Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Deferred tax assets, valuation allowance	$ 44,440,000	$ 28,448,000
Deferred tax assets, valuation allowance, change in amount	16,000,000	14,800,000
Unrecognized deferred tax assets related to stock compensation	2,291,000	1,042,000
Deferred tax assets, federal operating loss carry forwards	97,600,000
Deferred tax assets, state operating loss carry forwards	$ 53,700,000
Operating loss carry forwards, expiry year start	2021
Operating loss carry forwards, expiry year end	2036
Deferred tax credit carry forwards	$ 2,600,000
Deferred tax credit carry forwards, year begin to expiration	2031
Unrecognized tax benefits, accrued interest and penalties	$ 0	$ 0
Accounting Standards Codification 718 [Member]
Income Tax Disclosure [Abstract]
Unrecognized deferred tax assets related to stock compensation	$ 200,000