Balance Sheet Components - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Balance Sheet Components [Abstract]
Depreciation expense	$ 1,468,000	$ 1,445,000	$ 1,995,000
Outstanding obligations related to construction-in-progress	200,000	0
Capitalized interest costs	113,000	0	$ 0
Fill/Finish Line
Impaired Long-Lived Assets Held and Used [Line Items]
Loss on impairment of long-lived assets	2,900,000	9,100,000
Remaining book value of impaired long-lived assets	2,400,000	5,100,000
Other Assets
Impaired Long-Lived Assets Held and Used [Line Items]
Remaining book value of impaired long-lived assets	$ 100,000	$ 200,000