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Investments - Narrative (Details) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2017 USD ($) | Jun. 30, 2016 USD ($) | Jun. 30, 2017 USD ($) security | Jun. 30, 2016 USD ($) | Dec. 31, 2016 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 |  |  | 74.00% |  |
Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade |  |  | 89.00% |  |
Other than temporary impairment charges | $ 9 | $ 39 | $ 15 | $ 91 |
Fixed maturities — all other |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Other than temporary impairment charges |  |  | 1 |  |
Residential MBS |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Non-credit related portion of other-than-temporary impairment charges taken for securities still owned | 169 |  | 169 |  | $ 189
Gross unrealized losses on fixed maturities | (10) |  | (10) |  | (13)
Securities with non-credit other-than-temporary impairment charges |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Gross unrealized gains | 138 |  | 138 |  | 130
Gross unrealized losses | (3) |  | (3) |  | (3)
Fixed maturities |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Gross unrealized losses on fixed maturities | (107) |  | $ (107) |  | (245)
Number of available for sale securities in an unrealized loss position | security |  |  | 799 |  |
Other than temporary impairment charges | 1 | $ 19 | $ 1 | $ 35 |
Corporate bonds |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Other than temporary impairment charges |  |  | $ 1 |  |
Common stocks |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Number of available for sale securities in an unrealized loss position | security |  |  | 23 |  |
Other than temporary impairment charges |  |  | $ 14 |  |
Gross unrealized losses on equity securities | (27) |  | $ (27) |  | (23)
Preferred stocks |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Number of available for sale securities in an unrealized loss position | security |  |  | 5 |  |
Other than temporary impairment charges |  |  | $ 6 |  |
Gross unrealized losses on equity securities | $ (1) |  | $ (1) |  | $ (7)
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 |  |  | 2 |  |
Maximum | Residential MBS |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Other than temporary impairment charges |  |  | $ 1 |  |

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