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AFS Securities (Amortized cost and fair value of AFS securities by contractual maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	$ 15,042
Maturing, After One Year But Within Five Years	222,213
Maturing, After Five Years But Within Ten Years	58,029
Maturing, After Ten Years	29,044
Securities With Variable Monthly Payments or Noncontractual Maturities	161,041
Amortized Cost	485,369	$ 325,966
Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less, Fair value	15,154
Maturing, After One Year But Within Five Years, Fair value	224,172
Maturing, After Five Years But Within Ten Years, Fair value	58,858
Maturing, After Ten Years, Fair value	30,157
Securities With Variable Monthly Payments or Noncontractual Maturities, Fair value	166,043
Total, Fair value	494,384	339,228
States and political subdivisions [Member]
Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	15,042
Maturing, After One Year But Within Five Years	60,038
Maturing, After Five Years But Within Ten Years	21,498
Maturing, After Ten Years	27,544
Securities With Variable Monthly Payments or Noncontractual Maturities	0
Amortized Cost	124,122	137,710
Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	128,689	143,656
Auction rate money market preferred [Member]
Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	0
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	3,200
Amortized Cost	3,200	3,200
Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	3,246	3,237
Mortgage-backed securities [Member]
Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	0
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	59,966
Amortized Cost	59,966	85,926
Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	62,030	88,652
Collateralized mortgage obligations [Member]
Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	0
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	97,875
Amortized Cost	97,875	97,430
Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	100,767	101,983
Corporate Debt Securities
Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	0
Maturing, After Five Years But Within Ten Years	6,150
Maturing, After Ten Years	1,500
Securities With Variable Monthly Payments or Noncontractual Maturities	0
Amortized Cost	7,650	1,700
Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract]
Total, Fair value	7,583	$ 1,700
US Treasury Securities
Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]
Maturing, Due in One Year or Less	0
Maturing, After One Year But Within Five Years	162,175
Maturing, After Five Years But Within Ten Years	30,381
Maturing, After Ten Years	0
Securities With Variable Monthly Payments or Noncontractual Maturities	0
Amortized Cost	$ 192,556

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- Definition

Available-for-sale Securities, Debt Maturities, With Variable Monthly Payments Or Without Single Maturity Date, Amortized Cost Basis

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- Definition

Amortized cost 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/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
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Amount 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/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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-Topic 326
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-Topic 320
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