office Building
Area of property (in square feet)	1,636
Westlake, Ohio | Office Building
Area of property (in square feet)	3,000
Aurora Illinois | Office Building
Area of property (in square feet)	11,000
Durham, North Carolina | Office Building
Area of property (in square feet)	2,590
Beijing, China | Office Building
Area of property (in square feet)	9,000
Stamford, Connecticut | Office Building
Area of property (in square feet)	6,440
Overland Park | Office Building
Area of property (in square feet)	600