Fair Value Measurements (Fair Value of Financial Instruments) (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
ASSETS
Cash and Due from Banks	$ 4,492,800,000	$ 3,056,800,000
Federal Reserve and Other Central Bank Deposits	39,644,900,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,542,300,000	1,949,400,000
Securities Purchased under Agreements to Resell	1,166,200,000	686,400,000
Debt Securities - Held to Maturity	23,064,900,000	23,315,400,000
Deposits
Savings Certificates and Other Time	1,217,100,000	842,700,000
Non U.S. Offices Interest-Bearing	68,503,700,000	75,767,100,000
Federal Funds Purchased	4,364,800,000	200,000
Securities Sold Under Agreements to Repurchase	561,400,000	531,900,000
Other Borrowings	7,153,600,000	3,583,800,000
Senior Notes	2,707,400,000	2,505,500,000
Unfunded Commitments	0	0
BOOK VALUE
ASSETS
Cash and Due from Banks	4,492,800,000	3,056,800,000
Federal Reserve and Other Central Bank Deposits	39,644,900,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,542,300,000	1,949,400,000
Federal Funds Sold	30,100,000
Securities Purchased under Agreements to Resell	1,166,200,000	686,400,000
Debt Securities - Held to Maturity	25,249,800,000	23,564,500,000
Loans (excluding Leases)
Held for Investment	43,853,200,000	40,319,300,000
Held for Sale		12,300,000
Other Assets	1,401,300,000	1,275,300,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	58,826,600,000	83,318,600,000
Savings Certificates and Other Time	1,217,100,000	842,700,000
Non U.S. Offices Interest-Bearing	68,503,700,000	75,767,100,000
Federal Funds Purchased	4,364,800,000	200,000
Securities Sold Under Agreements to Repurchase	561,400,000	531,900,000
Other Borrowings	7,153,600,000	3,583,800,000
Senior Notes	2,707,400,000	2,505,500,000
Long-Term Debt	1,068,300,000	1,145,700,000
Unfunded Commitments	258,200,000	289,300,000
Other Liabilities	80,800,000	75,500,000
TOTAL ESTIMATED FAIR VALUE
ASSETS
Cash and Due from Banks	4,492,800,000	3,056,800,000
Federal Reserve and Other Central Bank Deposits	39,644,900,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,542,300,000	1,949,400,000
Federal Funds Sold	30,100,000
Securities Purchased under Agreements to Resell	1,166,200,000	686,400,000
Debt Securities - Held to Maturity	23,064,900,000	23,315,400,000
Loans (excluding Leases)
Held for Investment	43,450,600,000	40,208,200,000
Held for Sale		24,500,000
Other Assets	1,387,700,000	1,279,800,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	58,826,600,000	83,318,600,000
Savings Certificates and Other Time	1,204,500,000	843,800,000
Non U.S. Offices Interest-Bearing	68,503,700,000	75,767,100,000
Federal Funds Purchased	4,364,800,000	200,000
Securities Sold Under Agreements to Repurchase	561,400,000	531,900,000
Other Borrowings	7,149,300,000	3,583,900,000
Senior Notes	2,671,900,000	2,591,400,000
Long-Term Debt	1,045,400,000	1,189,400,000
Unfunded Commitments	258,200,000	289,300,000
Other Liabilities	80,800,000	75,500,000
TOTAL ESTIMATED FAIR VALUE | LEVEL 1
ASSETS
Cash and Due from Banks	4,492,800,000	3,056,800,000
Federal Reserve and Other Central Bank Deposits	0	0
Interest-Bearing Deposits with Banks	0	0
Federal Funds Sold	0
Securities Purchased under Agreements to Resell	0	0
Debt Securities - Held to Maturity	57,900,000	47,000,000.0
Loans (excluding Leases)
Held for Investment	0	0
Held for Sale		0
Other Assets	103,400,000	119,100,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	58,826,600,000	83,318,600,000
Savings Certificates and Other Time	0	0
Non U.S. Offices Interest-Bearing	0	0
Federal Funds Purchased	0	0
Securities Sold Under Agreements to Repurchase	0	0
Other Borrowings	0	0
Senior Notes	0	0
Long-Term Debt	0	0
Unfunded Commitments	0	0
Other Liabilities	0	0
TOTAL ESTIMATED FAIR VALUE | LEVEL 2
ASSETS
Cash and Due from Banks	0	0
Federal Reserve and Other Central Bank Deposits	39,644,900,000	64,582,200,000
Interest-Bearing Deposits with Banks	1,542,300,000	1,949,400,000
Federal Funds Sold	30,100,000
Securities Purchased under Agreements to Resell	1,166,200,000	686,400,000
Debt Securities - Held to Maturity	23,007,000,000	23,268,400,000
Loans (excluding Leases)
Held for Investment	0	0
Held for Sale		24,500,000
Other Assets	1,284,300,000	1,160,700,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	0	0
Savings Certificates and Other Time	1,204,500,000	843,800,000
Non U.S. Offices Interest-Bearing	68,503,700,000	75,767,100,000
Federal Funds Purchased	4,364,800,000	200,000
Securities Sold Under Agreements to Repurchase	561,400,000	531,900,000
Other Borrowings	7,149,300,000	3,583,900,000
Senior Notes	2,671,900,000	2,591,400,000
Long-Term Debt	1,045,400,000	1,189,400,000
Unfunded Commitments	258,200,000	289,300,000
Other Liabilities	0	0
TOTAL ESTIMATED 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
Securities Purchased under Agreements to Resell	0	0
Debt Securities - Held to Maturity	0	0
Loans (excluding Leases)
Held for Investment	43,450,600,000	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
Securities Sold Under Agreements to Repurchase	0	0
Other Borrowings	0	0
Senior Notes	0	0
Long-Term Debt	0	0
Unfunded Commitments	0	0
Other Liabilities	$ 80,800,000	$ 75,500,000