Loans (Risk Category of Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 3,091,998		$ 3,081,973
Commercial and Industrial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	260,788
2019	89,539
2018	50,720
2017	34,881
2016	21,838
Prior	55,896
Revolving Loans Amortized Cost Basis	125,111
Total	638,773	$ 534,692	589,758
Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	297,148
2019	225,718
2018	196,096
2017	208,884
2016	182,886
Prior	326,784
Revolving Loans Amortized Cost Basis	29,881
Total	1,467,397	1,500,247	1,495,862
Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	61,323
2019	35,433
2018	34,790
2017	42,363
2016	29,875
Prior	80,213
Revolving Loans Amortized Cost Basis	92,189
Total	376,186	384,654	384,526
Leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	18,258
2019	17,517
2018	9,176
2017	5,415
2016	1,605
Prior	3,693
Revolving Loans Amortized Cost Basis	0
Total	55,664	$ 57,257
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total			2,336,007
Pass | Commercial and Industrial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	260,027
2019	88,273
2018	46,681
2017	31,612
2016	21,025
Prior	48,508
Revolving Loans Amortized Cost Basis	109,228
Total	605,354
Pass | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	296,265
2019	215,226
2018	179,129
2017	183,703
2016	171,016
Prior	295,641
Revolving Loans Amortized Cost Basis	29,634
Total	1,370,614		1,453,310
Pass | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	49,242
2019	25,449
2018	31,285
2017	32,368
2016	22,702
Prior	64,890
Revolving Loans Amortized Cost Basis	75,871
Total	301,807		325,991
Pass | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	18,258
2019	17,517
2018	9,176
2017	5,415
2016	1,605
Prior	3,693
Revolving Loans Amortized Cost Basis	0
Total	55,664
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total			99,228
Special Mention | Commercial and Industrial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	618
2019	1,102
2018	2,756
2017	1,739
2016	206
Prior	1,972
Revolving Loans Amortized Cost Basis	9,948
Total	18,341
Special Mention | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	883
2019	9,361
2018	15,232
2017	23,489
2016	7,578
Prior	20,294
Revolving Loans Amortized Cost Basis	147
Total	76,984		30,504
Special Mention | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	11,503
2019	9,911
2018	3,111
2017	8,767
2016	2,707
Prior	10,125
Revolving Loans Amortized Cost Basis	16,318
Total	62,442		49,053
Special Mention | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Total	0
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total			46,903
Substandard | Commercial and Industrial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	143
2019	164
2018	1,283
2017	1,530
2016	607
Prior	5,416
Revolving Loans Amortized Cost Basis	5,935
Total	15,078
Substandard | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1,131
2018	1,735
2017	1,692
2016	4,292
Prior	10,849
Revolving Loans Amortized Cost Basis	100
Total	19,799		16,050
Substandard | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	578
2019	73
2018	394
2017	1,228
2016	4,466
Prior	5,198
Revolving Loans Amortized Cost Basis	0
Total	11,937		15,827
Substandard | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Total	0
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total			0
Doubtful | Commercial and Industrial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Total	0
Doubtful | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Total	0		0
Doubtful | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Total	0		$ 0
Doubtful | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Total	$ 0