Disclosures about Fair Value of Assets and Liabilities - Quantitative Information about Unobservable Inputs (Details)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Quantitative information about unobservable inputs
Mortgage servicing rights	$ 69,978,000	$ 74,387,000
Available for sale securities	339,053,000	290,243,000
Mortgage servicing rights \| Level 3
Quantitative information about unobservable inputs
Mortgage servicing rights	69,978,000	74,387,000
Collateral-dependent impaired loans \| Level 3
Quantitative information about unobservable inputs
Collateral-dependent impaired loans	$ 1,306,000	$ 1,570,000
Collateral-dependent impaired loans \| Level 3 \| Minimum
Quantitative information about unobservable inputs
Marketability discount (as a percent)	0.44	0.37
Collateral-dependent impaired loans \| Level 3 \| Maximum
Quantitative information about unobservable inputs
Marketability discount (as a percent)	0.75	0.55
Municipals
Quantitative information about unobservable inputs
Available for sale securities	$ 5,951,000	$ 5,937,000
Discount Rate \| Mortgage servicing rights \| Minimum
Quantitative information about unobservable inputs
Servicing asset, measurement input	0.08
Discount Rate \| Mortgage servicing rights \| Level 3 \| Minimum
Quantitative information about unobservable inputs
Servicing asset, measurement input		0.08
Discount Rate \| Mortgage servicing rights \| Level 3 \| Maximum
Quantitative information about unobservable inputs
Servicing asset, measurement input	0.13	0.13
Constant Prepayment Rate \| Mortgage servicing rights \| Level 3 \| Minimum
Quantitative information about unobservable inputs
Servicing asset, measurement input	0.02	0.01
Constant Prepayment Rate \| Mortgage servicing rights \| Level 3 \| Maximum
Quantitative information about unobservable inputs
Servicing asset, measurement input	0.43	0.39
Interest Rate Lock Commitments \| Level 3
Quantitative information about unobservable inputs
Derivative assets	$ 2,079,000	$ 186,000
Interest Rate Lock Commitments \| Measurement Input, Maturity \| Level 3 \| Minimum
Quantitative information about unobservable inputs
Loan closing rates (as a percent)	0.56	0.73
Loan closing rates (as a percent)	0.56
Interest Rate Lock Commitments \| Measurement Input, Maturity \| Level 3 \| Maximum
Quantitative information about unobservable inputs
Loan closing rates (as a percent)	0.99	0.99
Loan closing rates (as a percent)	0.99

The fair value amount of impaired loans.

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- Definition

Value of input used to measure collateral-dependent impaired loans.

+ References

No definition available.

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- 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 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

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-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Value of input used to measure derivative asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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Value of input used to measure derivative liability.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

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Value of input used to measure servicing asset.

+ References

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