Loans and Allowance - Amortized Cost Basis Of Collateral Dependent Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2021		Mar. 31, 2021	Dec. 31, 2020		Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	$ 57,134			$ 56,156
Allowance on Collateral Dependent Loans	199,775	[1]	$ 201,082	130,648	[1]	$ 121,119	$ 99,454	$ 80,284
Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,106
Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	862
Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	47,834
Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,942
Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,981			3,291
Allowance on Collateral Dependent Loans	0			0		21,078	17,364	14,569
Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	408
Individuals' loans for household and other personal expenditures
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	1			2
Allowance on Collateral Dependent Loans	0			$ 0		$ 8,445	$ 5,752	$ 4,035
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	51,338
Commercial Real Estate | Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Commercial Real Estate | Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	562
Commercial Real Estate | Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	47,834
Commercial Real Estate | Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,942
Commercial Real Estate | Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Commercial Real Estate | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Commercial Real Estate | Individuals' loans for household and other personal expenditures
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	3,389
Residential | Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Residential | Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Residential | Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Residential | Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Residential | Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,981
Residential | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	408
Residential | Individuals' loans for household and other personal expenditures
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,407
Other | Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,106
Other | Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	300
Other | Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Other | Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Other | Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Other | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Other | Individuals' loans for household and other personal expenditures
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	1
Collateral Dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	6,426
Collateral Dependent | Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	727
Collateral Dependent | Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	117
Collateral Dependent | Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	4,943
Collateral Dependent | Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	238
Collateral Dependent | Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	334
Collateral Dependent | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	67
Collateral Dependent | Individuals' loans for household and other personal expenditures
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	$ 0

[1] Beginning January 1, 2021, the amount is based on the current expected credit loss methodology. Prior to January 1, 2021, the amount is based on the incurred loss methodology. See additional details in NOTE 1. GENERAL of these Notes to Consolidated Condensed Financial Statement.