Fair Value Measurements - Fair Value Of Financial Instruments (Detail) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Cash and Due from Banks	$ 3,056,800,000	$ 4,389,500,000
Federal Reserve and Other Central Bank Deposits	64,582,200,000	55,503,600,000
Interest-Bearing Deposits with Banks	1,949,400,000	4,372,600,000
Securities Purchased under Agreements to Resell	686,400,000	1,596,500,000
Debt Securities
Available for sale	38,010,500,000	42,022,000,000
Held to maturity, fair value	23,315,400,000	17,797,400,000
Loans (excluding Leases)
Held for Sale	12,300,000	0
Client Security Settlement Receivables	1,941,200,000	1,160,200,000
Deposits
Savings Certificates and Other Time	842,700,000	937,100,000
Non U.S. Offices Interest-Bearing	75,767,100,000	71,198,400,000
Federal Funds Purchased	200,000	260,200,000
Securities Sold Under Agreements to Repurchase	531,900,000	39,800,000
Other Borrowings	3,583,800,000	4,011,500,000
Senior Notes	2,505,500,000	3,122,400,000
Long-Term Debt
Floating Rate Capital Debt	0	277,800,000
DERIVATIVE INSTRUMENTS
Assets	1,902,700,000	4,097,200,000
Liabilities	1,566,500,000	3,738,000,000
LEVEL 2
Debt Securities
Available for sale	35,600,000,000	39,200,000,000
BOOK VALUE
ASSETS
Cash and Due from Banks	3,056,800,000	4,389,500,000
Federal Reserve and Other Central Bank Deposits	64,582,200,000	55,503,600,000
Interest-Bearing Deposits with Banks	1,949,400,000	4,372,600,000
Securities Purchased under Agreements to Resell	686,400,000	1,596,500,000
Debt Securities
Available for sale	38,010,500,000	42,022,000,000
Held to maturity, fair value	23,564,500,000	17,791,100,000
Trading Account	300,000	500,000
Loans (excluding Leases)
Held for Investment	40,319,300,000	33,558,000,000
Held for Sale	12,300,000
Client Security Settlement Receivables	1,941,200,000	1,160,200,000
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	140,100,000	275,000,000.0
Community Development Investments	959,600,000	919,600,000
Employee Benefit and Deferred Compensation	218,400,000	215,800,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	83,318,600,000	71,742,500,000
Savings Certificates and Other Time	842,700,000	937,100,000
Non U.S. Offices Interest-Bearing	75,767,100,000	71,198,400,000
Federal Funds Purchased	200,000	260,200,000
Securities Sold Under Agreements to Repurchase	531,900,000	39,800,000
Other Borrowings	3,583,800,000	4,011,500,000
Senior Notes	2,505,500,000	3,122,400,000
Long-Term Debt
Subordinated Debt	1,145,700,000	1,189,300,000
Floating Rate Capital Debt		277,800,000
Floating Rate Capital Debt
Standby Letters of Credit	15,700,000	22,400,000
Loan Commitments	59,800,000	77,000,000.0
BOOK VALUE | Asset/Liability Management | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	245,300,000	15,600,000
Liabilities	25,500,000	311,800,000
BOOK VALUE | Asset/Liability Management | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	7,600,000	8,300,000
Liabilities	8,700,000	10,200,000
BOOK VALUE | Asset/Liability Management | Other Financial Derivatives
DERIVATIVE INSTRUMENTS
Liabilities	37,500,000	35,300,000
BOOK VALUE | Client-Related and Trading | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	1,962,100,000	4,245,100,000
Liabilities	1,973,300,000	4,410,700,000
BOOK VALUE | Client-Related and Trading | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	132,400,000	289,200,000
Liabilities	90,200,000	114,800,000
FAIR VALUE
ASSETS
Cash and Due from Banks	3,056,800,000	4,389,500,000
Federal Reserve and Other Central Bank Deposits	64,582,200,000	55,503,600,000
Interest-Bearing Deposits with Banks	1,949,400,000	4,372,600,000
Securities Purchased under Agreements to Resell	686,400,000	1,596,500,000
Debt Securities
Available for sale	38,010,500,000	42,022,000,000
Held to maturity, fair value	23,315,400,000	17,797,400,000
Trading Account	300,000	500,000
Loans (excluding Leases)
Held for Investment	40,208,200,000	34,017,500,000
Held for Sale	24,500,000
Client Security Settlement Receivables	1,941,200,000	1,160,200,000
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	140,100,000	275,000,000.0
Community Development Investments	959,600,000	919,600,000
Employee Benefit and Deferred Compensation	222,900,000	228,900,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	83,318,600,000	71,742,500,000
Savings Certificates and Other Time	843,800,000	943,000,000.0
Non U.S. Offices Interest-Bearing	75,767,100,000	71,198,400,000
Federal Funds Purchased	200,000	260,200,000
Securities Sold Under Agreements to Repurchase	531,900,000	39,800,000
Other Borrowings	3,583,900,000	4,012,700,000
Senior Notes	2,591,400,000	3,222,600,000
Long-Term Debt
Subordinated Debt	1,189,400,000	1,250,100,000
Floating Rate Capital Debt		264,600,000
Floating Rate Capital Debt
Standby Letters of Credit	15,700,000	22,400,000
Loan Commitments	59,800,000	77,000,000.0
FAIR VALUE | Asset/Liability Management | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	245,300,000	15,600,000
Liabilities	25,500,000	311,800,000
FAIR VALUE | Asset/Liability Management | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	7,600,000	8,300,000
Liabilities	8,700,000	10,200,000
FAIR VALUE | Asset/Liability Management | Other Financial Derivatives
DERIVATIVE INSTRUMENTS
Liabilities	37,500,000	35,300,000
FAIR VALUE | Client-Related and Trading | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	1,962,100,000	4,245,100,000
Liabilities	1,973,300,000	4,410,700,000
FAIR VALUE | Client-Related and Trading | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	132,400,000	289,200,000
Liabilities	90,200,000	114,800,000
FAIR VALUE | LEVEL 1
ASSETS
Cash and Due from Banks	3,056,800,000	4,389,500,000
Federal Reserve and Other Central Bank Deposits	0	0
Interest-Bearing Deposits with Banks	0	0
Securities Purchased under Agreements to Resell	0	0
Debt Securities
Available for sale	2,426,100,000	2,799,900,000
Held to maturity, fair value	47,000,000.0	90,000,000.0
Trading Account	0	0
Loans (excluding Leases)
Held for Investment	0	0
Held for Sale	0
Client Security Settlement Receivables	0	0
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	0	0
Community Development Investments	0	0
Employee Benefit and Deferred Compensation	119,100,000	138,600,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	83,318,600,000	71,742,500,000
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
Subordinated Debt	0	0
Floating Rate Capital Debt		0
Floating Rate Capital Debt
Standby Letters of Credit	0	0
Loan Commitments	0	0
FAIR VALUE | LEVEL 1 | Asset/Liability Management | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	0	0
FAIR VALUE | LEVEL 1 | Asset/Liability Management | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	0	0
FAIR VALUE | LEVEL 1 | Asset/Liability Management | Other Financial Derivatives
DERIVATIVE INSTRUMENTS
Liabilities	0	0
FAIR VALUE | LEVEL 1 | Client-Related and Trading | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	0	0
FAIR VALUE | LEVEL 1 | Client-Related and Trading | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	0	0
FAIR VALUE | LEVEL 2
ASSETS
Cash and Due from Banks	0	0
Federal Reserve and Other Central Bank Deposits	64,582,200,000	55,503,600,000
Interest-Bearing Deposits with Banks	1,949,400,000	4,372,600,000
Securities Purchased under Agreements to Resell	686,400,000	1,596,500,000
Debt Securities
Available for sale	35,584,400,000	39,222,100,000
Held to maturity, fair value	23,268,400,000	17,707,400,000
Trading Account	300,000	500,000
Loans (excluding Leases)
Held for Investment	0	0
Held for Sale	24,500,000
Client Security Settlement Receivables	1,941,200,000	1,160,200,000
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	140,100,000	275,000,000.0
Community Development Investments	959,600,000	919,600,000
Employee Benefit and Deferred Compensation	103,800,000	90,300,000
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	0	0
Savings Certificates and Other Time	843,800,000	943,000,000.0
Non U.S. Offices Interest-Bearing	75,767,100,000	71,198,400,000
Federal Funds Purchased	200,000	260,200,000
Securities Sold Under Agreements to Repurchase	531,900,000	39,800,000
Other Borrowings	3,583,900,000	4,012,700,000
Senior Notes	2,591,400,000	3,222,600,000
Long-Term Debt
Subordinated Debt	1,189,400,000	1,250,100,000
Floating Rate Capital Debt		264,600,000
Floating Rate Capital Debt
Standby Letters of Credit	0	0
Loan Commitments	0	0
FAIR VALUE | LEVEL 2 | Asset/Liability Management | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	245,300,000	15,600,000
Liabilities	25,500,000	311,800,000
FAIR VALUE | LEVEL 2 | Asset/Liability Management | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	7,600,000	8,300,000
Liabilities	8,700,000	10,200,000
FAIR VALUE | LEVEL 2 | Asset/Liability Management | Other Financial Derivatives
DERIVATIVE INSTRUMENTS
Liabilities	0	0
FAIR VALUE | LEVEL 2 | Client-Related and Trading | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	1,962,100,000	4,245,100,000
Liabilities	1,973,300,000	4,410,700,000
FAIR VALUE | LEVEL 2 | Client-Related and Trading | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	132,400,000	289,200,000
Liabilities	90,200,000	114,800,000
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
Securities Purchased under Agreements to Resell	0	0
Debt Securities
Available for sale	0	0
Held to maturity, fair value	0	0
Trading Account	0	0
Loans (excluding Leases)
Held for Investment	40,208,200,000	34,017,500,000
Held for Sale
Client Security Settlement Receivables	0	0
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	0	0
Community Development Investments	0	0
Employee Benefit and Deferred Compensation	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
Subordinated Debt	0	0
Floating Rate Capital Debt		0
Floating Rate Capital Debt
Standby Letters of Credit	15,700,000	22,400,000
Loan Commitments	59,800,000	77,000,000.0
FAIR VALUE | LEVEL 3 | Asset/Liability Management | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	0	0
FAIR VALUE | LEVEL 3 | Asset/Liability Management | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	0	0
FAIR VALUE | LEVEL 3 | Asset/Liability Management | Other Financial Derivatives
DERIVATIVE INSTRUMENTS
Liabilities	37,500,000	35,300,000
FAIR VALUE | LEVEL 3 | Client-Related and Trading | Foreign Exchange Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	0	0
FAIR VALUE | LEVEL 3 | Client-Related and Trading | Interest Rate Contracts
DERIVATIVE INSTRUMENTS
Assets	0	0
Liabilities	$ 0	$ 0