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Investment Information - Fair value option (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
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Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Investments accounted for using the fair value option | $ 3,749,575 | $ 3,663,477
Fixed maturities |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Investments accounted for using the fair value option | 1,019,529 | 754,452
Other investments |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Investments accounted for using the fair value option | 2,169,897 | 2,429,316
Short-term investments |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Investments accounted for using the fair value option | 468,704 | 377,014
Equity securities |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Investments accounted for using the fair value option | $ 91,445 | $ 102,695

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- Definition Certain fixed maturity securities, equity securities and other investments held at fair value under the fair value option afforded by accounting guidance regarding the fair value option for financial assets and liabilities. + References No definition available. + Details
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