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Investments - Narrative (Details) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2016 USD ($) | Sep. 30, 2015 USD ($) | Sep. 30, 2016 USD ($) security | Sep. 30, 2015 USD ($) | Dec. 31, 2015 USD ($)
Investment [Line Items] |  |  |  |  |
Percentage (based on amount of unrealized loss) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade |  |  | 49.00% |  |
Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade |  |  | 74.00% |  |
Other than temporary impairment charges | $ 16 | $ 35 | $ 107 | $ 69 |
Average life of ABS |  |  | 5 years |  |
Average life of MBS |  |  | 4 years |  |
Residential MBS |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Non-credit related portion of other-than-temporary impairment charges taken for securities still owned | 192 |  | $ 192 |  | $ 205
Fixed maturities, Gross Unrealized, Losses | (14) |  | (14) |  | (15)
Other than temporary impairment charges |  |  | 2 |  |
Securities with non-credit other-than-temporary impairment charges |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Gross Unrealized, Gains | 131 |  | 131 |  | 134
Gross Unrealized, Losses | (5) |  | (5) |  | (6)
Fixed maturities |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Fixed maturities, Gross Unrealized, Losses | (77) |  | $ (77) |  | (374)
Number of available for sale securities in an unrealized loss position | security |  |  | 475 |  |
Other than temporary impairment charges | 2 | $ 17 | $ 37 | $ 32 |
Corporate bonds |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Other than temporary impairment charges |  |  | $ 34 |  |
Common stocks |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Number of available for sale securities in an unrealized loss position | security |  |  | 32 |  |
Other than temporary impairment charges |  |  | $ 79 |  |
Equity securities, Gross Unrealized, Losses | (27) |  | $ (27) |  | (79)
Preferred stocks |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Number of available for sale securities in an unrealized loss position | security |  |  | 14 |  |
Other than temporary impairment charges |  |  | $ 4 |  |
Equity securities, Gross Unrealized, Losses | $ (3) |  | $ (3) |  | $ (6)
Number of available for sale securities in an unrealized loss position for twelve months or longer | Common stocks |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Number of available for sale securities in an unrealized loss position | security |  |  | 0 |  |
Number of available for sale securities in an unrealized loss position for twelve months or longer | Preferred stocks |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Number of available for sale securities in an unrealized loss position | security |  |  | 1 |  |

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