Derivative Instruments and Hedging Activities (Fair Value (Asset)/Liability of Credit Protection Sold) (Details) - Credit Protection Sold - USD ($) $ in Millions |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Credit Derivatives | ||
| Fair value (asset)/liability | $ 1,398 | $ (1,944) |
| CDSs | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | 1,384 | (1,960) |
| Single Name CDS | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | 285 | (1,277) |
| Single Name CDS | Investment Grade | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | (118) | (1,167) |
| Single Name CDS | Non-investment Grade | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | 403 | (110) |
| Index and Basket CDS | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | 1,099 | (683) |
| Index and Basket CDS | Investment Grade | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | (314) | (1,091) |
| Index and Basket CDS | Non-investment Grade | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | 1,413 | 408 |
| Other Credit Contracts | ||
| Credit Derivatives | ||
| Fair value (asset)/liability | $ 14 | $ 16 |