Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Assets:
Available-for-sale debt and other securities	[1]	$ 38,791		$ 50,419
Equity securities		380		613
Derivative assets		2,777		2,677
Liabilities:
Derivative liabilities		3,223		2,999
Pretax unrealized losses		(525)	$ 1,131
Available-for-sale debt securities transferred to held-to-maturity securities
Liabilities:
Pretax unrealized losses		(962)
Residential Mortgage
Assets:
Residential mortgage loans		113	128	116
U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		2,774		4,336
Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		2		2
Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		4,647		4,912
Other securities
Assets:
Available-for-sale debt and other securities		800		722
Liabilities:
FHLB, restricted stock holdings		301		224
FRB, restricted stock holdings		496		496
DTCC, restricted stock holdings		3		2
Level 3 | Interest rate contracts
Assets:
Derivative assets		6	11
Liabilities:
Derivative liabilities		6	$ 8
Recurring
Assets:
Available-for-sale debt and other securities		37,991		49,697
Trading debt securities		1,151		899
Equity securities		380		613
Residential mortgage loans held for sale		307		334
Derivative assets		2,777		2,677
Total assets		44,475		56,073
Liabilities:
Derivative liabilities		3,223		2,999
Short positions		240		107
Total liabilities		3,463		3,106
Recurring | Interest rate contracts
Assets:
Derivative assets		994		983
Liabilities:
Derivative liabilities		1,312		1,213
Recurring | Foreign exchange contracts
Assets:
Derivative assets		784		643
Liabilities:
Derivative liabilities		750		600
Recurring | Equity contracts
Liabilities:
Derivative liabilities		162		168
Recurring | Commodity contracts
Assets:
Derivative assets		999		1,051
Liabilities:
Derivative liabilities		999		1,018
Recurring | Servicing rights
Assets:
Servicing rights		1,756		1,737
Recurring | Residential Mortgage
Assets:
Residential mortgage loans		113		116
Recurring | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		2,774		4,336
Trading debt securities		630		647
Liabilities:
Short positions		133		31
Recurring | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		2		2
Trading debt securities		65		39
Recurring | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities		4,851		10,282
Trading debt securities		11		6
Recurring | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		21,283		25,720
Recurring | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		4,434		4,445
Recurring | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		4,647		4,912
Trading debt securities		445		207
Liabilities:
Short positions		107		76
Recurring | Level 1
Assets:
Available-for-sale debt and other securities		2,774		4,336
Trading debt securities		608		640
Equity securities		348		600
Residential mortgage loans held for sale		0		0
Derivative assets		128		205
Total assets		3,858		5,781
Liabilities:
Derivative liabilities		88		33
Short positions		133		31
Total liabilities		221		64
Recurring | Level 1 | Interest rate contracts
Assets:
Derivative assets		1		0
Liabilities:
Derivative liabilities		0		5
Recurring | Level 1 | Foreign exchange contracts
Assets:
Derivative assets		0		0
Liabilities:
Derivative liabilities		0		0
Recurring | Level 1 | Equity contracts
Liabilities:
Derivative liabilities		0		0
Recurring | Level 1 | Commodity contracts
Assets:
Derivative assets		127		205
Liabilities:
Derivative liabilities		88		28
Recurring | Level 1 | Servicing rights
Assets:
Servicing rights		0		0
Recurring | Level 1 | Residential Mortgage
Assets:
Residential mortgage loans		0		0
Recurring | Level 1 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		2,774		4,336
Trading debt securities		608		640
Liabilities:
Short positions		133		31
Recurring | Level 1 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Recurring | Level 1 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Recurring | Level 1 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0		0
Recurring | Level 1 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0		0
Recurring | Level 1 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Liabilities:
Short positions		0		0
Recurring | Level 2
Assets:
Available-for-sale debt and other securities		35,217		45,361
Trading debt securities		543		259
Equity securities		32		13
Residential mortgage loans held for sale		307		334
Derivative assets		2,643		2,466
Total assets		38,742		48,433
Liabilities:
Derivative liabilities		2,967		2,792
Short positions		107		76
Total liabilities		3,074		2,868
Recurring | Level 2 | Interest rate contracts
Assets:
Derivative assets		987		977
Liabilities:
Derivative liabilities		1,306		1,202
Recurring | Level 2 | Foreign exchange contracts
Assets:
Derivative assets		784		643
Liabilities:
Derivative liabilities		750		600
Recurring | Level 2 | Equity contracts
Liabilities:
Derivative liabilities		0		0
Recurring | Level 2 | Commodity contracts
Assets:
Derivative assets		872		846
Liabilities:
Derivative liabilities		911		990
Recurring | Level 2 | Servicing rights
Assets:
Servicing rights		0		0
Recurring | Level 2 | Residential Mortgage
Assets:
Residential mortgage loans		0		0
Recurring | Level 2 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		22		7
Liabilities:
Short positions		0		0
Recurring | Level 2 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		2		2
Trading debt securities		65		39
Recurring | Level 2 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities		4,851		10,282
Trading debt securities		11		6
Recurring | Level 2 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		21,283		25,720
Recurring | Level 2 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		4,434		4,445
Recurring | Level 2 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		4,647		4,912
Trading debt securities		445		207
Liabilities:
Short positions		107		76
Recurring | Level 3
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Equity securities		0		0
Residential mortgage loans held for sale		0		0
Derivative assets		6		6
Total assets		1,875		1,859
Liabilities:
Derivative liabilities		168		174
Short positions		0		0
Total liabilities		168		174
Recurring | Level 3 | Interest rate contracts
Assets:
Derivative assets		6		6
Liabilities:
Derivative liabilities		6		6
Recurring | Level 3 | Foreign exchange contracts
Assets:
Derivative assets		0		0
Liabilities:
Derivative liabilities		0		0
Recurring | Level 3 | Equity contracts
Liabilities:
Derivative liabilities		162		168
Recurring | Level 3 | Commodity contracts
Assets:
Derivative assets		0		0
Liabilities:
Derivative liabilities		0		0
Recurring | Level 3 | Servicing rights
Assets:
Servicing rights		1,756		1,737
Recurring | Level 3 | Residential Mortgage
Assets:
Residential mortgage loans		113		116
Recurring | Level 3 | U.S. Treasury and federal agencies securities
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Liabilities:
Short positions		0		0
Recurring | Level 3 | Obligations of states and political subdivisions securities
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Recurring | Level 3 | Agency mortgage-backed securities | Residential Mortgage
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Recurring | Level 3 | Agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0		0
Recurring | Level 3 | Non-agency mortgage-backed securities | Commercial
Assets:
Available-for-sale debt and other securities		0		0
Recurring | Level 3 | Asset-backed securities and other debt securities
Assets:
Available-for-sale debt and other securities		0		0
Trading debt securities		0		0
Liabilities:
Short positions		$ 0		$ 0

[1] Amortized cost of $43,400 and $55,789 at March 31, 2024 and December 31, 2023, respectively.