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Acquisitions and Sale of Businesses - Narrative on sale of businesses (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Sale of Businesses |  |  |  |  |
Sale of redeemable noncontrolling interests |  |  |  | $ (3) |
Income tax expense (benefit) |  |  | $ 122 | 247 | $ 119
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) |  | $ 122 | $ 247 | $ 119

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