Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	$ 38,986		$ 38,986		$ 50,419
Equity securities	476		476		613
Derivative assets	2,860		2,860		2,677
Liabilities:
Derivative liabilities	3,283		3,283		2,999
Pretax unrealized losses	(24)	$ (1,203)	(548)	$ (73)
Available-for-sale debt securities transferred to held-to-maturity securities
Liabilities:
Pretax unrealized losses	32		(930)
Residential Mortgage
Assets:
Residential mortgage loans	109	124	109	124	116
U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	3,506		3,506		4,336
Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	2		2		2
Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	4,369		4,369		4,912
Other securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	794		794		722
Liabilities:
FHLB, restricted stock holdings	293		293		224
FRB, restricted stock holdings	499		499		496
DTCC, restricted stock holdings	2		2		2
Level 3 | Interest rate contracts
Assets:
Derivative assets	6	10	6	10
Liabilities:
Derivative liabilities	6	$ 8	6	$ 8
Recurring
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	38,192		38,192		49,697
Trading debt securities	1,132		1,132		899
Equity securities	476		476		613
Residential mortgage loans held for sale	512		512		334
Derivative assets	2,860		2,860		2,677
Total assets	45,012		45,012		56,073
Liabilities:
Derivative liabilities	3,283		3,283		2,999
Short positions	234		234		107
Total liabilities	3,517		3,517		3,106
Recurring | Interest rate contracts
Assets:
Derivative assets	949		949		983
Liabilities:
Derivative liabilities	1,254		1,254		1,213
Recurring | Foreign exchange contracts
Assets:
Derivative assets	1,128		1,128		643
Liabilities:
Derivative liabilities	1,092		1,092		600
Recurring | Equity contracts
Liabilities:
Derivative liabilities	164		164		168
Recurring | Commodity contracts
Assets:
Derivative assets	783		783		1,051
Liabilities:
Derivative liabilities	773		773		1,018
Recurring | Servicing rights
Assets:
Servicing rights	1,731		1,731		1,737
Recurring | Residential Mortgage
Assets:
Residential mortgage loans	109		109		116
Recurring | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	3,506		3,506		4,336
Trading debt securities	601		601		647
Liabilities:
Short positions	104		104		31
Recurring | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	2		2		2
Trading debt securities	84		84		39
Recurring | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	4,757		4,757		10,282
Trading debt securities	7		7		6
Recurring | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	21,155		21,155		25,720
Recurring | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	4,403		4,403		4,445
Recurring | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	4,369		4,369		4,912
Trading debt securities	440		440		207
Liabilities:
Short positions	130		130		76
Recurring | Level 1
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	3,506		3,506		4,336
Trading debt securities	592		592		640
Equity securities	450		450		600
Residential mortgage loans held for sale	0		0		0
Derivative assets	71		71		205
Total assets	4,619		4,619		5,781
Liabilities:
Derivative liabilities	74		74		33
Short positions	104		104		31
Total liabilities	178		178		64
Recurring | Level 1 | Interest rate contracts
Assets:
Derivative assets	2		2		0
Liabilities:
Derivative liabilities	2		2		5
Recurring | Level 1 | Foreign exchange contracts
Assets:
Derivative assets	0		0		0
Liabilities:
Derivative liabilities	0		0		0
Recurring | Level 1 | Equity contracts
Liabilities:
Derivative liabilities	0		0		0
Recurring | Level 1 | Commodity contracts
Assets:
Derivative assets	69		69		205
Liabilities:
Derivative liabilities	72		72		28
Recurring | Level 1 | Servicing rights
Assets:
Servicing rights	0		0		0
Recurring | Level 1 | Residential Mortgage
Assets:
Residential mortgage loans	0		0		0
Recurring | Level 1 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	3,506		3,506		4,336
Trading debt securities	592		592		640
Liabilities:
Short positions	104		104		31
Recurring | Level 1 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Recurring | Level 1 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Recurring | Level 1 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Recurring | Level 1 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Recurring | Level 1 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Liabilities:
Short positions	0		0		0
Recurring | Level 2
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	34,686		34,686		45,361
Trading debt securities	540		540		259
Equity securities	26		26		13
Residential mortgage loans held for sale	512		512		334
Derivative assets	2,783		2,783		2,466
Total assets	38,547		38,547		48,433
Liabilities:
Derivative liabilities	3,039		3,039		2,792
Short positions	130		130		76
Total liabilities	3,169		3,169		2,868
Recurring | Level 2 | Interest rate contracts
Assets:
Derivative assets	941		941		977
Liabilities:
Derivative liabilities	1,246		1,246		1,202
Recurring | Level 2 | Foreign exchange contracts
Assets:
Derivative assets	1,128		1,128		643
Liabilities:
Derivative liabilities	1,092		1,092		600
Recurring | Level 2 | Equity contracts
Liabilities:
Derivative liabilities	0		0		0
Recurring | Level 2 | Commodity contracts
Assets:
Derivative assets	714		714		846
Liabilities:
Derivative liabilities	701		701		990
Recurring | Level 2 | Servicing rights
Assets:
Servicing rights	0		0		0
Recurring | Level 2 | Residential Mortgage
Assets:
Residential mortgage loans	0		0		0
Recurring | Level 2 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	9		9		7
Liabilities:
Short positions	0		0		0
Recurring | Level 2 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	2		2		2
Trading debt securities	84		84		39
Recurring | Level 2 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	4,757		4,757		10,282
Trading debt securities	7		7		6
Recurring | Level 2 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	21,155		21,155		25,720
Recurring | Level 2 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	4,403		4,403		4,445
Recurring | Level 2 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	4,369		4,369		4,912
Trading debt securities	440		440		207
Liabilities:
Short positions	130		130		76
Recurring | Level 3
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Equity securities	0		0		0
Residential mortgage loans held for sale	0		0		0
Derivative assets	6		6		6
Total assets	1,846		1,846		1,859
Liabilities:
Derivative liabilities	170		170		174
Short positions	0		0		0
Total liabilities	170		170		174
Recurring | Level 3 | Interest rate contracts
Assets:
Derivative assets	6		6		6
Liabilities:
Derivative liabilities	6		6		6
Recurring | Level 3 | Foreign exchange contracts
Assets:
Derivative assets	0		0		0
Liabilities:
Derivative liabilities	0		0		0
Recurring | Level 3 | Equity contracts
Liabilities:
Derivative liabilities	164		164		168
Recurring | Level 3 | Commodity contracts
Assets:
Derivative assets	0		0		0
Liabilities:
Derivative liabilities	0		0		0
Recurring | Level 3 | Servicing rights
Assets:
Servicing rights	1,731		1,731		1,737
Recurring | Level 3 | Residential Mortgage
Assets:
Residential mortgage loans	109		109		116
Recurring | Level 3 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Liabilities:
Short positions	0		0		0
Recurring | Level 3 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Recurring | Level 3 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Recurring | Level 3 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Recurring | Level 3 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Recurring | Level 3 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities (amortized cost of $43,596 and $55,789)	0		0		0
Trading debt securities	0		0		0
Liabilities:
Short positions	$ 0		$ 0		$ 0