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Investments - Summary of Amounts Included in Net Realized (Losses) Gains and Other-Than-Temporary Impairments (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2023 | Mar. 31, 2022 | Dec. 31, 2022
Investment [Line Items] |  |  |
Foreign exchange (losses) gains | $ (2) | $ 1 |
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal) | (1) | (1) |
Debt Securities, Available-for-sale, Allowance for Credit Loss, Sell before Recovery | 0 | 0 |
Realized Investment Gains (Losses) | (4) | 10 |
Fair Value of Securities Deposited in Connection wtih Letter of Credit | 1 |  | $ 1
Debt Securities, Available-for-sale, Realized Gain | 0 | 23 |
Debt Securities, Available-for-sale, Realized Loss | 2 | 15 |
Gain (Loss) on Investments [Member] |  |  |
Investment [Line Items] |  |  |
Foreign exchange (losses) gains | $ (2) | $ 3 |

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- Definition Amount of expense (reversal of expense) for allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), not intended to be sold and not more likely than not will be required to sell before recovery of amortized cost basis, with previously recorded allowance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (f) -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 + Details
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- Definition Amount of decrease in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) from intent to sell or more likely than not will be required to sell before recovery of amortized cost basis. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (e) -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 + Details
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- Definition Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27357-111563 + Details
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