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Investments Investments - Equity Investments (Details) - USD ($) $ in Millions | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Schedule of Equity Method Investments [Line Items] |  |
Other investments | $ 401 | $ 478
Real Estate [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 15 | 16
Hedge Funds, Multi-strategy [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 100 | 65
Interest Rate Contract [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 49 | 176
Illiquid Investments [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 56 | 51
Insurance Linked [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 3 | 3
Equity [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 40 | 55
Credit Index Product [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 66 | 66
Private Equity Funds [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 4 | 0
Emerging Market Debt [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 17 | 0
Equity investments in pooled funds [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 350 | 432
Priced Through Pricing Vendors [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 50 | 136
Priced Through Pricing Vendors [Member] | Interest Rate Contract [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 3 | 81
Priced Through Pricing Vendors [Member] | Equity [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 30 | 55
Priced Through Pricing Vendors [Member] | Emerging Market Debt [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 17 | $ 0
Commitments [Member] | Financial Support, Capital Contributions [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | 75 |
Commitments [Member] | Partnership Interest [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Other investments | $ 49 |

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