Income Taxes - Addtional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax [Line Items]
Operating Loss Carryforwards	$ 27,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	1,259	$ 877
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ 3,001	$ 1,899	$ 1,530
Research And Development Tax Credit Carryforward, Expiration Period	2028 years
Research and Development Expense [Member]
Income Tax [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 1,300
Minimum [Member]
Income Tax [Line Items]
Operating Loss Carry forwards Expiration Period	2026