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Fair Value (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2023
Fair Value Measurements [Line Items]
Investments measured at net asset value based on an ownership interest in partners'	1.00%			1.00%
Transfer between Level 2 and Level 3	$ 0	$ 0	$ 0
Fair Value Measured Using NAV [Member]
Fair Value Measurements [Line Items]
Investments measured at fair value using net asset value	$ 97,400,000			$ 114,600,000
Investment, Type [Extensible Enumeration]	srt:PartnershipInterestMember			srt:PartnershipInterestMember
Level 3 [Member]
Fair Value Measurements [Line Items]
Investments measured at fair value using net asset value	$ 3,800,000			$ 3,800,000
Liabilities held	$ 0	$ 0	$ 0

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Percentage Of Investments Not Included In Fair Value Of Financial Instruments

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Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Indicates type of investment. Includes, but is not limited to, common stock, preferred stock, convertible security, fixed income security, government security, option purchased, warrant, loan participation and assignment, commercial paper, bankers' acceptance, certificates of deposit, short-term security, repurchase agreement, and other investment company.

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