Loans (Aging of Recorded Investment in Past Due Loans by Class of Loans) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	$ 1,250,674	[1]	$ 1,213,423	[2]
30-59 Days Past Due	3,723	[1]	4,508	[2]
60-89 Days Past Due	927	[1]	713	[2]
90 Days or More Past Due	2,675	[1]	2,964	[2]
Total Past Due	7,325	[1]	8,185	[2]
Loans Not Past Due	1,243,349	[1]	1,205,238	[2]
Commercial and Industrial Loans and Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	347,299	[1]	336,307	[2]
30-59 Days Past Due	302		436
60-89 Days Past Due	119		133
90 Days or More Past Due	429		448
Total Past Due	850		1,017
Loans Not Past Due	346,449		335,290
Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	510,013	[1]	489,796	[2]
30-59 Days Past Due	206		1,352
60-89 Days Past Due	40		0
90 Days or More Past Due	1,657		2,063
Total Past Due	1,903		3,415
Loans Not Past Due	508,110		486,381
Agricultural Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	177,962	[1]	182,575	[2]
30-59 Days Past Due	0		42
60-89 Days Past Due	0		14
90 Days or More Past Due	116		0
Total Past Due	116		56
Loans Not Past Due	177,846		182,519
Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	73,486	[1]	74,699	[2]
30-59 Days Past Due	336		177
60-89 Days Past Due	98		48
90 Days or More Past Due	267		178
Total Past Due	701		403
Loans Not Past Due	72,785		74,296
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	46,315	[1]	41,231	[2]
30-59 Days Past Due	207		431
60-89 Days Past Due	27		23
90 Days or More Past Due	53		18
Total Past Due	287		472
Loans Not Past Due	46,028		40,759
Residential Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	95,599	[1]	88,815	[2]
30-59 Days Past Due	2,672		2,070
60-89 Days Past Due	643		495
90 Days or More Past Due	153		257
Total Past Due	3,468		2,822
Loans Not Past Due	92,131		85,993
Loans Acquired With Deteriorated Credit Quality [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	9,851		11,174
30-59 Days Past Due	0		0
60-89 Days Past Due	0		120
90 Days or More Past Due	0		0
Total Past Due	0		120
Loans Not Past Due	$ 9,851		$ 11,054

[1] Total recorded investment in loans includes $4,969 in accrued interest.

[2] Total recorded investment in loans includes $5,522 in accrued interest.