Goodwill, In-Process Research and Development and Intellectual Property - Summary of Gross Intellectual Property, Accumulated Amortization, and Net Intellectual Property (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 66,413	$ 66,413
Accumulated Amortization	(27,936)	(19,724)
Foreign currency translation impact	4,074	5,529
Net Carrying Amount	42,551	52,218
Technology and Patents Purchased [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	400	400
Accumulated Amortization	(62)	(30)
Foreign currency translation impact	36	50
Net Carrying Amount	374	420
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	66,813	66,813
Accumulated Amortization	(27,998)	(19,754)
Foreign currency translation impact	4,110	5,579
Net Carrying Amount	$ 42,925	$ 52,638