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Business Developments and Risks and Uncertainties (Tables) | 6 Months Ended
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Jun. 30, 2017
Text Block [Abstract] |
Assets And Liabilities Held For Sale |
|  |  |  |  | As of |
| In millions |  | December 31, 2016 |
| Assets |  |  |  |
|  | Investments |  | $ | 466 |
|  | Cash and cash equivalents |  |  | 73 |
|  | Premiums receivable |  |  | 267 |
|  | Other assets |  |  | 19 |
|  | Valuation allowance |  |  | (270) |
|  | Total assets held for sale |  | $ | 555 |
| Liabilities |  |  |  |
|  | Unearned premium revenue |  | $ | 304 |
|  | Other liabilities |  |  | 42 |
|  | Total liabilities held for sale |  | $ | 346 |

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- Definition Tabular disclosure of assets and liabilities held for sale. + References No definition available. + Details
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