Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Income Tax Disclosure [Line Items]
Effective tax rate	9.60%	25.80%	7.20%	26.50%
Income tax rate at federal statutory rates	21.00%	21.00%	21.00%	21.00%
Federal Tax [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	$ 7.0		$ 7.0
Charitable Institution [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	1.0		1.0
State Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	$ 7.8		$ 7.8		$ 5.2