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Acquisitions and Sale of Businesses - Allocation of the purchase price of subsidiary (Details) - USD ($) $ in Millions | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Nov. 30, 2018 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Business Acquisitions [Line Items] |  |  |  |  |
Total purchase price |  | $ 3 | $ 0 | $ 36 |
Goodwill |  | $ 207 | $ 207 | $ 207 | $ 199
ABA Insurance Services |  |  |  |  |
Business Acquisitions [Line Items] |  |  |  |  |
Total purchase price | $ 30 |  |  |  |
Tangible assets acquired | 28 |  |  |  |
Liabilities acquired | 26 |  |  |  |
Net tangible assets acquire, at fair value | 2 |  |  |  |
Excess purchase price over net tangible assets acquired | 28 |  |  |  |
Intangible assets acquired | 25 |  |  |  |
Deferred tax on intangible assets acquired | (5) |  |  |  |
Goodwill | $ 8 |  |  |  |

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