Loans (Loans Individually Evaluated for Impairment by Class of Loans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$ 14,336	[1]		$ 15,052
Recorded Investment	12,344			12,663
Allowance for Loan Losses Allocated	5,054			5,411
Average Recorded Investment	13,044		16,329
Interest Income Recognized	55		12
Cash Basis Recognized	23		10
Impaired Financing Receivables with No Related Allowance [Member] | Commercial and Industrial Loans and Leases [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	87	[1]		108
Recorded Investment	84			87
Allowance for Loan Losses Allocated	0			0
Average Recorded Investment	110		655
Interest Income Recognized	0		1
Cash Basis Recognized	1		1
Impaired Financing Receivables with No Related Allowance [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,552	[1]		4,312
Recorded Investment	1,630			2,154
Allowance for Loan Losses Allocated	0			0
Average Recorded Investment	2,170		5,550
Interest Income Recognized	0		4
Cash Basis Recognized	0		4
Impaired Financing Receivables with No Related Allowance [Member] | Agricultural Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	2,397	[1]		2,126
Recorded Investment	2,414			2,137
Allowance for Loan Losses Allocated	0			0
Average Recorded Investment	2,422		0
Interest Income Recognized	48		0
Cash Basis Recognized	16		0
Impaired Financing Receivables with No Related Allowance [Member] | Subtotal [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	6,036	[1]		6,546
Recorded Investment	4,128			4,378
Allowance for Loan Losses Allocated	0			0
Average Recorded Investment	4,702		6,205
Interest Income Recognized	48		5
Cash Basis Recognized	17		5
Impaired Financing Receivables with Related Allowance [Member] | Commercial and Industrial Loans and Leases [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	2,545	[1]		2,642
Recorded Investment	2,480			2,581
Allowance for Loan Losses Allocated	1,076			1,347
Average Recorded Investment	2,533		2,841
Interest Income Recognized	1		1
Cash Basis Recognized	1		1
Impaired Financing Receivables with Related Allowance [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	5,755	[1]		5,579
Recorded Investment	5,736			5,418
Allowance for Loan Losses Allocated	3,978			3,914
Average Recorded Investment	5,809		7,283
Interest Income Recognized	6		6
Cash Basis Recognized	5		4
Impaired Financing Receivables with Related Allowance [Member] | Agricultural Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	[1]		285
Recorded Investment	0			286
Allowance for Loan Losses Allocated	0			150
Average Recorded Investment	0		0
Interest Income Recognized	0		0
Cash Basis Recognized	0		0
Impaired Financing Receivables with Related Allowance [Member] | Subtotal [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	8,300	[1]		8,506
Recorded Investment	8,216			8,285
Allowance for Loan Losses Allocated	5,054			5,411
Average Recorded Investment	8,342		10,124
Interest Income Recognized	7		7
Cash Basis Recognized	6		5
Loans Acquired With Deteriorated Credit Quality With No Related Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	38	[1]		45
Recorded Investment	35			25
Allowance for Loan Losses Allocated	0			0
Average Recorded Investment	57		0
Interest Income Recognized	0		0
Cash Basis Recognized	1		0
Loans Acquired With Deteriorated Credit Quality With Additional Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	146	[1]		155
Recorded Investment	107			118
Allowance for Loan Losses Allocated	80			88
Average Recorded Investment	112		205
Interest Income Recognized	1		0
Cash Basis Recognized	$ 1		$ 0

[1] Unpaid Principal Balance is the remaining contractual payments inclusive of partial charge-offs.