Accounting for Transfers and Servicing of Financial Assets and Variable Interest Entities - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended			9 Months Ended			12 Months Ended
		Sep. 30, 2023		Sep. 30, 2022	Sep. 30, 2023		Sep. 30, 2022	Dec. 31, 2022
Variable Interest Entity [Line Items]
Assets related to consolidated VIEs		$ 668,039			$ 668,039			$ 674,805
Liabilities related to consolidated VIEs		614,461			614,461			623,573
Available-for-sale securities	[2]	67,207	[1],[3]		67,207	[1],[3]		72,910
Community Development And Tax Advantaged Investments [Member]
Variable Interest Entity [Line Items]
Federal and state income tax credits recognized in tax expense		148		$ 111	435		$ 336
Expense related to investments		134		102	399		310
Investment tax credits		238		$ 117	474		292
Financial Support Waived Fees [Member]
Variable Interest Entity [Line Items]
Financial or other support to money market funds							$ 65
Variable Interest Entity Not Primary Beneficiary [Member] | Private Investment Funds and Partnerships [Member]
Variable Interest Entity [Line Items]
Maximum exposure to loss		320			320			310
Assets related to consolidated VIEs		210			210			177
Variable Interest Entity Not Primary Beneficiary [Member] | Community Development And Tax Advantaged Investments [Member]
Variable Interest Entity [Line Items]
Maximum exposure to loss		10,058			10,058			9,761
Assets related to consolidated VIEs		6,488			6,488			5,452
Liabilities related to consolidated VIEs		3,186			3,186			2,416
Variable Interest Entity Not Primary Beneficiary [Member] | Minimum [Member]
Variable Interest Entity [Line Items]
Aggregate amount of investments in unconsolidated VIEs		1			1			1
Variable Interest Entity Not Primary Beneficiary [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Aggregate amount of investments in unconsolidated VIEs		126			126			116
Variable Interest Entity Primary Beneficiary [Member] | Senior Notes [Member]
Variable Interest Entity [Line Items]
Available-for-sale securities		5,900			5,900			3,400
Collateral held related to senior notes					6,800			4,000
Variable Interest Entity Primary Beneficiary [Member] | Community Development And Tax Advantaged Investments [Member]
Variable Interest Entity [Line Items]
Assets related to consolidated VIEs		5,900			5,900			5,900
Liabilities related to consolidated VIEs		4,400			4,400			4,200
Variable Interest Entity Primary Beneficiary [Member] | Tender Option Bond Program [Member]
Variable Interest Entity [Line Items]
Assets related to consolidated VIEs		941			941			1,500
Liabilities related to consolidated VIEs		$ 333			$ 333			$ 1,000

[1] Amortized cost excludes portfolio level basis adjustments of $(95) 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.