Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 33.7	$ (22.0)	$ 17.3	$ (40.9)
Net derivative gains (losses) and other costs arising during the period, net of tax expense (benefit) of $2.9; $0.4; $(0.9); and $0.4, respectively.	[1]	8.0	1.2	(2.6)	1.2
Reclassification of (gains) into net income (loss), net of tax (expense) of $(0.9); $(0.4); $(1.4); and $(1.0), respectively		(1.9)	(0.9)	(4.2)	(3.3)
Other comprehensive income (loss)		6.1	0.3	(6.8)	(2.1)
Comprehensive income (loss)		$ 39.8	$ (21.7)	$ 10.5	$ (43.0)

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