Loans and Allowance for Credit Losses - Past Due Aging of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Loans	$ 9,241,861	$ 9,243,174
Loans > 90 Days or More Past Due And Accruing	963	746
Current
Financing Receivable, Past Due [Line Items]
Loans	9,207,113	9,170,399
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	15,006	19,638
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	7,056	11,187
90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	12,686	41,950
Commercial and industrial loans
Financing Receivable, Past Due [Line Items]
Loans	2,714,565	2,776,699
Loans > 90 Days or More Past Due And Accruing	675	594
Commercial and industrial loans | Current
Financing Receivable, Past Due [Line Items]
Loans	2,708,539	2,761,473
Commercial and industrial loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	2,602	5,866
Commercial and industrial loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	2,437	6,571
Commercial and industrial loans | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	987	2,789
Agricultural land, production and other loans to farmers
Financing Receivable, Past Due [Line Items]
Loans	246,442	281,884
Loans > 90 Days or More Past Due And Accruing	0	0
Agricultural land, production and other loans to farmers | Current
Financing Receivable, Past Due [Line Items]
Loans	246,380	280,615
Agricultural land, production and other loans to farmers | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	36	146
Agricultural land, production and other loans to farmers | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	226
Agricultural land, production and other loans to farmers | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	26	897
Construction
Financing Receivable, Past Due [Line Items]
Loans	523,066	484,723
Loans > 90 Days or More Past Due And Accruing	0	0
Construction | Current
Financing Receivable, Past Due [Line Items]
Loans	522,349	484,706
Construction | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	717	0
Construction | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	17
Construction | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	0
Commercial real estate, non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	2,135,459	2,220,949
Loans > 90 Days or More Past Due And Accruing	0	0
Commercial real estate, non-owner occupied | Current
Financing Receivable, Past Due [Line Items]
Loans	2,124,853	2,184,681
Commercial real estate, non-owner occupied | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	3,327	2,525
Commercial real estate, non-owner occupied | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	2,109
Commercial real estate, non-owner occupied | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	7,279	31,634
Commercial real estate, owner occupied
Financing Receivable, Past Due [Line Items]
Loans	986,720	958,501
Loans > 90 Days or More Past Due And Accruing	0	0
Commercial real estate, owner occupied | Current
Financing Receivable, Past Due [Line Items]
Loans	985,785	951,561
Commercial real estate, owner occupied | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	643	4,854
Commercial real estate, owner occupied | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	180
Commercial real estate, owner occupied | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	292	1,906
Residential
Financing Receivable, Past Due [Line Items]
Loans	1,159,127	1,234,741
Loans > 90 Days or More Past Due And Accruing	0	133
Residential | Current
Financing Receivable, Past Due [Line Items]
Loans	1,148,294	1,226,779
Residential | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	3,979	3,269
Residential | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	4,255	1,429
Residential | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	2,599	3,264
Home equity
Financing Receivable, Past Due [Line Items]
Loans	523,754	508,259
Loans > 90 Days or More Past Due And Accruing	288	19
Home equity | Current
Financing Receivable, Past Due [Line Items]
Loans	518,643	503,596
Home equity | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	3,327	2,644
Home equity | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	281	559
Home equity | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	1,503	1,460
Consumer
Financing Receivable, Past Due [Line Items]
Loans	146,092	129,479
Loans > 90 Days or More Past Due And Accruing	0	0
Consumer | Current
Financing Receivable, Past Due [Line Items]
Loans	145,634	129,049
Consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	375	334
Consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	83	96
Consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	0
Public finance and other commercial loans
Financing Receivable, Past Due [Line Items]
Loans	806,636	647,939
Loans > 90 Days or More Past Due And Accruing	0	0
Public finance and other commercial loans | Current
Financing Receivable, Past Due [Line Items]
Loans	806,636	647,939
Public finance and other commercial loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	0
Public finance and other commercial loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans	0	0
Public finance and other commercial loans | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans	$ 0	$ 0