Loans and Allowance for Loan Losses (Activity in Allowance for Loan Losses by Portfolio Segment) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 23,011	$ 22,293	$ 20,246
Loans charged off	(4,502)	(5,025)	(5,547)
Recoveries	744	1,002	1,269
Provision for loan losses	3,791	4,741	6,325
Ending balance	23,044	23,011	22,293
Ending Balance: Individually evaluated for impairment	3,106	3,671
Ending Balance: Collectively evaluated for impairment	19,938	19,340
Ending Balance: Individually evaluated for impairment	27,157	27,386
Ending Balance: Collectively evaluated for impairment	1,536,709	1,486,642
Loans ending balance	1,563,866	1,514,028
Residential real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	6,398	3,273
Loans charged off	(1,197)	(1,216)
Recoveries	73	120
Provision for loan losses	1,722	4,221
Ending balance	6,996	6,398
Ending Balance: Individually evaluated for impairment	2,255	1,364
Ending Balance: Collectively evaluated for impairment	4,741	5,034
Ending Balance: Individually evaluated for impairment	13,805	12,715
Ending Balance: Collectively evaluated for impairment	558,368	565,547
Loans ending balance	572,173	578,262
Commercial real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	5,702	8,198
Loans charged off	(593)	(1,633)
Recoveries	222	374
Provision for loan losses	(782)	(1,237)
Ending balance	4,549	5,702
Ending Balance: Individually evaluated for impairment	265	961
Ending Balance: Collectively evaluated for impairment	4,284	4,741
Ending Balance: Individually evaluated for impairment	7,968	7,830
Ending Balance: Collectively evaluated for impairment	498,263	462,231
Loans ending balance	506,231	470,061
Commercial loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	4,846	5,633
Loans charged off	(1,393)	(1,256)
Recoveries	406	296
Provision for loan losses	2,074	173
Ending balance	5,933	4,846
Ending Balance: Individually evaluated for impairment	286	815
Ending Balance: Collectively evaluated for impairment	5,647	4,031
Ending Balance: Individually evaluated for impairment	3,610	4,019
Ending Balance: Collectively evaluated for impairment	186,844	181,026
Loans ending balance	190,454	185,045
Home equity loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,704	2,051
Loans charged off	(1,234)	(861)
Recoveries	23	196
Provision for loan losses	1,027	1,318
Ending balance	2,520	2,704
Ending Balance: Individually evaluated for impairment	261	440
Ending Balance: Collectively evaluated for impairment	2,259	2,264
Ending Balance: Individually evaluated for impairment	1,515	2,670
Ending Balance: Collectively evaluated for impairment	276,860	266,112
Loans ending balance	278,375	268,782
Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	420	202
Loans charged off	(85)	(59)
Recoveries	20	16
Provision for loan losses	(171)	261
Ending balance	184	420
Ending Balance: Individually evaluated for impairment	39	91
Ending Balance: Collectively evaluated for impairment	145	329
Ending Balance: Individually evaluated for impairment	259	152
Ending Balance: Collectively evaluated for impairment	16,374	11,726
Loans ending balance	16,633	11,878
Unallocated
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,941	2,936
Loans charged off
Recoveries
Provision for loan losses	(79)	5
Ending balance	2,862	2,941
Ending Balance: Individually evaluated for impairment
Ending Balance: Collectively evaluated for impairment	2,862	2,941
Ending Balance: Individually evaluated for impairment
Ending Balance: Collectively evaluated for impairment
Loans ending balance