| Available-for-Sale Securities Pledged as Collateral for Financing (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021 | 
|---|---|---|
| Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] | ||
| Available-for-sale securities, at fair value | $ 7,778,734 | $ 7,161,703 | 
| Asset Pledged as Collateral | ||
| Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] | ||
| Available-for-sale securities, at fair value | $ 7,400,000 | $ 7,000,000 | 
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Details 
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