Goodwill and Other Assets (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2023	Aug. 11, 2023	Dec. 31, 2022
Goodwill [Line Items]
Goodwill				$ 1,185.2	$ 1,173.2
Accumulated impairment losses				(470.9)	(470.9)
Fresh Start Adjustment				(93.3)
Beginning balance			$ 702.3
Divestitures	$ (4.2)
Goodwill, Foreign Currency Translation Gain (Loss)	(20.1)		12.0
Ending balance	596.7	$ 596.7	596.7
Global Retail [Member]
Goodwill [Line Items]
Goodwill				273.1	269.6
Accumulated impairment losses				(57.2)	(57.2)
Fresh Start Adjustment				(66.3)
Beginning balance			212.4
Divestitures	(4.2)
Goodwill, Foreign Currency Translation Gain (Loss)	(6.1)		3.5
Ending balance	139.3	$ 139.3	139.3
Segment Reporting, Additional Information about Entity's Reportable Segments		34 percent
Global Banking
Goodwill [Line Items]
Goodwill				912.1	903.6
Accumulated impairment losses				(413.7)	$ (413.7)
Fresh Start Adjustment				$ (27.0)
Beginning balance			489.9
Divestitures	0.0
Goodwill, Foreign Currency Translation Gain (Loss)	(14.0)		8.5
Ending balance	$ 457.4	$ 457.4	$ 457.4
Segment Reporting, Additional Information about Entity's Reportable Segments		43 percent