Variable Interest Entities (Income Tax Credits and Other Tax Benefits and Amortization Expense) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	$ 26.7	$ 28.3
Amortization Expense	23.9	24.5
Affordable Housing
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	21.7	22.4
Amortization Expense	19.5	19.8
New Markets
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	5.0	5.9
Amortization Expense	$ 4.4	$ 4.7