Variable Interest Entities (Income Tax Credits and Other Tax Benefits and Amortization Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	$ 31.4	$ 27.9	$ 62.8	$ 55.5
Amortization Expense	27.0	25.8	53.9	50.9
Affordable Housing
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	27.7	24.0	55.4	48.0
Amortization Expense	23.6	22.2	47.1	43.8
New Markets
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	3.7	3.9	7.4	7.5
Amortization Expense	$ 3.4	$ 3.6	$ 6.8	$ 7.1