| **Fair Value (Tables)**                                                                                                             | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
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| **Fair Value Disclosures [Abstract]**                                                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| Assets and liabilities measured at fair value on a recurring basis                                                                  | Assets and liabilities measured at fair value on a recurring basis are presented in the following tables.March 31, 2015      TotalAssets/ Liabilitiesat Fair Value(In millions)Level 1 Level 2 Level 3 Assets       Fixed maturity securities:       Corporate and other bonds$29 $18,337 $186 $18,552States, municipalities and political subdivisions— 12,877 86 12,963Asset-backed:       Residential mortgage-backed— 4,994 232 5,226Commercial mortgage-backed— 2,196 64 2,260Other asset-backed— 570 553 1,123Total asset-backed— 7,760 849 8,609U.S. Treasury and obligations of government-sponsored enterprises29 1 — 30Foreign government37 372 — 409Redeemable preferred stock30 12 — 42Total fixed maturity securities125 39,359 1,121 40,605Equity securities149 63 13 225Derivative financial instruments— 2 — 2Other invested assets, excluding derivative financial instruments— 41 — 41Short term investments742 678 — 1,420Life settlement contracts, included in Other assets— — 79 79Total assets$1,016 $40,143 $1,213 $42,372Liabilities       Other liabilities$— $5 $— $5Total liabilities$— $5 $— $5December 31, 2014      TotalAssets/Liabilitiesat Fair Value(In millions)Level 1 Level 2 Level 3 Assets       Fixed maturity securities:       Corporate and other bonds$32 $18,695 $162 $18,889States, municipalities and political subdivisions— 12,646 94 12,740Asset-backed:       Residential mortgage-backed— 5,044 189 5,233Commercial mortgage-backed— 2,061 83 2,144Other asset-backed— 580 655 1,235Total asset-backed— 7,685 927 8,612U.S. Treasury and obligations of government-sponsored enterprises28 3 — 31Foreign government41 413 — 454Redeemable preferred stock30 12 — 42Total fixed maturity securities131 39,454 1,183 40,768Equity securities145 61 16 222Other invested assets— 41 — 41Short term investments681 963 — 1,644Life settlement contracts, included in Other assets— — 82 82Total assets$957 $40,519 $1,281 $42,757Liabilities       Other liabilities$— $3 $— $3Total liabilities$— $3 $— $3                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Table of reconciliation for assets and liablities measured at fair value on a recurring basis using significant unobservable inputs | The following tables present a reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3).Level 3(In millions)Balance as ofJanuary 1,2015 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in Net income (loss) Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers intoLevel 3 Transfers out of Level 3 Balance as ofMarch 31, 2015 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2015 recognized in Net income  (loss)Fixed maturity securities:                   Corporate and other bonds$162 $1 $— $12 $(12) $(14) $37 $— $186 $—States, municipalities and political subdivisions94 1 — — — (9) — — 86 —Asset-backed:                   Residential mortgage-backed189 1 — 72 — (10) — (20) 232 —Commercial mortgage-backed83 1 1 6 — (1) — (26) 64 —Other asset-backed655 1 9 35 (144) (3) — — 553 —Total asset-backed927 3 10 113 (144) (14) — (46) 849 —Total fixed maturity securities1,183 5 10 125 (156) (37) 37 (46) 1,121 —Equity securities16 — (3) — — — — — 13 —Life settlement contracts82 13 — — — (16) — — 79 1Total$1,281 $18 $7 $125 $(156) $(53) $37 $(46) $1,213 $1Level 3(In millions)Balance as ofJanuary 1,2014 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in Net income (loss) Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers intoLevel 3 Transfers out of Level 3 Balance as ofMarch 31, 2014 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2014 recognized in Net income  (loss)Fixed maturity securities:                   Corporate and other bonds$204 $1 $1 $5 $(4) $(5) $3 $(16) $189 $—States, municipalities and political subdivisions71 — 1 — — — 14 — 86 —Asset-backed:                   Residential mortgage-backed331 1 15 25 — (21) 21 (13) 359 —Commercial mortgage-backed151 1 (1) — — (1) — (24) 126 —Other asset-backed446 1 — 148 (83) (72) — (1) 439 —Total asset-backed928 3 14 173 (83) (94) 21 (38) 924 —Total fixed maturity securities1,203 4 16 178 (87) (99) 38 (54) 1,199 —Equity securities11 3 (4) — (8) — — — 2 —Life settlement contracts88 10 — — — (11) — — 87 1Separate account business1 — — — — — — (1) — —Total$1,303 $17 $12 $178 $(95) $(110) $38 $(55) $1,288 $1 |
| Quantitative information about significant unobservable inputs in the fair value measurement of level 3 assets                      | The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurements of Level 3 assets.  Valuations for assets and liabilities not presented in the table below are primarily based on broker/dealer quotes for which there is a lack of transparency as to inputs used to develop the valuations.  The quantitative detail of these unobservable inputs is neither provided nor reasonably available to the Company.March 31, 2015       (In millions)Fair Value  Valuation Technique(s) Unobservable Input(s) Range (Weighted Average)Fixed maturity securities$102 Discounted cash flow Credit spread  2% - 13% (3%)Equity securities13 Market approach Private offering price $10 - $4,400 per share ($682)Life settlement contracts79 Discounted cash flow Discount rate risk premium 9%     Mortality assumption 55% - 1676% (164%)December 31, 2014       (In millions)Fair Value  Valuation Technique(s) Unobservable Input(s) Range (Weighted Average)Fixed maturity securities$101 Discounted cash flow Credit spread  2% - 13% (3%)Equity securities16 Market approach Private offering price $12 - $4,391 per share ($600)Life settlement contracts82 Discounted cash flow Discount rate risk premium 9%     Mortality assumption 55% - 1676% (163%)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Carrying amount and estimated fair value of financial instrument assets and liabilities not measured at fair value                  | The carrying amount and estimated fair value of the Company's financial assets and liabilities which are not measured at fair value on the Condensed Consolidated Balance Sheets are presented in the following tables.March 31, 2015CarryingAmount Estimated Fair Value(In millions) Level 1 Level 2 Level 3 TotalAssets         Notes receivable for the issuance of common stock$1 $— $— $1 $1Mortgage loans586 — — 612 612Liabilities         Long term debt$2,560 $— $2,908 $— $2,908December 31, 2014CarryingAmount Estimated Fair Value(In millions) Level 1 Level 2 Level 3 TotalAssets         Notes receivable for the issuance of common stock$1 $— $— $1 $1Mortgage loans588 — — 608 608Liabilities         Long term debt$2,559 $— $2,883 $— $2,883                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |

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| - Definition
Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.
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| - Definition
Tabular disclosure of the fair value of financial instruments, including financial assets and financial liabilities, and the measurements of those instruments, assets, and liabilities.
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| - Definition
Tabular disclosure of quantitative information about the inputs used in the fair value measurement of assets. This disclosure may include, but is not limited to, the fair value of the asset, valuation technique used to measure fair value, the inputs used to measure fair value, the ranges of the inputs, and the weighted averages of the inputs.
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| - Definition
Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).
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