Supplemental Financial Information - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	$ 21.0	$ 23.4	$ 42.8
Total cash, cash equivalents and restricted cash	93.0	83.9	153.7	$ 231.4
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	70.5	59.0	108.9
Restricted cash - discontinued operations (a)	$ 1.5	$ 1.5	$ 2.0