Receivables - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accounts Notes And Loans Receivable [Line Items]
Allowance for doubtful accounts at beginning of year	$ 11.3	$ 9.9
Provision for doubtful accounts, net of recoveries	(0.6)	1.8
Charge-off of accounts	(1.1)	(0.4)
Allowance for doubtful accounts at end of year	9.6	11.3
Finance Receivable
Accounts Notes And Loans Receivable [Line Items]
Allowance for doubtful accounts at beginning of year	2.2	2.8
Provision for doubtful accounts, net of recoveries	0.5	(0.6)
Allowance for doubtful accounts at end of year	2.7	2.2
Notes Receivable
Accounts Notes And Loans Receivable [Line Items]
Allowance for doubtful accounts at beginning of year	0.4
Provision for doubtful accounts, net of recoveries		0.4
Charge-off of accounts	(0.4)
Allowance for doubtful accounts at end of year		0.4
Trade and Other Receivable
Accounts Notes And Loans Receivable [Line Items]
Allowance for doubtful accounts at beginning of year	8.7	7.1
Provision for doubtful accounts, net of recoveries	(1.1)	2.0
Charge-off of accounts	(0.7)	(0.4)
Allowance for doubtful accounts at end of year	$ 6.9	$ 8.7