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Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Impairments		$ (7,601)
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	$ 9,025	17,488
Assets, earnings	476	(927)
Assets, other comprehensive income	0	0
Assets, Impairments	0
Assets, purchases	0	0
Assets, (sales)	(57)	0
Assets, maturities	0	0
Assets. transfers out		65
Securities transferred into or out of level 3, net	37
Assets, ending balance	9,481	9,025
Level 3 | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	5,253	13,898
Assets, earnings	609	(1,044)
Assets, other comprehensive income	0	0
Assets, Impairments	0	(7,601)
Assets, purchases	0	0
Assets, (sales)	(57)	0
Assets, maturities	0	0
Assets. transfers out	0	0
Assets, ending balance	5,805	5,253
Level 3 | Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	1,558	2,599
Assets, earnings	611	(1,041)
Assets, other comprehensive income	0	0
Assets, Impairments	0	0
Assets, purchases	0	0
Assets, (sales)	0	0
Assets, maturities	0	0
Assets. transfers out	0	0
Assets, ending balance	2,169	1,558
Level 3 | Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	3,695	11,299
Assets, earnings	(2)	(3)
Assets, other comprehensive income	0	0
Assets, Impairments	0	(7,601)
Assets, purchases	0	0
Assets, (sales)	(57)	0
Assets, maturities	0	0
Assets. transfers out	0	0
Assets, ending balance	3,636	3,695
Level 3 | Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	3,772	3,590
Assets, earnings	(133)	117
Assets, other comprehensive income	0	0
Assets, Impairments	0
Assets, Impairments		0
Assets, purchases	0	0
Assets, (sales)	0	0
Assets, maturities	0	0
Assets. transfers out		65
Securities transferred into or out of level 3, net	37
Assets, ending balance	$ 3,676	$ 3,772

X

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
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-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

+ References

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-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
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-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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

+ References

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-Paragraph 2
-Subparagraph (c)
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- Definition

The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of an intangible asset (excluding goodwill) to fair value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 50
-Paragraph 3
-Subparagraph (b)
-SubTopic 30
-Topic 350
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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Impairment

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