Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Line Items]
Income tax benefit	$ 0	$ 0	$ 0
Federal [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 65,401,000
Net operating loss carry forwards, expiration year, start	2031
Research and development tax credit carryforwards, expiration year, start		2031
Federal [Member] | Research and Development Tax Credit [Member]
Income Tax Disclosure [Line Items]
Research and development tax credit carryforwards		$ 3,045,000
State [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 64,266,000
Net operating loss carry forwards, expiration year, start	2031
Research and development tax credit carryforwards, expiration year, start		2027
State [Member] | Research and Development Tax Credit [Member]
Income Tax Disclosure [Line Items]
Research and development tax credit carryforwards		$ 1,331,000
Stock Based Compensation Tax Benefit | Federal [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 856,000
Stock Based Compensation Tax Benefit | State [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 856,000