Property and Equipment, Net - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Construction in progress and facility lease obligation	$ 220,600,000		$ 220,600,000		$ 196,000,000
Depreciation and amortization expense	$ 951,000	$ 1,300,000	$ 2,700,000	$ 3,900,000