Fair Value Disclosures - Investments in Certain Entities Calculate Net Asset Value per Share (Parenthetical) (Detail) - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] | ||
| Total Unfunded Commitments | $ 553 | $ 343 |
| Real Assets Funds [Member] | ||
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] | ||
| Total Unfunded Commitments | 203 | 130 |
| Amount of unfunded commitments contractually obligated to fund | 172 | 117 |
| 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 | 83 | 37 |
| 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 | 9 | 18 |
| Amount of unfunded commitments contractually obligated to fund | $ 22 | $ 22 |