Loans and Allowance - Amortized Cost Basis Of Collateral Dependent Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2021		Jun. 30, 2021	Dec. 31, 2020		Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	$ 49,643			$ 56,156
Allowance on Collateral Dependent Loans	199,972	[1]	$ 199,775	130,648	[1]	$ 126,726	$ 121,119	$ 80,284
Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	17,450
Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	300
Construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	15
Allowance on Collateral Dependent Loans	17,640		$ 17,077	10,284
Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	26,703
Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	1,846
Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	2,927			3,291
Allowance on Collateral Dependent Loans	0			$ 0		$ 22,047	$ 21,078	$ 14,569
Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	402
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	28,549
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	0
Commercial Real Estate | Construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
Commercial Real Estate | Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	26,703
Commercial Real Estate | Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	1,846
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
Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	3,344
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 | Construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	15
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	2,927
Residential | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	402
Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	17,750
Other | Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	17,450
Other | Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	300
Other | Construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0
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
Collateral Dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	11,863
Collateral Dependent | Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	4,985
Collateral Dependent | Agricultural land, production and other loans to farmers
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	0
Collateral Dependent | Construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	1
Collateral Dependent | Commercial real estate, non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	6,463
Collateral Dependent | Commercial real estate, owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	21
Collateral Dependent | Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	327
Collateral Dependent | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance on Collateral Dependent Loans	$ 66

[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.