Variable Interest Entities (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Variable Interest Entity [Line Items]
Assets	$ 157,786,300,000		$ 157,786,300,000		$ 183,889,800,000
Liabilities	146,716,600,000		146,716,600,000		171,873,000,000
Exposure to loss from liquidity arrangements and obligations to purchase assets	0		0
Affordable housing tax credits and other tax benefits	25,700,000	$ 23,100,000	48,400,000	$ 46,100,000
Investment company, voluntary fee waived	8,600,000	$ 79,800,000	59,300,000	$ 130,000,000
Contractual obligation to provide financial support	0		0
Other Assets
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, assets	899,100,000		899,100,000		916,800,000
Other Assets | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	860,200,000		860,200,000		880,000,000
Other Liabilities
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, liabilities	276,700,000		276,700,000		289,300,000
Other Liabilities | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Liabilities	$ 261,200,000		$ 261,200,000		$ 280,500,000