Variable Interest Entities (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Variable Interest Entity [Line Items]
Assets	$ 159,839,600,000		$ 159,839,600,000		$ 183,889,800,000
Liabilities	148,809,200,000		148,809,200,000		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	26,100,000	$ 22,000,000	74,500,000	$ 68,100,000
Investment company, voluntary fee waived	2,600,000	$ 76,700,000	61,900,000	$ 206,700,000
Contractual obligation to provide financial support	0		0
Fair value investments, seed capital investments	18,100,000		18,100,000		0
Unfunded commitments	0		0		0
Other Assets
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, assets	892,600,000		892,600,000		916,800,000
Other Assets | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	854,900,000		854,900,000		880,000,000
Other Liabilities
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, liabilities	258,200,000		258,200,000		289,300,000
Other Liabilities | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Liabilities	$ 242,700,000		$ 242,700,000		$ 280,500,000