Loans (Aging of Recorded Investment in Past Due Loans by Class of Loans) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	$ 1,289,707	[1]	$ 1,213,423	[2]
30-59 Days Past Due	3,753	[1]	4,508	[2]
60-89 Days Past Due	569	[1]	713	[2]
90 Days or More Past Due	2,579	[1]	2,964	[2]
Total Past Due	6,901	[1]	8,185	[2]
Loans Not Past Due	1,282,806	[1]	1,205,238	[2]
Commercial and Industrial Loans and Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	339,597	[1]	336,307	[2]
30-59 Days Past Due	251		436
60-89 Days Past Due	19		133
90 Days or More Past Due	413		448
Total Past Due	683		1,017
Loans Not Past Due	338,914		335,290
Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	531,547	[1]	489,796	[2]
30-59 Days Past Due	561		1,352
60-89 Days Past Due	216		0
90 Days or More Past Due	1,805		2,063
Total Past Due	2,582		3,415
Loans Not Past Due	528,965		486,381
Agricultural Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	188,475	[1]	182,575	[2]
30-59 Days Past Due	1,021		42
60-89 Days Past Due	0		14
90 Days or More Past Due	94		0
Total Past Due	1,115		56
Loans Not Past Due	187,360		182,519
Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	75,278	[1]	74,699	[2]
30-59 Days Past Due	194		177
60-89 Days Past Due	145		48
90 Days or More Past Due	149		178
Total Past Due	488		403
Loans Not Past Due	74,790		74,296
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	46,879	[1]	41,231	[2]
30-59 Days Past Due	127		431
60-89 Days Past Due	26		23
90 Days or More Past Due	50		18
Total Past Due	203		472
Loans Not Past Due	46,676		40,759
Residential Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	107,931	[1]	88,815	[2]
30-59 Days Past Due	1,599		2,070
60-89 Days Past Due	163		495
90 Days or More Past Due	68		257
Total Past Due	1,830		2,822
Loans Not Past Due	106,101		85,993
Loans Acquired With Deteriorated Credit Quality [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Ending Loans Balance	8,909		11,174
30-59 Days Past Due	245		0
60-89 Days Past Due	0		120
90 Days or More Past Due	0		0
Total Past Due	245		120
Loans Not Past Due	$ 8,664		$ 11,054

[1] Total recorded investment in loans includes $5,417 in accrued interest.

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