Variable Interest Entities Affordable Housing Tax Credit Investments (Details) - Low Income Housing Tax Credit Investments [Member] - Variable Interest Entity, Not Primary Beneficiary [Member] - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Variable Interest Entity [Line Items] | |||
| Affordable housing tax credit investments included in other assets | $ 975 | $ 932 | |
| Unfunded affordable housing tax credit commitments included in other liabilities | 249 | 213 | |
| Loans and letters of credit commitments | 243 | 265 | |
| Funded portion of loans and letters of credit commitments | 130 | 157 | |
| Tax credits and other tax benefits recognized | 164 | 165 | $ 174 |
| Tax credit amortization expense included in provision for income taxes | $ 133 | $ 131 | $ 137 |