Commitments and Contingencies (Detail) $ in Millions	1 Months Ended			12 Months Ended
	Jul. 31, 2015 USD ($) ft²	Nov. 30, 2012 USD ($) ft²	Jul. 31, 2010 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Aug. 31, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Tenant incentive	$ 8.5						$ 1.4
Area of rented space (in square feet) | ft²	59,000	7,500
Additional tenant improvement allowance		$ 0.7
Tenant improvement allowance, interest rate		8.00%
Minimum period for early termination, in months			60 months
Mimimum notice for early termination, in months			9 months
Rent expense				$ 0.6	$ 0.7	$ 0.7
Deferred rent				0.4	0.7
Tenant incentive obligation balance				0.3	$ 0.6
Lease term, in months	96 months
Amount of incentive used				0.1
Tenant improvement allowance used				$ 1.7
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Tenant incentive			$ 0.1
Additional Leasehold Improvements
Property, Plant and Equipment [Line Items]
Tenant incentive			$ 0.6