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Investments Investments (Components Of Restricted Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Components Of Restricted Assets [Line Items]
Restricted assets	$ 5,499,358	$ 5,244,923
Assets held in trust or on deposit to support underwriting activities [Member]
Components Of Restricted Assets [Line Items]
Restricted assets	5,048,857	4,807,135
Assets pledged as security for letters of credit [Member]
Components Of Restricted Assets [Line Items]
Restricted assets	$ 450,501	$ 437,788

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- Definition

[Line Items] for Components Of Restricted Assets [Table]

+ References

No definition available.

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- Definition

Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480632/954-210-45-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480602/954-210-50-2

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