Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Deferred tax assets:
Share-based compensation	$ 4.8	$ 1.7
Deferred compensation	5.1	4.7
Net operating loss carryforwards	18.7	17.7
Intangible assets	6.4	6.5
Bad debt reserve	7.8	7.3
Hedging	17.0	0.0
Foreign tax credit carryforwards	1.6	2.0
Other compensation	8.0	7.0
Property and equipment	0.0	6.3
Pension	2.1	1.2
Right of use assets	23.8	22.9
Other	2.0	1.8
Total gross deferred tax assets	97.3	79.1
Less valuation allowance	(15.8)	(15.0)
Deferred tax assets	81.5	64.1
Deferred income tax liabilities:
Unrealized gain on securities	2.5	2.8
Prepaid expenses	3.8	4.2
Property and equipment	2.0	0.0
Right of use liabilities	20.8	21.6
Other deferred liabilities	0.4	0.4
Deferred income tax liabilities	29.5	29.0
Deferred income taxes, net	$ 52.0	$ 35.1