Accounting for Transfers and Servicing of Financial Assets and Variable Interest Entities - Additional Information (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
Variable Interest Entity [Line Items]
Tax credits related to tax-advantaged investments		$ 144	$ 149	$ 283	$ 287
Investment tax credits		120	72	178	236
Expense related to tax-advantaged investments		145	$ 135	283	$ 265
Investments in VIEs		680,058		680,058		$ 663,491
Available-for-sale securities	[1]	79,799		79,799		69,706
Liabilities related to VIEs		623,173		623,173		607,720
Variable Interest Entity Not Primary Beneficiary | Minimum
Variable Interest Entity [Line Items]
Net investments in unconsolidated VIEs		1		1		1
Variable Interest Entity Not Primary Beneficiary | Maximum
Variable Interest Entity [Line Items]
Net investments in unconsolidated VIEs		71		71		86
Variable Interest Entity, Not Primary Beneficiary, Private Investment Funds and Partnerships
Variable Interest Entity [Line Items]
Investments in VIEs		254		254		219
Maximum exposure to loss		381		381		319
Variable Interest Entity, Not Primary Beneficiary, Securitization Vehicles | Senior Notes
Variable Interest Entity [Line Items]
Available-for-sale securities		4,100		4,100		5,300
Collateral held related to senior notes		4,800		4,800		6,100
Variable Interest Entity, Primary Beneficiary, Community Development and Tax-Advantaged Investments
Variable Interest Entity [Line Items]
Investments in VIEs		5,700		5,700		6,100
Liabilities related to VIEs		3,900		3,900		4,400
Variable Interest Entity, Primary Beneficiary, Tender Option Bond Program
Variable Interest Entity [Line Items]
Investments in VIEs		343		343		607
Liabilities related to VIEs		$ 218		$ 218		$ 381

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