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Fair Value Measurements - Quantitative and Qualitative Information (Details) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)
Quantitative information about Level 3 fair value measurements
Mortgage servicing rights, fair value	$ 5,320	$ 4,224
Securities available-for-sale, at fair value	715,188	496,178
Fair Value, Inputs, Level 3 [Member]
Quantitative information about Level 3 fair value measurements
Mortgage servicing rights, fair value	5,320	4,224
Securities available-for-sale, at fair value	5,560	4,319
US States and Political Subdivisions Debt Securities [Member]
Quantitative information about Level 3 fair value measurements
Securities available-for-sale, at fair value	238,952	249,259
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Quantitative information about Level 3 fair value measurements
Securities available-for-sale, at fair value	5,600		$ 4,800
Collateralized Mortgage Obligations [Member]
Quantitative information about Level 3 fair value measurements
Securities available-for-sale, at fair value	165,414	56,585
Recurring
Quantitative information about Level 3 fair value measurements
Mortgage servicing rights, fair value	5,320	4,224
Recurring | Fair Value, Inputs, Level 3 [Member]
Quantitative information about Level 3 fair value measurements
Mortgage servicing rights, fair value	5,320	4,224
Recurring | US States and Political Subdivisions Debt Securities [Member]
Quantitative information about Level 3 fair value measurements
Securities available-for-sale, at fair value	238,952	249,259
Recurring | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Quantitative information about Level 3 fair value measurements
Securities available-for-sale, at fair value	5,560	4,319
Recurring | Collateralized Mortgage Obligations [Member]
Quantitative information about Level 3 fair value measurements
Securities available-for-sale, at fair value	$ 165,414	$ 56,585
Recurring | Measurement Input, Discount Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum [Member]
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	11.0	11.0
Recurring | Measurement Input, Discount Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum [Member]
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	15.0	15.0
Recurring | Measurement Input, Discount Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Weighted Average [Member]
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	11.0	11.0
Recurring | Measurement Input, Constant Prepayment Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum [Member]
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	0.0	5.5
Recurring | Measurement Input, Constant Prepayment Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum [Member]
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	49.6	59.1
Recurring | Measurement Input, Constant Prepayment Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Weighted Average [Member]
Quantitative information about Level 3 fair value measurements
Servicing Asset, Measurement Input	15.5	19.5

X

- Definition

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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-Publisher FASB
-Name Accounting Standards Codification
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No definition available.

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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

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Value of input used to measure servicing asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
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