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Segments of Operations - Narrative (Details) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 USD ($) | Jun. 30, 2016 USD ($) | Sep. 30, 2015 USD ($) | Jun. 30, 2015 USD ($) | Sep. 30, 2016 USD ($) segment | Sep. 30, 2015 USD ($)
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Number of segments | segment |  |  |  |  |  | 4 |
Other income |  | $ 46 |  | $ 43 |  | $ 172 | $ 185
Special charges related to the exit of certain lines of business within subsidiaries |  |  |  |  |  | 65 |
Property and Casualty Insurance |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Other income | [1] | 3 |  | 2 |  | $ 46 | $ 61
Property and Casualty Insurance | Real Estate Investment |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Other income |  |  | $ 32 |  | $ 51 |  |
Other |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Special charges to increase asbestos and environmental reserves |  | 5 |  | 12 |  |  |
Write off of deferred debt issuance cost due to the retirement of debt |  |  |  | 4 |  |  |
Other Lines |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Special charges related to the exit of certain lines of business within subsidiaries |  |  | $ 65 |  |  |  |
Special charges to increase asbestos and environmental reserves |  | $ 36 |  | $ 67 |  |  |
[1] | Includes pretax income of $32 million (before noncontrolling interest) from the sale of an apartment property in the second quarter of 2016 and $51 million (before noncontrolling interest) from the sale of the Le Pavillon Hotel in the second quarter of 2015.

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