Supplemental Financial Information - Disaggregation of Sales by Timing of Revenue Recognized and Revenue by Category (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Net revenues	$ 376.2	$ 317.4	$ 1,053.5	$ 900.7
Suspended Operations
Disaggregation of Revenue [Line Items]
Net revenues		(1.2)	(0.2)	(11.4)
Oil Change And Related Fees
Disaggregation of Revenue [Line Items]
Net revenues	280.7	235.7	782.8	660.9
Non-oil Change And Related Fees
Disaggregation of Revenue [Line Items]
Net revenues	77.2	65.3	219.9	182.8
Franchise Fees And Other
Disaggregation of Revenue [Line Items]
Net revenues	18.3	16.4	50.8	57.0
Net revenues transferred at a point in time
Disaggregation of Revenue [Line Items]
Net revenues	358.3	301.7	1,003.4	857.2
Franchised revenues transferred over time
Disaggregation of Revenue [Line Items]
Net revenues	$ 17.9	$ 15.7	$ 50.1	$ 43.5