Loans (Aging of the Recorded Investment Past Due Loans) (Details) - USD ($) $ in Thousands		Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Total	[1]		$ 3,095,902
Total Past Due		$ 18,106	19,974	[1]
Loans Not Past Due		3,252,828	3,075,928	[1]
Accrued interest included in recorded investment		14,726	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
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 Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		1,499,864
Total Past Due		1,332	2,746
Loans Not Past Due		1,471,902	1,497,118
Commercial Real Estate Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			7,212
Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		390,871
Total Past Due		3,610	828
Loans Not Past Due		369,873	390,043
Agricultural Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			3,161
Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		226,775
Total Past Due		884	1,454
Loans Not Past Due		215,482	225,321
Home Equity Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			369
Consumer Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		81,429
Total Past Due		710	592
Loans Not Past Due		64,262	80,837
Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total	[1]		305,560
Total Past Due		5,740	8,783
Loans Not Past Due		274,506	296,777
Residential Mortgage Loans | Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total			688
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		5,830	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
30-59 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total Past Due			4,689
30-59 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		169	209
30-59 Days Past Due | Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		927	499
30-59 Days Past Due | Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		539	1,121
30-59 Days Past Due | Consumer Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		608	347
30-59 Days Past Due | Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		3,279	5,014
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		1,905	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
60-89 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total Past Due			83
60-89 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		37	431
60-89 Days Past Due | Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		89	0
60-89 Days Past Due | Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		87	253
60-89 Days Past Due | Consumer Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		11	156
60-89 Days Past Due | Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		1,476	1,461
Greater Than 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due		10,371	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
Greater Than 89 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total Past Due			799
Greater Than 89 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		1,126	2,106
Greater Than 89 Days Past Due | Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		2,594	329
Greater Than 89 Days Past Due | Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		258	80
Greater Than 89 Days Past Due | Consumer Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		91	89
Greater Than 89 Days Past Due | Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total Past Due		$ 985	$ 2,308

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