| **Investments**            | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Investments [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Investments                | Note C. InvestmentsThe significant components of Net investment income are presented in the following table.Three months ended March 31   (In millions)2015 2014Fixed maturity securities$443 $452Short term investments2 1Limited partnership investments114 73Equity securities3 2Mortgage loans8 6Trading portfolio2 3Other— 2Gross investment income572 539Investment expense(14) (13)Net investment income$558 $526Net realized investment gains (losses) are presented in the following table.Three months ended March 31   (In millions)2015 2014Net realized investment gains (losses):   Fixed maturity securities:   Gross realized gains$33 $53Gross realized losses(21) (15)Net realized investment gains (losses) on fixed maturity securities12 38Equity securities:   Gross realized gains1 5Gross realized losses(1) —Net realized investment gains (losses) on equity securities— 5Derivatives(1) —Short term investments and other(1) 3Net realized investment gains (losses)$10 $46The components of Net other-than-temporary impairment (OTTI) losses recognized in earnings by asset type are presented in the following table.Three months ended March 31   (In millions)2015 2014Fixed maturity securities available-for-sale:   Corporate and other bonds$5 $1States, municipalities and political subdivisions5 —Asset-backed - residential mortgage-backed1 1Total fixed maturity securities available-for-sale11 2Equity securities available-for-sale:   Common stock1 —Net OTTI losses recognized in earnings$12 $2The following tables present a summary of fixed maturity and equity securities.March 31, 2015Cost orAmortizedCost GrossUnrealizedGains GrossUnrealizedLosses EstimatedFairValue UnrealizedOTTILosses (Gains)(In millions)    Fixed maturity securities available-for-sale:         Corporate and other bonds$16,721 $1,867 $43 $18,545 $—States, municipalities and political subdivisions11,407 1,536 9 12,934 —Asset-backed:         Residential mortgage-backed4,998 241 13 5,226 (51)Commercial mortgage-backed2,151 114 5 2,260 (3)Other asset-backed1,109 15 1 1,123 —Total asset-backed8,258 370 19 8,609 (54)U.S. Treasury and obligations of government-sponsored enterprises24 6 — 30 —Foreign government390 19 — 409 —Redeemable preferred stock39 3 — 42 —Total fixed maturity securities available-for-sale36,839 3,801 71 40,569 $(54)Total fixed maturity securities trading36   36  Equity securities available-for-sale:         Common stock41 9 — 50  Preferred stock172 7 4 175  Total equity securities available-for-sale213 16 4 225  Total$37,088 $3,817 $75 $40,830  December 31, 2014Cost orAmortizedCost GrossUnrealizedGains GrossUnrealizedLosses EstimatedFairValue UnrealizedOTTILosses (Gains)(In millions)    Fixed maturity securities available-for-sale:         Corporate and other bonds$17,210 $1,721 $61 $18,870 $—States, municipalities and political subdivisions11,285 1,463 8 12,740 —Asset-backed:         Residential mortgage-backed5,028 218 13 5,233 (53)Commercial mortgage-backed2,056 93 5 2,144 (2)Other asset-backed1,234 11 10 1,235 —Total asset-backed8,318 322 28 8,612 (55)U.S. Treasury and obligations of government-sponsored enterprises26 5 — 31 —Foreign government438 16 — 454 —Redeemable preferred stock39 3 — 42 —Total fixed maturity securities available-for-sale37,316 3,530 97 40,749 $(55)Total fixed maturity securities trading19   19  Equity securities available-for-sale:         Common stock38 9 — 47  Preferred stock172 5 2 175  Total equity securities available-for-sale210 14 2 222  Total$37,545 $3,544 $99 $40,990  The net unrealized gains on investments included in the tables above are recorded as a component of Accumulated other comprehensive income (AOCI).  When presented in AOCI, these amounts are net of tax and any required Shadow Adjustments.  As of March 31, 2015 and December 31, 2014, the net unrealized gains on investments included in AOCI were net of after-tax Shadow Adjustments of $1,370 million and $1,288 million.  To the extent that unrealized gains on fixed income securities supporting certain products within the Life & Group Non-Core segment would result in a premium deficiency if realized, a related decrease in Deferred acquisition costs and/or increase in Insurance reserves are recorded, net of tax, as a reduction of net unrealized gains through Other comprehensive income (loss) (Shadow Adjustments).The following tables present the estimated fair value and gross unrealized losses of fixed maturity and equity securities in a gross unrealized loss position by the length of time in which the securities have continuously been in that position. Less than 12 Months 12 Months or Longer TotalMarch 31, 2015EstimatedFair Value GrossUnrealizedLosses EstimatedFair Value GrossUnrealizedLosses EstimatedFair Value GrossUnrealizedLosses(In millions)     Fixed maturity securities available-for-sale:           Corporate and other bonds$840 $31 $139 $12 $979 $43States, municipalities and political subdivisions479 6 100 3 579 9Asset-backed:           Residential mortgage-backed318 5 148 8 466 13Commercial mortgage-backed175 3 62 2 237 5Other asset-backed187 1 5 — 192 1Total asset-backed680 9 215 10 895 19U.S. Treasury and obligations of government-sponsored enterprises3 — — — 3 —Foreign government13 — 1 — 14 —Total fixed maturity securities available-for-sale2,015 46 455 25 2,470 71Equity securities available-for-sale:           Preferred stock15 4 — — 15 4Total$2,030 $50 $455 $25 $2,485 $75 Less than 12 Months 12 Months or Longer TotalDecember 31, 2014EstimatedFair Value GrossUnrealizedLosses EstimatedFair Value GrossUnrealizedLosses EstimatedFair Value GrossUnrealizedLosses(In millions)     Fixed maturity securities available-for-sale:           Corporate and other bonds$1,330 $46 $277 $15 $1,607 $61States, municipalities and political subdivisions335 5 127 3 462 8Asset-backed:           Residential mortgage-backed293 5 189 8 482 13Commercial mortgage-backed264 2 99 3 363 5Other asset-backed607 10 7 — 614 10Total asset-backed1,164 17 295 11 1,459 28U.S. Treasury and obligations of government-sponsored enterprises3 — 4 — 7 —   Foreign government3 — 3 — 6 —Redeemable preferred stock3 — — — 3 —Total fixed maturity securities available-for-sale2,838 68 706 29 3,544 97Equity securities available-for-sale:        Preferred stock17 2 1 — 18 2Total$2,855 $70 $707 $29 $3,562 $99Based on current facts and circumstances, the Company believes the unrealized losses presented in the March 31, 2015 table above, are not indicative of the ultimate collectibility of the current amortized cost of the securities, but rather are primarily attributable to changes in interest rates and credit spreads, market illiquidity and other factors.  The Company has no current intent to sell securities with unrealized losses, nor is it more likely than not that it will be required to sell prior to recovery of amortized cost; accordingly, the Company has determined that there are no additional OTTI losses to be recorded as of March 31, 2015.The following table presents the activity related to the pretax credit loss component reflected in Retained earnings on fixed maturity securities still held as of March 31, 2015 and 2014 for which a portion of an OTTI loss was recognized in Other comprehensive income.Three months ended March 31   (In millions)2015 2014Beginning balance of credit losses on fixed maturity securities$62 $74Reductions for securities sold during the period(1) (2)Reductions for securities the Company intends to sell or more likely than not will be required to sell— (3)Ending balance of credit losses on fixed maturity securities$61 $69Contractual MaturityThe following table presents available-for-sale fixed maturity securities by contractual maturity. March 31, 2015 December 31, 2014(In millions)Cost orAmortizedCost EstimatedFairValue Cost orAmortizedCost EstimatedFairValueDue in one year or less$2,011 $2,043 $2,479 $2,511Due after one year through five years8,760 9,340 9,054 9,605Due after five years through ten years12,401 13,108 12,055 12,584Due after ten years13,667 16,078 13,728 16,049Total$36,839 $40,569 $37,316 $40,749Actual maturities may differ from contractual maturities because certain securities may be called or prepaid with or without call or prepayment penalties.  Securities not due at a single date are allocated based on weighted average life.Derivative Financial InstrumentsThe following tables present the aggregate contractual or notional amounts and estimated fair values related to derivative financial instruments.March 31, 2015Contractual/NotionalAmount Estimated Fair Value(In millions) Asset LiabilityWithout hedge designation     Currency forwards$18 $2 $—Equity warrants5 — —Embedded derivative on funds withheld liability184 — 5Total  $2 $5December 31, 2014Contractual/NotionalAmount Estimated Fair Value(In millions) Asset LiabilityWithout hedge designation     Currency forwards$9 $— $—Equity warrants5 — —Embedded derivative on funds withheld liability184 — 3Total  $— $3Derivative financial instruments are presented gross in Other invested assets and Other liabilities on the Condensed Consolidated Balance Sheets.  There would be no significant difference in the balance included in such accounts if the estimated fair values were presented net as of March 31, 2015 and December 31, 2014.Investment CommitmentsAs of March 31, 2015, the Company had committed approximately $338 million to future capital calls from various third-party limited partnership investments in exchange for an ownership interest in the related partnerships.As of March 31, 2015, the Company had mortgage loan commitments of $41 million representing signed loan applications received and accepted.The Company invests in various privately placed debt securities, including bank loans, as part of its overall investment strategy and has committed to additional future purchases, sales and funding.  As of March 31, 2015, the Company had commitments to purchase or fund additional amounts of $82 million and sell $71 million under the terms of such securities. |

| X                                                                                                                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The entire disclosure for investments, including all tables.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 6 -Section 10 -Paragraph (c) -Subparagraph (1)
+ Details**Name:**invest_InvestmentTextBlock**Namespace Prefix:**invest_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_InvestmentsAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |