Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net derivative gains (losses) arising during the period, net of tax expense (benefit)	$ 0.7	$ 0.5	$ 1.1	$ 0.5
Reclassification of losses into net (loss), net of tax expense	$ 0.2	$ 0.1	$ 0.0	$ (1.5)