Loans (Risk Category of Loans by Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 3,270,934		$ 3,081,973
Commercial and Industrial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	371,869
2019	103,421
2018	58,031
2017	43,613
2016	27,644
Prior	70,197
Revolving Loans Amortized Cost Basis	120,913
Total	795,688	$ 534,692	589,758
Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	142,163
2019	246,423
2018	225,795
2017	233,624
2016	205,508
Prior	383,621
Revolving Loans Amortized Cost Basis	36,100
Total	1,473,234	1,500,247	1,495,862
Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	32,769
2019	37,221
2018	38,926
2017	45,651
2016	31,261
Prior	94,945
Revolving Loans Amortized Cost Basis	92,710
Total	373,483	384,654	384,526
Leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9,796
2019	21,094
2018	11,110
2017	6,944
2016	2,892
Prior	4,892
Revolving Loans Amortized Cost Basis	0
Total	56,728	$ 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	369,836
2019	103,058
2018	55,284
2017	39,975
2016	26,295
Prior	60,942
Revolving Loans Amortized Cost Basis	110,480
Total	765,870
Pass | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	141,956
2019	243,084
2018	219,374
2017	227,575
2016	202,118
Prior	357,949
Revolving Loans Amortized Cost Basis	35,066
Total	1,427,122		1,453,310
Pass | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	26,853
2019	30,206
2018	36,271
2017	36,205
2016	24,406
Prior	72,472
Revolving Loans Amortized Cost Basis	76,836
Total	303,249		325,991
Pass | Leases
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9,796
2019	21,094
2018	11,110
2017	6,944
2016	2,892
Prior	4,892
Revolving Loans Amortized Cost Basis	0
Total	56,728
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	53
2019	363
2018	1,354
2017	2,211
2016	185
Prior	1,859
Revolving Loans Amortized Cost Basis	2,470
Total	8,495
Special Mention | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	207
2019	2,936
2018	4,209
2017	4,134
2016	2,042
Prior	17,108
Revolving Loans Amortized Cost Basis	1,034
Total	31,670		30,504
Special Mention | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5,318
2019	6,853
2018	2,262
2017	8,137
2016	2,351
Prior	16,228
Revolving Loans Amortized Cost Basis	15,694
Total	56,843		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	1,980
2019	0
2018	1,393
2017	1,427
2016	1,164
Prior	7,396
Revolving Loans Amortized Cost Basis	7,963
Total	21,323
Substandard | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	403
2018	2,212
2017	1,915
2016	1,348
Prior	8,564
Revolving Loans Amortized Cost Basis	0
Total	14,442		16,050
Substandard | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	598
2019	162
2018	393
2017	1,309
2016	4,504
Prior	6,245
Revolving Loans Amortized Cost Basis	180
Total	13,391		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
Total
Financing Receivable, Credit Quality Indicator [Line Items]
Total			2,482,138
Total | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total			1,499,864
Total | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total			$ 390,871