Derivatives and Hedging Activities - Bifurcated Embedded Derivatives (Detail) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Derivative [Line Items] | ||
| Embedded Derivative, Fair Value of Embedded Derivative Asset | $ 1,450 | $ 1,148 |
| Embedded Derivative, Fair Value of Embedded Derivative Liability | (1,220) | (1,717) |
| Embedded Derivative, Fair Value of Embedded Derivative, Net Liability | 230 | (569) |
| Notional amount | 38,600,406 | 39,750,315 |
| Embedded Derivatives Classified In Debt [Member] | ||
| Derivative [Line Items] | ||
| Notional amount | $ 12,548 | $ 11,003 |