Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Income tax operating loss carryforwards	$ 85.5
Income tax operating loss carryforwards not expired	31.6
Operating loss carryforwards expiration, 2019	0.0
Operating loss carryforwards Expiration, 2020	0.0
Operating loss carryforwards expiration, 2032 and beyond	$ 41.9
Federal income tax rates	21.00%	34.00%	34.00%
Minimum [Member]
Income Taxes [Line Items]
Income tax examination year under examination	P3Y
Maximum [Member]
Income Taxes [Line Items]
Income tax examination year under examination	P5Y
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Income tax operating loss carryforwards	$ 12.0
State carryforward period	20 years
Federal and state [Member]
Income Taxes [Line Items]
Income tax operating loss carryforwards	$ 73.5