Investment Securities - Allowance for Credit Losses AFS (Details) $ in Thousands	9 Months Ended
Sep. 30, 2021 USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 312
Reduction due to sales	(11)
Net decrease in allowance on previously impaired securities	(301)
Ending balance	0
State and political subdivisions
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	217
Reduction due to sales	0
Net decrease in allowance on previously impaired securities	(217)
Ending balance	0
Other securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	95
Reduction due to sales	(11)
Net decrease in allowance on previously impaired securities	(84)
Ending balance	$ 0

Amount of expense (reversal of expense) for 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), not intended to be sold and not more likely than not will be required to sell before recovery of amortized cost basis, with previously recorded allowance.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
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- Details

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