Loans (Schedule of Risk Category of Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2018		Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 2,163,545	[1]	$ 2,154,502	[2]
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	8,819		9,117
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	1,677,332		1,660,271
Pass | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	2,395		2,604
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	52,033		53,226
Special Mention | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	1,652		1,647
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	38,461		41,402
Substandard | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	3,894		3,978
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Doubtful | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	1,767,826		1,754,899
Total | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	7,941		8,229
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	483,512	[1]	488,058	[2]
Commercial and Industrial Loans and Leases | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	790		988
Commercial and Industrial Loans and Leases | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	459,442		462,212
Commercial and Industrial Loans and Leases | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	7,953		7,901
Commercial and Industrial Loans and Leases | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	16,117		17,945
Commercial and Industrial Loans and Leases | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Commercial and Industrial Loans and Leases | Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	483,512		488,058
Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	950,326	[1]	929,040	[2]
Commercial Real Estate Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	6,194		6,452
Commercial Real Estate Loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	917,878		894,027
Commercial Real Estate Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	16,163		18,037
Commercial Real Estate Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	16,285		16,976
Commercial Real Estate Loans | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Commercial Real Estate Loans | Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	950,326		929,040
Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	333,988	[1]	337,801	[2]
Agricultural Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	957		789
Agricultural Loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	300,012		304,032
Agricultural Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	27,917		27,288
Agricultural Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	6,059		6,481
Agricultural Loans | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Agricultural Loans | Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 333,988		$ 337,801

[1] Total recorded investment in loans includes $9,697 in accrued interest.

[2] Total recorded investment in loans includes $9,483 in accrued interest.