Loans (Schedule of Risk Category of Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2019		Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 2,732,452	[1]	$ 2,744,042	[2]
Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	10,029		11,556
Loans Acquired With Deteriorated Credit Quality | Loans Acquired in Current Year
Financing Receivable, Credit Quality Indicator [Line Items]
Total			481,901
Commercial and Industrial Loans and Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Total	555,935	[1]	545,342	[2]
Commercial and Industrial Loans and Leases | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	882		1,038
Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,216,906	[1]	1,211,882	[2]
Commercial Real Estate Loans | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	5,629		6,993
Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	368,912	[1]	370,694	[2]
Agricultural Loans | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,882		1,877
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,028,055		1,996,743
Pass | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	230		0
Pass | Loans Acquired With Deteriorated Credit Quality | Loans Acquired in Current Year
Financing Receivable, Credit Quality Indicator [Line Items]
Total			250,415
Pass | Commercial and Industrial Loans and Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Total	536,263		517,497
Pass | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,182,369		1,165,937
Pass | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	309,423		313,309
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	75,086		75,247
Special Mention | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,435		1,436
Special Mention | Loans Acquired With Deteriorated Credit Quality | Loans Acquired in Current Year
Financing Receivable, Credit Quality Indicator [Line Items]
Total			14,972
Special Mention | Commercial and Industrial Loans and Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Total	5,745		7,541
Special Mention | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	22,329		26,723
Special Mention | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	47,012		40,983
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	38,612		55,928
Substandard | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,728		8,472
Substandard | Loans Acquired With Deteriorated Credit Quality | Loans Acquired in Current Year
Financing Receivable, Credit Quality Indicator [Line Items]
Total			11,521
Substandard | Commercial and Industrial Loans and Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Total	13,927		20,304
Substandard | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	12,208		19,222
Substandard | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	12,477		16,402
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Doubtful | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Doubtful | Loans Acquired With Deteriorated Credit Quality | Loans Acquired in Current Year
Financing Receivable, Credit Quality Indicator [Line Items]
Total			0
Doubtful | Commercial and Industrial Loans and Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Doubtful | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Doubtful | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Total
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,141,753		2,127,918
Total | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,393		9,908
Total | Loans Acquired With Deteriorated Credit Quality | Loans Acquired in Current Year
Financing Receivable, Credit Quality Indicator [Line Items]
Total			276,908
Total | Commercial and Industrial Loans and Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Total	555,935		545,342
Total | Commercial Real Estate Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,216,906		1,211,882
Total | Agricultural Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 368,912		$ 370,694

[1] Total recorded investment in loans includes $11,778 in accrued interest.

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