Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Tax Credit Carryforward [Line Items]
Income tax benefits	$ 0	$ 0
Net operating loss carryforwards for federal income tax purposes	16,500,000
Net operating loss carryforwards for State income tax purposes	13,000,000
Research and development tax credit carryforwards for federal and state income tax purposes	1,008,000	889,000
Deferred tax assets, Gross	33,272,000	24,402,000
Unrecognized tax benefits	0	0
Domestic Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards for federal and state income tax, expiration period	2024
Research and development tax credit carryforwards for federal and state income tax purposes	809,000
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Research and development tax credit carryforwards for federal and state income tax purposes, expiration period	2025
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards for federal and state income tax, expiration period	2030
Research and development tax credit carryforwards for federal and state income tax purposes	$ 302,000
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Research and development tax credit carryforwards for federal and state income tax purposes, expiration period	2023