Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Income Tax [Line Items]
Total income tax expense	$ 10,000	$ 26,000
Decrease in net valuation allowance	$ (3,200,000)	$ 14,300,000
Corporate tax rate	21.00%	34.00%
Operating loss carryforwards limitations on use	it has not forfeited the right to carryforward tax losses up to 20 years
Tax years subject to examination to extent of NOLs being carried forward	2000
Uncertain Tax Position	$ 0
Federal [Member]
Schedule Of Income Tax [Line Items]
Aggregate amount of net operating loss	168,600,000
Operating loss carryforward generated	168,600,000
Operating loss carryforward unutilized	7,200,000
State [Member]
Schedule Of Income Tax [Line Items]
Aggregate amount of net operating loss	$ 123,200,000
Maximum [Member]
Schedule Of Income Tax [Line Items]
Corporate tax rate		35.00%
Right to carryforward tax losses, period	20 years
Tax year subject to examination by the tax authorities	2018
Minimum [Member]
Schedule Of Income Tax [Line Items]
Tax year subject to examination by the tax authorities	2000