Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Deferred tax asset valuation allowance	$ 24,911,000	$ 24,552,000
Tax credit carryforwards	$ 2,800,000
Tax credit carryforwards expiration period	2018
Period of increase in ownership	3 years
Unrealized tax benefits	$ 0	$ 0
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	55,700,000
Domestic Tax Authority [Member] | Expire in 2022 and 2023 [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	$ 36,300,000
Domestic Tax Authority [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration period	2022
Domestic Tax Authority [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration period	2023
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	$ 1,800,000
Expired state net operating losses	$ 200,000
Operating loss carryforwards expiration period	2017