Variable Interest Entities (Income Tax Credits and Other Tax Benefits and Amortization Expense) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	$ 31.4	$ 27.7
Amortization Expense	27.0	25.1
Affordable Housing
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	27.7	24.0
Amortization Expense	23.6	21.6
New Markets
Variable Interest Entity [Line Items]
Income Tax Credits and Other Income Tax Benefits	3.7	3.7
Amortization Expense	$ 3.4	$ 3.5