Loans and Allowance - Credit Quality of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 9,243,174	$ 8,459,310
Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,776,699	2,109,879
Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	281,884	334,172
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	484,723	787,568
Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,220,949	1,902,692
Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	958,501	909,695
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,234,741	1,143,217
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	508,259	588,984
Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	129,479	135,989
Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	647,939	547,114
Commercial Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	7,000,298	6,447,193
Commercial Pass | Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,562,077	1,956,985
Commercial Pass | Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	243,991	291,790
Commercial Pass | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	446,846	749,249
Commercial Pass | Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,979,827	1,814,187
Commercial Pass | Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	907,566	866,947
Commercial Pass | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	199,338	196,710
Commercial Pass | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	12,714	24,211
Commercial Pass | Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Pass | Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	647,939	547,114
Commercial Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	334,989	147,328
Commercial Special Mention | Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	117,503	81,179
Commercial Special Mention | Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	26,835	11,008
Commercial Special Mention | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	10,445	1,613
Commercial Special Mention | Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	160,304	38,366
Commercial Special Mention | Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	17,641	14,028
Commercial Special Mention | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,261	877
Commercial Special Mention | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	257
Commercial Special Mention | Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Special Mention | Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	234,712	190,358
Commercial Substandard | Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	97,119	71,715
Commercial Substandard | Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	9,885	29,393
Commercial Substandard | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	5,549	1,634
Commercial Substandard | Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	80,818	50,139
Commercial Substandard | Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	33,294	28,720
Commercial Substandard | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	7,058	8,075
Commercial Substandard | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	989	682
Commercial Substandard | Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Substandard | Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Doubtful | Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Commercial Loss | Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,666,062	1,668,247
Consumer Performing | Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Performing | Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,173	1,981
Consumer Performing | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	21,763	35,072
Consumer Performing | Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Performing | Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Performing | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,020,687	932,743
Consumer Performing | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	492,999	562,507
Consumer Performing | Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	129,440	135,944
Consumer Performing | Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Non Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	7,113	6,184
Consumer Non Performing | Commercial and industrial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Non Performing | Agricultural land, production and other loans to farmers
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Non Performing | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	120	0
Consumer Non Performing | Commercial real estate, non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Non Performing | Commercial real estate, owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0	0
Consumer Non Performing | Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	5,397	4,812
Consumer Non Performing | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,557	1,327
Consumer Non Performing | Individuals' loans for household and other personal expenditures
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	39	45
Consumer Non Performing | Public finance and other commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 0	$ 0