Loans (Schedule of Aging of Recorded Investment in Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Financing Receivable, Past Due [Line Items]
Total	$ 3,095,902	[1]	$ 2,744,042	[2]
Total Past Due	19,974	[1]	21,364	[2]
Loans Not Past Due	3,075,928	[1]	2,722,678	[2]
Accrued interest receivable included in total recorded investment in loans and leases	13,929	[1]	12,301
Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total	591,403	[1]	545,342	[2]
Total Past Due	5,571		5,669
Loans Not Past Due	585,832		539,673
Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total	1,499,864	[1]	1,211,882	[2]
Total Past Due	2,746		4,505
Loans Not Past Due	1,497,118		1,207,377
Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total	390,871	[1]	370,694	[2]
Total Past Due	828		1,642
Loans Not Past Due	390,043		369,052
Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total	226,775	[1]	209,009	[2]
Total Past Due	1,454		656
Loans Not Past Due	225,321		208,353
Consumer Loans
Financing Receivable, Past Due [Line Items]
Total	81,429	[1]	77,761	[2]
Total Past Due	592		1,214
Loans Not Past Due	80,837		76,547
Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total	305,560	[1]	329,354	[2]
Total Past Due	8,783		7,678
Loans Not Past Due	296,777		321,676
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	11,879	[1]	12,958	[2]
30-59 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total Past Due	4,689		5,414
30-59 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	209		768
30-59 Days Past Due | Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	499		563
30-59 Days Past Due | Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	1,121		471
30-59 Days Past Due | Consumer Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	347		971
30-59 Days Past Due | Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	5,014		4,771
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	2,384	[1]	3,432	[2]
60-89 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total Past Due	83		183
60-89 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	431		705
60-89 Days Past Due | Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	0		805
60-89 Days Past Due | Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	253		125
60-89 Days Past Due | Consumer Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	156		94
60-89 Days Past Due | Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	1,461		1,520
90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	5,711	[1]	4,974	[2]
90 Days or More Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total Past Due	799		72
90 Days or More Past Due | Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	2,106		3,032
90 Days or More Past Due | Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	329		274
90 Days or More Past Due | Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	80		60
90 Days or More Past Due | Consumer Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	89		149
90 Days or More Past Due | Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total Past Due	2,308		1,387
Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Total	12,798		11,556		$ 9,117
Total Past Due	1,607		2,592
Loans Not Past Due	11,191		8,964
Loans Acquired with Deteriorated Credit Quality | Commercial and Industrial Loans and Leases
Financing Receivable, Past Due [Line Items]
Total	1,368		1,038		988
Loans Acquired with Deteriorated Credit Quality | Commercial Real Estate Loans
Financing Receivable, Past Due [Line Items]
Total	7,212		6,993		6,452
Loans Acquired with Deteriorated Credit Quality | Agricultural Loans
Financing Receivable, Past Due [Line Items]
Total	3,161		1,877		789
Loans Acquired with Deteriorated Credit Quality | Home Equity Loans
Financing Receivable, Past Due [Line Items]
Total	369		365		0
Loans Acquired with Deteriorated Credit Quality | Consumer Loans
Financing Receivable, Past Due [Line Items]
Total	0		0		0
Loans Acquired with Deteriorated Credit Quality | Residential Mortgage Loans
Financing Receivable, Past Due [Line Items]
Total	688		1,283		$ 888
Loans Acquired with Deteriorated Credit Quality | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	18		448
Loans Acquired with Deteriorated Credit Quality | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0		885
Loans Acquired with Deteriorated Credit Quality | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	1,589		1,259
Loans Acquired with Deteriorated Credit Quality | Loans Acquired in Current Year
Financing Receivable, Past Due [Line Items]
Total	321,464		481,901
Total Past Due	1,437		6,382
Loans Not Past Due	320,027		475,519
Loans Acquired with Deteriorated Credit Quality | Loans Acquired in Current Year | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	639		2,571
Loans Acquired with Deteriorated Credit Quality | Loans Acquired in Current Year | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	1		1,620
Loans Acquired with Deteriorated Credit Quality | Loans Acquired in Current Year | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 797		$ 2,191

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

[2] Total recorded investment in loans includes $12,301 in accrued interest.