Loans (Aging of the Recorded Investment in Past Due Loans) (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Total	[1]		$ 3,095,902
Total Past Due		$ 15,329	19,974	[1]
Loans Not Past Due		3,209,903	3,075,928	[1]
Accrued interest included in recorded investment		14,995	13,929
Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			12,798
Total Past Due			1,607
Loans Not Past Due			11,191
Acquired with Deteriorated Credit Quality | Loans Acquired In Current Year
Financing Receivable, Past Due [Line Items]
Total			321,464
Total Past Due			1,437
Loans Not Past Due			320,027
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		5,760	11,879	[1]
30-59 Days Past Due | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total Past Due			18
30-59 Days Past Due | Acquired with Deteriorated Credit Quality | Loans Acquired In Current Year
Financing Receivable, Past Due [Line Items]
Total Past Due			639
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		2,888	2,384	[1]
60-89 Days Past Due | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total Past Due			0
60-89 Days Past Due | Acquired with Deteriorated Credit Quality | Loans Acquired In Current Year
Financing Receivable, Past Due [Line Items]
Total Past Due			1
Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		6,681	5,711	[1]
Greater Than 89 Days Past Due | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total Past Due			1,589
Greater Than 89 Days Past Due | Acquired with Deteriorated Credit Quality | Loans Acquired In Current Year
Financing Receivable, Past Due [Line Items]
Total Past Due			797
Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total	[1]		591,403
Total Past Due			5,571
Loans Not Past Due			585,832
Commercial and Industrial Loans and Leases | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			1,368
Commercial and Industrial Loans and Leases | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due			4,689
Commercial and Industrial Loans and Leases | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due			83
Commercial and Industrial Loans and Leases | Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due			799
Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		1,499,864
Total Past Due		2,595	2,746
Loans Not Past Due		1,450,685	1,497,118
Commercial Real Estate Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			7,212
Commercial Real Estate Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		1,637	209
Commercial Real Estate Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		0	431
Commercial Real Estate Loans | Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		958	2,106
Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		390,871
Total Past Due		651	828
Loans Not Past Due		375,564	390,043
Agricultural Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			3,161
Agricultural Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		0	499
Agricultural Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		578	0
Agricultural Loans | Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		73	329
Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		226,775
Total Past Due		714	1,454
Loans Not Past Due		217,926	225,321
Home Equity Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			369
Home Equity Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		401	1,121
Home Equity Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		113	253
Home Equity Loans | Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		200	80
Consumer Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		81,429
Total Past Due		404	592
Loans Not Past Due		64,515	80,837
Consumer Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			0
Consumer Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		259	347
Consumer Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		61	156
Consumer Loans | Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		84	89
Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		305,560
Total Past Due		6,040	8,783
Loans Not Past Due		256,399	296,777
Residential Mortgage Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			688
Residential Mortgage Loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		3,281	5,014
Residential Mortgage Loans | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		1,947	1,461
Residential Mortgage Loans | Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		$ 812	$ 2,308

[1] Total recorded investment in loans includes $13,929 in accrued interest.