Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Effective tax rate	8.00%	6.20%
Income tax rate at federal statutory rates	21.00%	21.00%
Federal Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	$ 2.5	$ 2.5	$ 39.5
State Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	10.2	10.2	15.0
Federal Tax Credits [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	3.1	3.1	7.1
Charitable Contribution [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	$ 4.5	$ 4.5	$ 4.0