Derivatives and Hedging Activities - Bifurcated Embedded Derivatives (Detail) - USD ($) $ in Millions |
Sep. 30, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Derivative [Line Items] | ||
| Embedded Derivative, Fair Value of Embedded Derivative Asset | $ 881 | $ 1,450 |
| Embedded Derivative, Fair Value of Embedded Derivative Liability | (1,389) | (1,220) |
| Embedded Derivative, Fair Value of Embedded Derivative, Net Liability | (508) | 230 |
| Notional amount | 42,070,294 | 38,600,406 |
| Embedded Derivatives Classified In Debt [Member] | ||
| Derivative [Line Items] | ||
| Notional amount | $ 11,765 | $ 12,548 |