Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Asset [Line Items]
Federal statutory rate		34.00%	34.00%	34.00%
Decrease of net deferred tax assets		$ 7,200,000
Income Tax Disclosure [Abstract]
Deferred tax assets, valuation allowance		15,395,000	$ 44,440,000
Deferred tax assets, valuation allowance, change in amount		(29,000,000)	16,000,000
Deferred tax assets, federal operating loss carry forwards		$ 31,400,000
Federal operating loss carry forwards, expiry year		2037
Deferred tax assets, state operating loss carry forwards		$ 54,000,000
Operating loss carry forwards, expiry year start		2022
Operating loss carry forwards, expiry year end		2037
Deferred tax credit carry forwards		$ 400,000
Deferred tax credit carry forwards, year begin to expiration		2032
Unrecognized tax benefits, accrued interest and penalties		$ 0	$ 0
Scenario, Forecast [Member]
Deferred Tax Asset [Line Items]
Federal statutory rate	21.00%