Commitments and Contingencies - Additional Information (Detail) - Menlo Park, California [Member] $ in Millions	1 Months Ended		3 Months Ended
	Dec. 31, 2015 ft²	Mar. 31, 2014 ft²	Mar. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Operating facility lease area | ft²		12,943
Operating facility lease term		39 months
Total obligation under lease | $			$ 1.0
Sublease Agreement [Member]
Loss Contingencies [Line Items]
Operating facility lease area | ft²	10,891
Operating facility lease term	24 months
Total obligation under lease | $			$ 1.1
Lease commencement date			Jan. 01, 2016