Accounting for Transfers and Servicing of Financial Assets and Variable Interest Entities - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Variable Interest Entity [Line Items]
Tax credits related to tax-advantaged investments		$ 139	$ 138
Investment tax credits		63	164
Expense related to tax-advantaged investments		138	$ 130
Investments in VIEs		683,606		$ 663,491
Available-for-sale securities	[1]	72,426		69,706
Liabilities related to VIEs		627,573		607,720
Variable Interest Entity Not Primary Beneficiary | Minimum
Variable Interest Entity [Line Items]
Net investments in unconsolidated VIEs		1		1
Variable Interest Entity Not Primary Beneficiary | Maximum
Variable Interest Entity [Line Items]
Net investments in unconsolidated VIEs		89		86
Variable Interest Entity, Not Primary Beneficiary, Private Investment Funds and Partnerships
Variable Interest Entity [Line Items]
Investments in VIEs		227		219
Maximum exposure to loss		317		319
Variable Interest Entity, Not Primary Beneficiary, Securitization Vehicles | Senior Notes
Variable Interest Entity [Line Items]
Available-for-sale securities		4,700		5,300
Collateral held related to senior notes		5,400		6,100
Variable Interest Entity, Primary Beneficiary, Community Development and Tax-Advantaged Investments
Variable Interest Entity [Line Items]
Investments in VIEs		6,000		6,100
Liabilities related to VIEs		4,200		4,400
Variable Interest Entity, Primary Beneficiary, Tender Option Bond Program
Variable Interest Entity [Line Items]
Investments in VIEs		476		607
Liabilities related to VIEs		$ 381		$ 381

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