Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Accrual on interest and penalties related to income taxes	$ 0	$ 0
Net operating loss carryforwards	$ 17,400,000
Cumulative change in ownership for limitation of use of net operating loss and research and development credit carryforwards	50.00%
Period of cumulative change of ownership	3 years
Research and development credit	$ 2,100,000
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	$ 43,900,000
Expiry date of carry forwards	Dec. 31, 2027
Tax credit carry forwards	$ 1,500,000
California [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	$ 42,900,000
Expiry date of carry forwards	Dec. 31, 2017
Tax credit carry forwards	$ 1,000,000
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax years subject to examination by taxing authorities	2007