Fair Values of Assets and Liabilities - Balances of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Jun. 30, 2023		Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities netting		$ (3,037)			$ (4,551)
Derivative assets netting		(3,295)			(5,427)
Available-for-sale securities	[2]	69,221	[1],[3]		72,910
Mortgage loans held for sale		2,280			1,849
Mortgage servicing rights		3,633		$ 3,724	3,755	$ 3,707	$ 3,432	$ 2,953
Residential Mortgage-Backed Securities [Member] | Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		25,661			29,271
Commercial Mortgage-Backed Securities [Member] | Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		7,187			7,145
Commercial Mortgage-Backed Securities [Member] | Non Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		6			7
Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		7,451	[4]		4,323
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		4			6
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities total		7,612			6,148
Derivative assets total		4,101			2,445
Available-for-sale securities		69,221			72,910
Mortgage loans held for sale		2,280			1,849
Mortgage servicing rights		3,633			3,755
Other assets		2,246			2,004
Total		81,481			82,963
Short-term borrowings and other liabilities		1,945			1,689
Total		9,557			7,837
Fair Value, Measurements, Recurring [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities netting		(3,037)			(4,551)
Derivative assets netting		(3,295)			(5,427)
Available-for-sale securities		0			0
Mortgage loans held for sale		0			0
Mortgage servicing rights		0			0
Other assets		0			0
Total		(3,295)			(5,427)
Short-term borrowings and other liabilities		0			0
Total		(3,037)			(4,551)
Fair Value, Measurements, Recurring [Member] | U.S. Treasury and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		18,968			22,033
Fair Value, Measurements, Recurring [Member] | U.S. Treasury and Agencies [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Fair Value, Measurements, Recurring [Member] | Obligations of State and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		9,944			10,125
Fair Value, Measurements, Recurring [Member] | Obligations of State and Political Subdivisions [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		25,661			29,271
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		7,187			7,145
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Agency [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Non Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		6			7
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Non Agency [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		7,451			4,323
Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		4			6
Fair Value, Measurements, Recurring [Member] | Other [Member] | Netting and Collateral One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities before netting		0			4
Derivative assets before netting		2			9
Available-for-sale securities		14,112			13,723
Mortgage loans held for sale		0			0
Mortgage servicing rights		0			0
Other assets		470			248
Total		14,584			13,980
Short-term borrowings and other liabilities		202			125
Total		202			129
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		14,112			13,723
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Obligations of State and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Non Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities before netting		5,887			6,241
Derivative assets before netting		6,051			6,608
Available-for-sale securities		55,109			59,186
Mortgage loans held for sale		2,280			1,849
Mortgage servicing rights		0			0
Other assets		1,776			1,756
Total		65,216			69,399
Short-term borrowings and other liabilities		1,743			1,564
Total		7,630			7,805
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		4,856			8,310
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Obligations of State and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		9,944			10,124
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		25,661			29,271
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		7,187			7,145
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Non Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		6			7
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		7,451			4,323
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		4			6
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities before netting		4,762			4,454
Derivative assets before netting		1,343			1,255
Available-for-sale securities		0			1
Mortgage loans held for sale		0			0
Mortgage servicing rights		3,633			3,755
Other assets		0			0
Total		4,976			5,011
Short-term borrowings and other liabilities		0			0
Total		4,762			4,454
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Obligations of State and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			1
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member] | Non Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		0			0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		$ 0			$ 0

[1] Amortized cost excludes portfolio level basis adjustments of $(1) million.

[2] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.

[3] The weighted-average maturity of total held-to-maturity investment securities was 9.2 years at December 31, 2022, with a corresponding weighted-average yield of 2.18 percent. The weighted-average maturity of total available-for-sale investment securities was 7.4 years at December 31, 2022, with a corresponding weighted-average yield of 2.94 percent.

[4] Information related to asset and mortgage-backed securities included above is presented based upon weighted-average maturities that take into account anticipated future prepayments.