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Investments (Narrative) (Detail) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 USD ($) Security | Mar. 31, 2018 USD ($) | Dec. 31, 2018 USD ($)
Investment [Line Items] |  |  |
Net unrealized appreciation (depreciation) included in OCI | $ 9 | $ (4) |
Unrealized appreciation(depreciation) portion of AOCI with OTTI included in AOCI | $ 3 |  | $ 1
Percentage of mortgage-backed securities represented by investments in US government agency bonds | 82.00% |  | 81.00%
Company Assumed Recovery Rate | 32.00% |  |
Moodys Historical Mean Recovery Rate | 42.00% |  |
Total number of fixed maturities | Security | 30,335 |  |
Number of fixed maturities in an unrealized loss position | Security | 10,095 |  |
Largest single unrealized loss in the fixed maturities | $ 6 |  |
Restricted assets in fixed maturities and short-term investments | 22,000 |  | $ 21,000
Restricted assets in cash | 122 |  | $ 93
Corporate securities |  |  |
Investment [Line Items] |  |  |
Credit losses recognized in net income | 6 | 0 |
Mortgage-backed securities |  |  |
Investment [Line Items] |  |  |
Credit losses recognized in net income | $ 0 | $ 0 |

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