Variable Interest Entities - Carrying Amounts and Classification of Significant Variable Interests (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 23,959	$ 17,675
Non-marketable and other equity securities	1,943	1,802
Accrued interest receivable and other assets	2,650	3,206
Total assets	163,399	115,511
Other liabilities	3,449	3,972
Total liabilities	151,432	107,078
Maximum exposure to loss in unconsolidated VIEs	955	859
Investments in qualified affordable housing projects, net	696	616
Consolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	13	15
Non-marketable and other equity securities	618	422
Accrued interest receivable and other assets	24	1
Total assets	655	438
Other liabilities	14	1
Total liabilities	14	1
Maximum exposure to loss in unconsolidated VIEs	641
Unconsolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	0	0
Non-marketable and other equity securities	955	859
Accrued interest receivable and other assets	0	0
Total assets	955	859
Other liabilities	415	370
Total liabilities	415	370
Non-marketable securities | Unconsolidated
Variable Interest Entity [Line Items]
Maximum exposure to loss in unconsolidated VIEs	$ 955	$ 859