Variable Interest Entities - Carrying Amounts and Classification of Significant Variable Interests (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 18,940	$ 17,675
Non-marketable and other equity securities	2,485	1,802
Accrued interest receivable and other assets	2,074	3,206
Total assets	190,996	115,511
Other liabilities	2,733	3,972
Long-term debt	1,925	844
Total liabilities	176,327	107,078
Maximum exposure to loss in unconsolidated VIEs	1,216	859
Investments in qualified affordable housing projects, net	920	616
Consolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	8	15
Non-marketable and other equity securities	762	422
Accrued interest receivable and other assets	24	1
Total assets	794	438
Other liabilities	17	1
Long-term debt	0
Total liabilities	17	1
Maximum exposure to loss in unconsolidated VIEs	777
Unconsolidated
Variable Interest Entity [Line Items]
Cash and cash equivalents	0	0
Non-marketable and other equity securities	1,216	859
Accrued interest receivable and other assets	6	0
Total assets	1,222	859
Other liabilities	471	370
Long-term debt	90
Total liabilities	561	370
Non-marketable securities | Unconsolidated
Variable Interest Entity [Line Items]
Maximum exposure to loss in unconsolidated VIEs	$ 1,216	$ 859