Investments -Schedule of the Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 0	$ 0
Recoveries of amounts previously written off during the year		34
(Increase) in allowance for credit losses		(106)
Ending balance	(106)	(19)
Credit losses (gains from recoveries) on AFS securities	106	(34)
Adoption of accounting standard
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance		(53)
Obligations of state and political subdivisions
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0
Recoveries of amounts previously written off during the year		1
(Increase) in allowance for credit losses		0
Ending balance	0	0
Obligations of state and political subdivisions \| Adoption of accounting standard
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance		(1)
Corporate securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0
Recoveries of amounts previously written off during the year		31
(Increase) in allowance for credit losses		(101)
Ending balance	(101)	(19)
Corporate securities \| Adoption of accounting standard
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance		(50)
Asset backed securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0
Recoveries of amounts previously written off during the year		2
(Increase) in allowance for credit losses		0
Ending balance	0	0
Asset backed securities \| Adoption of accounting standard
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance		(2)
Obligations of foreign governments
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0
Recoveries of amounts previously written off during the year		0
(Increase) in allowance for credit losses		(5)
Ending balance	$ (5)	0
Obligations of foreign governments \| Adoption of accounting standard
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance		$ 0

Amount 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

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Amount of increase (decrease) in allowance for credit loss of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455

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Amount of increase 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 recovery.

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Amount of expense (reversal of expense) for expected 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 change in present value of expected cash flows.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
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-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82922868-210454

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