Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 6.1	$ 32.3	$ (7.4)	$ 28.3
Net derivative gains (losses) and other costs arising during the period, net of tax expense (benefit) of $1.0; $(0.7); $2.5 and $1.3, respectively)	2.7	(1.9)	6.7	3.9
Reclassification of (gains) into net income, net of tax (expense) of $(0.5); $(0.3); $(0.8) and $(1.1), respectively	(1.3)	(1.0)	(2.2)	(3.0)
Other comprehensive income (loss)	1.4	(2.9)	4.5	0.9
Comprehensive income (loss)	$ 7.5	$ 29.4	$ (2.9)	$ 29.2