Derivatives and Hedging - Additional Information (Detail) - USD ($) $ in Millions |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Derivative [Line Items] | ||
| Derivative maximum risk of loss for credit protection | $ 17 | $ 17 |
| Forward Foreign Currency Exchange Contracts [Member] | ||
| Derivative [Line Items] | ||
| Notional value | 2,100 | 2,200 |
| Total Return Swaps [Member] | ||
| Derivative [Line Items] | ||
| Notional value | $ 522 | $ 483 |