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Investments (Narrative) (Detail) $ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 USD ($) partnerships | Dec. 31, 2019 USD ($)
Investment [Line Items] |  |  |
Document Period End Date |  | Dec. 31, 2020 |
Limited partnerships number | partnerships |  | 130 |
Restricted assets in fixed maturities and short-term investments |  | $ 19,600 | $ 21,000
Restricted assets in cash |  | 89 | $ 109
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Purchase Price |  | 108 |
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date |  | 5 |
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Par Value |  | $ 144 |
Huatai Group [Member] |  |  |
Investment [Line Items] |  |  |
Ownership Percentage |  | 47.10% |
CHINA | Huatai Group [Member] |  |  |
Investment [Line Items] |  |  |
Ownership Percentage |  | 47.00% | 31.00%
Equity method investment, additional 15.3 ownership percentage obtained |  |  | 15.30%
Equity method investment, additional 7.1 percentage obtained |  | 7.10% |
CHINA | Huatai Life Insurance Co. [Member] |  |  |
Investment [Line Items] |  |  |
Ownership Percentage |  | 20.00% | 20.00%
Subsequent Event [Member] | CHINA | Huatai Group [Member] |  |  |
Investment [Line Items] |  |  |
Equity method investment, additional 7.1 percentage obtained | 7.10% |  |
Indirect Ownership [Member] | CHINA | Huatai Life Insurance Co. [Member] |  |  |
Investment [Line Items] |  |  |
Ownership Percentage |  | 37.50% |
Direct Ownership [Member] | CHINA | Huatai Life Insurance Co. [Member] |  |  |
Investment [Line Items] |  |  |
Ownership Percentage |  | 20.00% |

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