Income Taxes -Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Effective income tax rate	24.50%	18.40%	19.90%	20.60%
Unrecognized tax benefits, uncertain tax positions	$ 17.1		$ 17.1		$ 13.8
Unrecognized tax benefits, accrued interest	$ 1.7		$ 1.7		$ 0.9