Fair Value Disclosures - Investments in Certain Entities Calculate Net Asset Value per Share (Parenthetical) (Detail) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] | ||
| Total Unfunded Commitments | $ 779 | $ 553 |
| Real Assets Funds [Member] | ||
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] | ||
| Total Unfunded Commitments | 299 | 203 |
| Total remaining Unfunded Commitments | 267 | 172 |
| Real Assets Funds [Member] | Consolidated Variable Interest Entities [Member] | ||
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] | ||
| Total Unfunded Commitments | 94 | 83 |
| Private Equity Funds Of Funds [Member] | Consolidated Variable Interest Entities [Member] | ||
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] | ||
| Total Unfunded Commitments | 7 | 9 |
| Amount of unfunded commitments contractually obligated to fund | $ 17 | $ 22 |