Disclosures about Fair Value of Financial Instruments - Recurring Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Assets
Available-for-sale securities	$ 733,024	$ 739,473
Mutual funds	2,207	2,161
Derivative assets	28,041	9,838
Derivative liabilities	28,139	9,907
Mortgage-backed - GSE residential
Financial Assets
Available-for-sale securities	149,821	152,512
Collateralized mortgage obligations - GSE residential
Financial Assets
Available-for-sale securities	118,938	129,212
State and political subdivisions
Financial Assets
Available-for-sale securities	462,850	456,340
Corporate bonds
Financial Assets
Available-for-sale securities	1,415	1,409
Fair Value, Recurring
Financial Assets
Mutual funds	2,207	2,161
Derivative assets	28,041	9,838
Derivative liabilities	28,139	9,907
Fair Value, Recurring \| Mortgage-backed - GSE residential
Financial Assets
Available-for-sale securities	149,821	152,512
Fair Value, Recurring \| Collateralized mortgage obligations - GSE residential
Financial Assets
Available-for-sale securities	118,938	129,212
Fair Value, Recurring \| State and political subdivisions
Financial Assets
Available-for-sale securities	462,850	456,340
Fair Value, Recurring \| Corporate bonds
Financial Assets
Available-for-sale securities	1,415	1,409
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Recurring
Financial Assets
Mutual funds	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Recurring \| Mortgage-backed - GSE residential
Financial Assets
Available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Recurring \| Collateralized mortgage obligations - GSE residential
Financial Assets
Available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Recurring \| State and political subdivisions
Financial Assets
Available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Recurring \| Corporate bonds
Financial Assets
Available-for-sale securities	0	0
Significant Other Observable Inputs (Level 2) \| Fair Value, Recurring
Financial Assets
Mutual funds	2,207	2,161
Derivative assets	28,041	9,838
Derivative liabilities	28,139	9,907
Significant Other Observable Inputs (Level 2) \| Fair Value, Recurring \| Mortgage-backed - GSE residential
Financial Assets
Available-for-sale securities	149,821	152,512
Significant Other Observable Inputs (Level 2) \| Fair Value, Recurring \| Collateralized mortgage obligations - GSE residential
Financial Assets
Available-for-sale securities	118,938	129,212
Significant Other Observable Inputs (Level 2) \| Fair Value, Recurring \| State and political subdivisions
Financial Assets
Available-for-sale securities	462,850	456,340
Significant Other Observable Inputs (Level 2) \| Fair Value, Recurring \| Corporate bonds
Financial Assets
Available-for-sale securities	1,415	1,409
Unobservable Inputs (Level 3) \| Fair Value, Recurring
Financial Assets
Mutual funds	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Unobservable Inputs (Level 3) \| Fair Value, Recurring \| Mortgage-backed - GSE residential
Financial Assets
Available-for-sale securities	0	0
Unobservable Inputs (Level 3) \| Fair Value, Recurring \| Collateralized mortgage obligations - GSE residential
Financial Assets
Available-for-sale securities	0	0
Unobservable Inputs (Level 3) \| Fair Value, Recurring \| State and political subdivisions
Financial Assets
Available-for-sale securities	0	0
Unobservable Inputs (Level 3) \| Fair Value, Recurring \| Corporate bonds
Financial Assets
Available-for-sale securities	$ 0	$ 0

Amount of 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 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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