Fair Value Measurements (Fair Value Option, Fair Value and Unpaid Principal Balance) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2021 |
Dec. 31, 2020 |
|
| Mortgage loans held for sale [Member] | ||
| Fair Value, Option, Quantitative Disclosures [Line Items] | ||
| Mortgages Held-for-sale, Fair Value Disclosure | $ 680 | $ 1,439 |
| Fair Value Option Mortgages Held For Sale Aggregate Unpaid Principal | 659 | 1,362 |
| Aggregate Fair Value Less Aggregate Unpaid Principal | 21 | 77 |
| Net gains (losses) resulting from changes in fair value | (56) | 63 |
| Commercial Mortgage Loans Held For Sale | ||
| Fair Value, Option, Quantitative Disclosures [Line Items] | ||
| Mortgages Held-for-sale, Fair Value Disclosure | 90 | 0 |
| Fair Value Option Mortgages Held For Sale Aggregate Unpaid Principal | 90 | 0 |
| Aggregate Fair Value Less Aggregate Unpaid Principal | $ 0 | $ 0 |