Commitments and Contingencies (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($) ft²	Dec. 31, 2017 USD ($) ft² lease_arrangement	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Damages sought | $	$ 920
Number Of Lease Arrangements | lease_arrangement		7
Operating lease rent expense | $		$ 902	$ 1,006	$ 1,166
Equipment Construction Contracts | Performance Guarantee
Other commitment | $	$ 3,250	$ 3,250
Gallarate, Italy | Office Building
Area of property (in square feet)	1,636	1,636
Westlake, Ohio | Office Building
Area of property (in square feet)	3,000	3,000
Aurora Illinois | Office Building
Area of property (in square feet)	11,000	11,000
Durham, North Carolina | Office Building
Area of property (in square feet)	2,590	2,590
Beijing, China | Office Building
Area of property (in square feet)	9,000	9,000
Stamford, Connecticut | Office Building
Area of property (in square feet)	6,440	6,440
Overland Park | Office Building
Area of property (in square feet)	600	600