Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 23.5	$ 16.8	$ 40.8	$ (24.1)
Net derivative gains (losses) and other costs arising during the period, net of tax expense of $0.8; $5.8; $0.0; and $6.2, respectively	[1]	2.5	16.0	(0.2)	17.2
Reclassification of (gains) into net income (loss), net of tax (expense) of $(0.8); $(0.5); $(2.3); and $(1.5), respectively		(2.1)	(2.1)	(6.2)	(5.4)
Other comprehensive income (loss)		0.4	13.9	(6.4)	11.8
Comprehensive income (loss)		$ 23.9	$ 30.7	$ 34.4	$ (12.3)

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