Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Valuation allowance		$ 58,248,000	$ 71,023,000
Corporate federal tax rate		34.00%	34.00%
Net deferred tax asset		$ 1,895,000	$ 3,711,000
Net recognized deferred tax asset		0
Decrease in net deferred assets		15,800,000
Decrease of valuation allowance		$ 15,800,000
Net operating losses, carried back term		2 years
Net operating losses, carried forward term		20 years
Maximum offset percentage of indefinite carryforward operating loss		80.00%
Repatriation tax		$ 0
Operating loss carryforwards, expiration end year		2037
Liabilities for unrecognized tax benefits		$ 2,800,000	2,800,000
Amount of unrecognized tax benefits, which, if recognized, would affect the tax rate		100,000	100,000
Penalties accrued related to unrecognized tax benefits		2,000	1,000
Interest accrued related to unrecognized tax benefits		4,000	4,000
Recognized total liability for penalties		13,000	14,000
Recognized total liability for interest		28,000	$ 32,000
Federal
Income Taxes [Line Items]
Operating loss carryforwards		108,500,000
State
Income Taxes [Line Items]
Operating loss carryforwards		34,500,000
Foreign
Income Taxes [Line Items]
Operating loss carryforwards		$ 125,700,000
Maximum
Income Taxes [Line Items]
Corporate federal tax rate		35.00%
Scenario, Plan
Income Taxes [Line Items]
Corporate federal tax rate	21.00%