Income Taxes -Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Effective income tax rate	22.70%	19.50%	21.00%	16.70%
Unrecognized tax benefits, uncertain tax positions	$ 14.0		$ 14.0		$ 10.9
Unrecognized tax benefits, accrued interest	$ 0.7		$ 0.7		$ 0.4