Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Reduction in net deferred tax assets to reflect new statutory rate		$ 8,900,000
Tax credit carryforwards		$ 3,000,000
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		61,600,000
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		$ 4,400,000
Expired state net operating losses		$ 1,200,000
Operating loss carryforwards expiration period		2026
US [Member]
Operating Loss Carryforwards [Line Items]
US federal corporate tax rate		35.00%
Scenario, Forecast [Member]
Operating Loss Carryforwards [Line Items]
Global intangible low tax income, effective tax rate	10.50%
Scenario, Forecast [Member] | US [Member]
Operating Loss Carryforwards [Line Items]
US federal corporate tax rate	21.00%