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, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	$ 26.8	$ 28.3	$ 53.5	$ 56.7
Amortization Expense	23.8	24.5	47.7	49.0
Affordable Housing
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	21.8	22.4	43.5	44.8
Amortization Expense	19.3	19.8	38.8	39.6
New Markets
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	5.0	5.9	10.0	11.9
Amortization Expense	$ 4.5	$ 4.7	$ 8.9	$ 9.4