Variable Interest Entities (Income Tax Credits and Other Tax Benefits and Amortization Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	$ 28.4	$ 27.0	$ 84.0	$ 80.6
Amortization Expense	25.8	24.0	76.6	71.8
Affordable Housing
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	24.2	21.9	72.3	65.5
Amortization Expense	21.9	19.6	65.6	58.5
New Markets
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	4.2	5.1	11.7	15.1
Amortization Expense	$ 3.9	$ 4.4	$ 11.0	$ 13.3