Loans and Allowance - Past Due Aging of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	$ 183	$ 746
Loans	9,121,250	9,243,174
Commercial and industrial loans
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	594
Loans	2,671,076	2,776,699
Agricultural land, production and other loans to farmers
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	0
Loans	235,020	281,884
Construction
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	0
Loans	491,200	484,723
Commercial real estate, non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	0
Loans	2,263,497	2,220,949
Commercial real estate, owner occupied
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	0
Loans	953,501	958,501
Residential
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	183	133
Loans	1,127,442	1,234,741
Home equity
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	19
Loans	489,997	508,259
Individuals' loans for household and other personal expenditures
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	0
Loans	130,819	129,479
Public finance and other commercial loans
Financing Receivable, Past Due [Line Items]
Loans > 90 Days or More Past Due And Accruing	0	0
Loans	758,698	647,939
Current
Financing Receivable, Past Due [Line Items]
Loans	9,052,818	9,170,399
Current | Commercial and industrial loans
Financing Receivable, Past Due [Line Items]
Loans	2,658,952	2,761,473
Current | Agricultural land, production and other loans to farmers
Financing Receivable, Past Due [Line Items]
Loans	234,432	280,615
Current | Construction
Financing Receivable, Past Due [Line Items]
Loans	491,200	484,706
Current | Commercial real estate, non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	2,221,577	2,184,681
Current | Commercial real estate, owner occupied
Financing Receivable, Past Due [Line Items]
Loans	949,949	951,561
Current | Residential
Financing Receivable, Past Due [Line Items]
Loans	1,121,721	1,226,779
Current | Home equity
Financing Receivable, Past Due [Line Items]
Loans	487,075	503,596
Current | Individuals' loans for household and other personal expenditures
Financing Receivable, Past Due [Line Items]
Loans	129,214	129,049
Current | Public finance and other commercial loans
Financing Receivable, Past Due [Line Items]
Loans	758,698	647,939
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	13,007	19,638
30-59 Days Past Due | Commercial and industrial loans
Financing Receivable, Past Due [Line Items]
Loans	6,336	5,866
30-59 Days Past Due | Agricultural land, production and other loans to farmers
Financing Receivable, Past Due [Line Items]
Loans	0	146
30-59 Days Past Due | Construction
Financing Receivable, Past Due [Line Items]
Loans	0	0
30-59 Days Past Due | Commercial real estate, non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	39	2,525
30-59 Days Past Due | Commercial real estate, owner occupied
Financing Receivable, Past Due [Line Items]
Loans	2,127	4,854
30-59 Days Past Due | Residential
Financing Receivable, Past Due [Line Items]
Loans	2,276	3,269
30-59 Days Past Due | Home equity
Financing Receivable, Past Due [Line Items]
Loans	832	2,644
30-59 Days Past Due | Individuals' loans for household and other personal expenditures
Financing Receivable, Past Due [Line Items]
Loans	1,397	334
30-59 Days Past Due | Public finance and other commercial loans
Financing Receivable, Past Due [Line Items]
Loans	0	0
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	11,634	11,187
60-89 Days Past Due | Commercial and industrial loans
Financing Receivable, Past Due [Line Items]
Loans	4,590	6,571
60-89 Days Past Due | Agricultural land, production and other loans to farmers
Financing Receivable, Past Due [Line Items]
Loans	0	226
60-89 Days Past Due | Construction
Financing Receivable, Past Due [Line Items]
Loans	0	17
60-89 Days Past Due | Commercial real estate, non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	5,364	2,109
60-89 Days Past Due | Commercial real estate, owner occupied
Financing Receivable, Past Due [Line Items]
Loans	0	180
60-89 Days Past Due | Residential
Financing Receivable, Past Due [Line Items]
Loans	347	1,429
60-89 Days Past Due | Home equity
Financing Receivable, Past Due [Line Items]
Loans	1,125	559
60-89 Days Past Due | Individuals' loans for household and other personal expenditures
Financing Receivable, Past Due [Line Items]
Loans	208	96
60-89 Days Past Due | Public finance and other commercial loans
Financing Receivable, Past Due [Line Items]
Loans	0	0
90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	43,791	41,950
90 Days or More Past Due | Commercial and industrial loans
Financing Receivable, Past Due [Line Items]
Loans	1,198	2,789
90 Days or More Past Due | Agricultural land, production and other loans to farmers
Financing Receivable, Past Due [Line Items]
Loans	588	897
90 Days or More Past Due | Construction
Financing Receivable, Past Due [Line Items]
Loans	0	0
90 Days or More Past Due | Commercial real estate, non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	36,517	31,634
90 Days or More Past Due | Commercial real estate, owner occupied
Financing Receivable, Past Due [Line Items]
Loans	1,425	1,906
90 Days or More Past Due | Residential
Financing Receivable, Past Due [Line Items]
Loans	3,098	3,264
90 Days or More Past Due | Home equity
Financing Receivable, Past Due [Line Items]
Loans	965	1,460
90 Days or More Past Due | Individuals' loans for household and other personal expenditures
Financing Receivable, Past Due [Line Items]
Loans	0	0
90 Days or More Past Due | Public finance and other commercial loans
Financing Receivable, Past Due [Line Items]
Loans	$ 0	$ 0