Fair Value Measurements (Fair Value of Financial Instruments) (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
ASSETS
Cash and Due from Banks	$ 4,654,200,000	$ 3,056,800,000
Federal Reserve and Other Central Bank Deposits	40,030,400,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,941,100,000	1,949,400,000
Federal Funds Sold	1,100,000,000
Balance at December 31	1,070,300,000	686,400,000
FAIR VALUE	22,879,300,000	23,315,400,000
Loans (excluding Leases)
Held for Sale	0	12,300,000
Deposits
Savings Certificates and Other Time	1,981,300,000	842,700,000
Non U.S. Offices Interest-Bearing	65,481,900,000	75,767,100,000
Federal Funds Purchased	1,896,900,000	200,000
Balance at December 31	567,200,000	531,900,000
Other Borrowings	7,592,300,000	3,583,800,000
Senior Notes	2,724,200,000	2,505,500,000
Unfunded Commitments		0
BOOK VALUE
ASSETS
Cash and Due from Banks	4,654,200,000	3,056,800,000
Federal Reserve and Other Central Bank Deposits	40,030,400,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,941,100,000	1,949,400,000
Federal Funds Sold	32,000,000.0
Balance at December 31	1,070,300,000	686,400,000
FAIR VALUE	25,036,100,000	23,564,500,000
Loans (excluding Leases)
Held for Investment	42,749,000,000	40,319,300,000
Held for Sale		12,300,000
Other Assets	1,476,900,000	1,275,300,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	56,468,900,000	83,318,600,000
Savings Certificates and Other Time	1,981,300,000	842,700,000
Non U.S. Offices Interest-Bearing	65,481,900,000	75,767,100,000
Federal Funds Purchased	1,896,900,000	200,000
Balance at December 31	567,200,000	531,900,000
Other Borrowings	7,592,300,000	3,583,800,000
Senior Notes	2,724,200,000	2,505,500,000
Long-Term Debt	2,066,200,000	1,145,700,000
Unfunded Commitments	218,900,000	289,300,000
Other Liabilities	73,200,000	75,500,000
FAIR VALUE
ASSETS
Cash and Due from Banks	4,654,200,000	3,056,800,000
Federal Reserve and Other Central Bank Deposits	40,030,400,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,941,100,000	1,949,400,000
Federal Funds Sold	32,000,000.0
Balance at December 31	1,070,300,000	686,400,000
FAIR VALUE	22,879,300,000	23,315,400,000
Loans (excluding Leases)
Held for Investment	42,636,500,000	40,208,200,000
Held for Sale		24,500,000
Other Assets	1,460,400,000	1,279,800,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	56,468,900,000	83,318,600,000
Savings Certificates and Other Time	1,976,100,000	843,800,000
Non U.S. Offices Interest-Bearing	65,481,900,000	75,767,100,000
Federal Funds Purchased	1,896,900,000	200,000
Balance at December 31	567,200,000	531,900,000
Other Borrowings	7,592,800,000	3,583,900,000
Senior Notes	2,729,800,000	2,591,400,000
Long-Term Debt	2,110,700,000	1,189,400,000
Unfunded Commitments	218,900,000	289,300,000
Other Liabilities	73,200,000	75,500,000
FAIR VALUE | LEVEL 1
ASSETS
Cash and Due from Banks	4,654,200,000	3,056,800,000
Federal Reserve and Other Central Bank Deposits	0	0
Interest-Bearing Deposits with Banks	0	0
Federal Funds Sold	0
Balance at December 31	0	0
FAIR VALUE	50,000,000.0	47,000,000.0
Loans (excluding Leases)
Held for Investment	0	0
Held for Sale		0
Other Assets	94,700,000	119,100,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	56,468,900,000	83,318,600,000
Savings Certificates and Other Time	0	0
Non U.S. Offices Interest-Bearing	0	0
Federal Funds Purchased	0	0
Balance at December 31	0	0
Other Borrowings	0	0
Senior Notes	0	0
Long-Term Debt	0	0
Unfunded Commitments	0	0
Other Liabilities	0	0
FAIR VALUE | LEVEL 2
ASSETS
Cash and Due from Banks	0	0
Federal Reserve and Other Central Bank Deposits	40,030,400,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,941,100,000	1,949,400,000
Federal Funds Sold	32,000,000.0
Balance at December 31	1,070,300,000	686,400,000
FAIR VALUE	22,829,300,000	23,268,400,000
Loans (excluding Leases)
Held for Investment	0	0
Held for Sale		24,500,000
Other Assets	1,365,700,000	1,160,700,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	0	0
Savings Certificates and Other Time	1,976,100,000	843,800,000
Non U.S. Offices Interest-Bearing	65,481,900,000	75,767,100,000
Federal Funds Purchased	1,896,900,000	200,000
Balance at December 31	567,200,000	531,900,000
Other Borrowings	7,592,800,000	3,583,900,000
Senior Notes	2,729,800,000	2,591,400,000
Long-Term Debt	2,110,700,000	1,189,400,000
Unfunded Commitments	218,900,000	289,300,000
Other Liabilities	0	0
FAIR VALUE | LEVEL 3
ASSETS
Cash and Due from Banks	0	0
Federal Reserve and Other Central Bank Deposits	0	0
Interest-Bearing Deposits with Banks	0	0
Federal Funds Sold	0
Balance at December 31	0	0
FAIR VALUE	0	0
Loans (excluding Leases)
Held for Investment	42,636,500,000	40,208,200,000
Held for Sale		0
Other Assets	0	0
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	0	0
Savings Certificates and Other Time	0	0
Non U.S. Offices Interest-Bearing	0	0
Federal Funds Purchased	0	0
Balance at December 31	0	0
Other Borrowings	0	0
Senior Notes	0	0
Long-Term Debt	0	0
Unfunded Commitments	0	0
Other Liabilities	$ 73,200,000	$ 75,500,000