Income Taxes (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax rate high tax exception benefit	$ 2.0
Income tax benefit	0.7	$ 0.5	$ 0.8
Unrecognized tax benefits	1.0	1.0
Accrued unrecognized tax benefits interest and penalties	$ 0.4	$ 0.4