Accounting for Transfers and Servicing of Financial Assets and Variable Interest Entities - Investments in Community Development and Tax-advantaged VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Variable Interest Entity [Line Items]
Investment carrying amount	$ 683,606	$ 663,491
Unfunded capital and other commitments	627,573	607,720
Variable Interest Entity, Not Primary Beneficiary, Community Development and Tax-Advantaged Investments
Variable Interest Entity [Line Items]
Investment carrying amount	7,259	6,659
Unfunded capital and other commitments	4,104	3,619
Maximum exposure to loss	$ 8,959	$ 9,002