Variable Interest Entities (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Variable Interest Entity [Line Items]
Assets	$ 172,565,000,000		$ 183,889,800,000
Liabilities	161,155,200,000		171,873,000,000
Exposure to loss from liquidity arrangements and obligations to purchase assets	0
Affordable housing tax credits and other tax benefits	22,700,000	$ 23,000,000
Investment company, voluntary fee waived	50,700,000	$ 50,200,000
Contractual obligation to provide financial support	0
Other Assets
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, assets	916,500,000		916,800,000
Other Assets | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	876,400,000		880,000,000
Other Liabilities
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, liabilities	297,400,000		289,300,000
Other Liabilities | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Liabilities	$ 281,800,000		$ 280,500,000