Income Taxes - Summary of Significant Components of Deferred Tax Assets (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Components Of Deferred Tax Assets [Abstract]
Acquired technology	$ 103,000	$ 201,000
Stock compensation expense	490,000	539,000
Accruals and other	216,000	130,000
Total deferred tax assets	809,000	870,000
Less valuation allowance	$ (809,000)	$ (870,000)