Receivables - Schedule of Finance and Notes Receivable Aging and Accrual Status (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Finance Receivable
Accounts Notes And Loans Receivable [Line Items]
Receivables on nonaccrual status	$ 0.2	$ 2.3
Receivables past due 90 days or more and still accruing	0.0	0.0
Receivables subject to general reserves	16.3	10.8
Allowance for doubtful accounts	(0.4)	(0.2)
Receivables subject to specific reserves	2.5	2.3
Allowance for doubtful accounts	(2.3)	(2.0)
Notes Receivable
Accounts Notes And Loans Receivable [Line Items]
Receivables on nonaccrual status	0.0	0.0
Receivables past due 90 days or more and still accruing	0.0	0.0
Receivables subject to general reserves	0.0	0.0
Allowance for doubtful accounts	0.0	0.0
Receivables subject to specific reserves	0.0	0.4
Allowance for doubtful accounts	$ 0.0	$ (0.4)