Loans and Allowance for Loan Losses (Activity in Allowance for Loan Losses by Portfolio Segment) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning balance $ 21,590,000 $ 23,044,000 $ 23,011,000
Loans charged off (3,444,000) (4,274,000) (4,502,000)
Recoveries 746,000 768,000 744,000
Provision (credit) 2,224,000 2,052,000 3,791,000
Ending balance 21,116,000 21,590,000 23,044,000
Ending Balance: Individually evaluated for impairment 2,239,000 2,981,000 3,106,000
Ending Balance: Collectively evaluated for impairment 18,877,000 18,609,000 19,938,000
Ending Balance: Individually evaluated for impairment 21,179,000 27,947,000 27,157,000
Ending Balance: Collectively evaluated for impairment 1,751,431,000 1,552,455,000 1,536,709,000
Total ending loans balance 1,772,610,000 1,580,402,000 1,563,866,000
Residential real estate loans      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning balance 5,603,000 6,996,000 6,398,000
Loans charged off (785,000) (1,059,000) (1,197,000)
Recoveries 165,000 35,000 73,000
Provision (credit) (84,000) (369,000) 1,722,000
Ending balance 4,899,000 5,603,000 6,996,000
Ending Balance: Individually evaluated for impairment 1,220,000 1,750,000 2,255,000
Ending Balance: Collectively evaluated for impairment 3,679,000 3,853,000 4,741,000
Ending Balance: Individually evaluated for impairment 9,656,000 14,435,000 13,805,000
Ending Balance: Collectively evaluated for impairment 575,812,000 555,384,000 558,368,000
Total ending loans balance 585,468,000 569,819,000 572,173,000
Commercial real estate loans      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning balance 4,374,000 4,549,000 5,702,000
Loans charged off (361,000) (952,000) (593,000)
Recoveries 135,000 121,000 222,000
Provision (credit) 334,000 656,000 782,000
Ending balance 4,482,000 4,374,000 4,549,000
Ending Balance: Individually evaluated for impairment 251,000 526,000 265,000
Ending Balance: Collectively evaluated for impairment 4,231,000 3,848,000 4,284,000
Ending Balance: Individually evaluated for impairment 7,658,000 8,864,000 7,968,000
Ending Balance: Collectively evaluated for impairment 633,003,000 532,235,000 498,263,000
Total ending loans balance 640,661,000 541,099,000 506,231,000
Commercial loans      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning balance 6,220,000 5,933,000 4,846,000
Loans charged off (1,544,000) (1,426,000) (1,393,000)
Recoveries 395,000 495,000 406,000
Provision (credit) 1,752,000 1,218,000 2,074,000
Ending balance 6,823,000 6,220,000 5,933,000
Ending Balance: Individually evaluated for impairment 168,000 132,000 286,000
Ending Balance: Collectively evaluated for impairment 6,655,000 6,088,000 5,647,000
Ending Balance: Individually evaluated for impairment 1,853,000 2,635,000 3,610,000
Ending Balance: Collectively evaluated for impairment 255,662,000 176,568,000 186,844,000
Total ending loans balance 257,515,000 179,203,000 190,454,000
Home equity loans      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning balance 2,403,000 2,520,000 2,704,000
Loans charged off (611,000) (647,000) (1,234,000)
Recoveries 19,000 56,000 23,000
Provision (credit) 436,000 474,000 1,027,000
Ending balance 2,247,000 2,403,000 2,520,000
Ending Balance: Individually evaluated for impairment 496,000 433,000 261,000
Ending Balance: Collectively evaluated for impairment 1,751,000 1,970,000 2,259,000
Ending Balance: Individually evaluated for impairment 1,741,000 1,571,000 1,515,000
Ending Balance: Collectively evaluated for impairment 269,968,000 271,059,000 276,860,000
Total ending loans balance 271,709,000 272,630,000 278,375,000
Consumer loans      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning balance 319,000 184,000 420,000
Loans charged off (143,000) (190,000) (85,000)
Recoveries 32,000 61,000 20,000
Provision (credit) 73,000 264,000 171,000
Ending balance 281,000 319,000 184,000
Ending Balance: Individually evaluated for impairment 104,000 140,000 39,000
Ending Balance: Collectively evaluated for impairment 177,000 179,000 145,000
Ending Balance: Individually evaluated for impairment 271,000 442,000 259,000
Ending Balance: Collectively evaluated for impairment 16,986,000 17,209,000 16,374,000
Total ending loans balance 17,257,000 17,651,000 16,633,000
Unallocated      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning balance 2,671,000 2,862,000 2,941,000
Provision (credit) (287,000) (191,000) 79,000
Ending balance 2,384,000 2,671,000 2,862,000
Ending Balance: Collectively evaluated for impairment $ 2,384,000 $ 2,671,000 $ 2,862,000