Goodwill, In-Process Research and Development and Intellectual Property - Carrying Value of Company's IPR&D Assets and Change in Balance (Detail) - In-Process Research and Development [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Beginning balance	$ 15,920	$ 16,511
Foreign currency translation impact	1,993	(591)
Transfer to developed technology	$ (17,913)
Ending balance		$ 15,920