Investments (Rollforward of Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 4,146	$ 6,187	$ 3,347	$ 2,846
Additions for credit losses not previously recorded	97	439	1,044	4,895
Change in allowance on securities with previous allowance	(625)	(1,706)	(773)	(2,393)
Reduction for securities sold during the period	0	0	0	(428)
Ending balance	3,618	4,920	3,618	4,920
States, municipalities and territories
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	1,834	0	2,776
Additions for credit losses not previously recorded	0	0	0	0
Change in allowance on securities with previous allowance	0	(1,834)	0	(2,776)
Reduction for securities sold during the period	0	0	0	0
Ending balance	0	0	0	0
Corporate securities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	3,132	3,743	3,214	0
Additions for credit losses not previously recorded	0	0	0	3,825
Change in allowance on securities with previous allowance	(221)	(529)	(303)	(611)
Reduction for securities sold during the period	0		0	0
Ending balance	2,911	3,214	2,911	3,214
Residential mortgage backed securities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	67	610	133	70
Additions for credit losses not previously recorded	97	439	97	1,070
Change in allowance on securities with previous allowance	(67)	657	(133)	994
Reduction for securities sold during the period	0		0	(428)
Ending balance	97	1,706	97	1,706
Other asset backed securities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	947	0	0	0
Additions for credit losses not previously recorded	0	0	947	0
Change in allowance on securities with previous allowance	(337)	0	(337)	0
Reduction for securities sold during the period	0		0	0
Ending balance	$ 610	$ 0	$ 610	$ 0

Amount excluding accrued interest, of allowance for credit loss on 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
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

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- Definition

Amount, excluding accrued interest, of credit loss expense on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) with no credit loss previously recorded.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-9

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Amount, excluding accrued interest, of credit loss expense (reversal of expense) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) with previously recorded allowance and not intended to be sold and not more likely than not will be required to sell before recovery of amortized cost basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-9

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- Definition

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

+ References

No definition available.

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Amount, excluding accrued interest, of decrease in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) from sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-9

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