Derivative Financial Instruments - Classifications and Hedging Relationships (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	$ 300,572	$ 322,942
Derivative Asset, Fair Value, Gross	4,027	5,841
Derivative Liability, Fair Value, Gross	(3,536)	(3,663)
Derivative Asset [Abstract]
Amounts subject to master netting arrangements	(1,312)	(1,561)
Cash collateral (received) posted for amounts subject to master netting arrangements	(345)	(443)
Net Amount in Consolidated Balance Sheets	2,370	3,837
Derivative Liability [Abstract]
Amounts subject to master netting arrangements	1,312	1,561
Cash collateral (received) posted for amounts subject to master netting arrangements	1,638	1,547
Net amount	(586)	(555)
Fair value hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	25,401	17,765
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	(8)	0
Fair value hedges | Interest rate contracts | Swap | Long-term debt
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	12,690	0
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	(6)	0
Fair value hedges | Interest rate contracts | Swap | AFS securities
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	12,711	17,765
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	(2)	0
Not designated as hedges
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	275,171	305,177
Derivative Asset, Fair Value, Gross	4,027	5,841
Derivative Liability, Fair Value, Gross	(3,528)	(3,663)
Not designated as hedges | Client-related and other risk management
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	244,348	245,388
Derivative Asset, Fair Value, Gross	3,981	5,642
Derivative Liability, Fair Value, Gross	(3,506)	(3,582)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Swap
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	150,223	156,338
Derivative Asset, Fair Value, Gross	1,716	3,399
Derivative Liability, Fair Value, Gross	(733)	(862)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Options
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	23,659	25,386
Derivative Asset, Fair Value, Gross	43	45
Derivative Liability, Fair Value, Gross	(30)	(18)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Forward commitments
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	2,404	4,847
Derivative Asset, Fair Value, Gross	2	9
Derivative Liability, Fair Value, Gross	(5)	(11)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Other
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	2,927	2,573
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Client-related and other risk management | Equity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	34,232	31,152
Derivative Asset, Fair Value, Gross	1,582	1,856
Derivative Liability, Fair Value, Gross	(2,089)	(2,297)
Not designated as hedges | Client-related and other risk management | Credit Contract | Loans and leases
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	570	1,056
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	(2)	(5)
Not designated as hedges | Client-related and other risk management | Credit Contract | Risk participation agreements
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	8,145	7,802
Derivative Asset, Fair Value, Gross	0	1
Derivative Liability, Fair Value, Gross	(4)	(13)
Not designated as hedges | Client-related and other risk management | Credit Contract | Total Return Swap
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	1,445	1,296
Derivative Asset, Fair Value, Gross	3	13
Derivative Liability, Fair Value, Gross	(19)	(33)
Not designated as hedges | Client-related and other risk management | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	16,102	12,066
Derivative Asset, Fair Value, Gross	160	189
Derivative Liability, Fair Value, Gross	(156)	(219)
Not designated as hedges | Client-related and other risk management | Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	4,641	2,872
Derivative Asset, Fair Value, Gross	475	130
Derivative Liability, Fair Value, Gross	(468)	(124)
Not designated as hedges | Mortgage banking | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	11,941	21,453
Derivative Asset, Fair Value, Gross	38	192
Derivative Liability, Fair Value, Gross	(22)	(76)
Not designated as hedges | Mortgage banking | Interest rate contracts | Swap
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	441	687
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Mortgage banking | Interest rate contracts | Other
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	424	466
Derivative Asset, Fair Value, Gross	1	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Mortgage banking | Interest rate contracts | Interest rate lock commitments
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	4,163	8,609
Derivative Asset, Fair Value, Gross	30	186
Derivative Liability, Fair Value, Gross	(7)	(3)
Not designated as hedges | Mortgage banking | Interest rate contracts | When issued securities, forward rate agreements and forward commitments
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	6,913	11,691
Derivative Asset, Fair Value, Gross	7	6
Derivative Liability, Fair Value, Gross	(15)	(73)
Not designated as hedges | MSRs | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	18,882	38,336
Derivative Asset, Fair Value, Gross	8	7
Derivative Liability, Fair Value, Gross	0	(5)
Not designated as hedges | MSRs | Interest rate contracts | Swap
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	12,837	36,161
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	(5)
Not designated as hedges | MSRs | Interest rate contracts | Options
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	101	101
Derivative Asset, Fair Value, Gross	1	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | MSRs | Interest rate contracts | Other
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	2,017	760
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | MSRs | Interest rate contracts | When issued securities, forward rate agreements and forward commitments
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	3,927	1,314
Derivative Asset, Fair Value, Gross	7	7
Derivative Liability, Fair Value, Gross	$ 0	$ 0