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Acquisitions and Sale of Businesses - Narrative on sale of businesses (Details) $ in Millions |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Dec. 24, 2015 USD ($) | Mar. 31, 2015 | Dec. 31, 2017 USD ($) policy | Dec. 31, 2016 USD ($) | Jun. 30, 2016 USD ($) | Sep. 30, 2015 USD ($) | Mar. 31, 2015 USD ($) | Dec. 31, 2017 USD ($) policy | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Nov. 30, 2015
Sale of Businesses |  |  |  |  |  |  |  |  |  |  |  |
Sale of redeemable noncontrolling interests |  |  |  |  |  |  |  |  | $ (3) |  |  |
Income tax expense (benefit) |  |  |  |  |  |  |  |  | 247 | $ 119 | $ 195 |
Long-term care insurance reserves |  |  |  | $ 39 | $ 37 |  |  |  | 39 | 37 |  |
Realized gains (losses) on subsidiaries |  |  |  |  |  |  |  |  | 0 | 2 | (161) |
Property and Casualty Group |  |  |  |  |  |  |  |  |  |  |  |
Sale of Businesses |  |  |  |  |  |  |  |  |  |  |  |
Realized gains (losses) on subsidiaries |  |  |  |  |  |  | $ 5 |  |  |  |  |
Neon Capital Limited |  |  |  |  |  |  |  |  |  |  |  |
Sale of Businesses |  |  |  |  |  |  |  |  |  |  |  |
Sale of redeemable noncontrolling interests |  |  |  | (3) |  |  |  |  |  |  |  |
Income tax expense (benefit) |  |  |  | (56) | (111) |  |  |  |  | (48) |  |
AFG |  |  |  |  |  |  |  |  |  |  |  |
Sale of Businesses |  |  |  |  |  |  |  |  |  |  |  |
Income tax expense (benefit) |  |  |  | $ (56) | $ (177) |  |  |  | 247 | 119 | $ 195 |
Run-off long-term care insurance business |  |  |  |  |  |  |  |  |  |  |  |
Sale of Businesses |  |  |  |  |  |  |  |  |  |  |  |
Net sale proceeds | [1] | $ 13 |  |  |  |  |  |  |  |  |  |
Potential additional sale proceeds based on the release of certain statutory liabilities of the legal entities sold |  |  |  |  |  |  |  |  | $ 13 |  |  |
Contingent capital support agreement amount |  | $ 35 |  |  |  |  |  |  |  |  |  |
Contingent capital support agreement term |  | 5 years |  |  |  |  |  |  |  |  |  |
Long-term care insurance reserves of business sold as a percentage of total long-term care insurance reserves |  |  |  |  |  |  |  |  |  |  |  | 96.00%
Total tax benefits proceeds from the sale of business |  |  |  |  |  |  |  |  |  | $ 97 |  |
Realized gains (losses) on subsidiaries |  | $ (166) |  |  |  | $ 2 |  | $ (162) |  |  |  |
Loss on subsidiaries, net of tax |  | $ (108) |  |  |  |  |  | $ (105) |  |  |  |
Carrying value of the assets and liabilities of business sold as a percentage of total assets and liabilities |  | 4.00% | 4.00% |  |  |  |  |  |  |  |  |
Run-off long-term care insurance business | AFG |  |  |  |  |  |  |  |  |  |  |  |
Sale of Businesses |  |  |  |  |  |  |  |  |  |  |  |
Number of long-term care insurance policies | policy |  |  |  | 1,600 |  |  |  |  | 1,600 |  |  |
Long-term care insurance reserves |  |  |  | $ 39 |  |  |  |  | $ 39 |  |  |
[1] | Includes the fair value of the potential additional consideration and capital maintenance agreement and is shown net of estimated expenses.

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