Goodwill, In-Process Research and Development and Intellectual Property - Carrying Value of Goodwill and Change in Balance (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance			$ 68,697,000	$ 130,869,000
Foreign currency translation impact			2,671,000	(388,000)
Impairment loss	$ 0	$ (61,784,000)	0	(61,784,000)	$ 0
Ending balance			$ 71,368,000	$ 68,697,000	$ 130,869,000