Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 16.8	$ 10.8	$ (24.1)	$ (1.3)
Net derivative gains and other costs arising during the period, net of tax expense of $5.8; $0.5; $6.2; and $1.5, respectively	[1]	16.0	1.1	17.2	3.9
Reclassification of (gains) losses into net income (loss), net of tax (expense) of $(0.5); $0.0; $(1.5); and $0.0, respectively		(2.1)	0.1	(5.4)	0.2
Other comprehensive income		13.9	1.2	11.8	4.1
Comprehensive income (loss)		$ 30.7	$ 12.0	$ (12.3)	$ 2.8

[1] Other costs include the effects of foreign currency translation adjustments which were immaterial during the periods presented.