Loans and Allowance for Credit Losses - Composition of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 9,241,861	$ 9,243,174
Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,714,565	2,776,699
Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	246,442	281,884
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	523,066	484,723
Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,135,459	2,220,949
Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	986,720	958,501
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,159,127	1,234,741
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	523,754	508,259
Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	146,092	129,479
Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 806,636	$ 647,939