Mortgage Servicing (Additional Information) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Servicing Assets at Fair Value [Line Items]        
Servicing Asset At Amortized Value Net Of Valuation Allowance $ 493,000 $ 726,000    
Servicing Asset at Fair Value, Amount 1,447,000 [1] 1,494,000 [1],[2] 879,000 [1] 1,138,000 [1]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate 4.77%      
Mortgage servicing fee income 251,000 679,000 320,000  
Gain (Loss) on Sale of Mortgage Loans 31,000 728,000 268,000  
Freddie Mac [Member]        
Servicing Assets at Fair Value [Line Items]        
Mortgage loans serviced during period, value 141,100,000 157,900,000 156,100,000  
Custodial escrow balances 484,000 518,000    
Maine State Housing Authority [Member]        
Servicing Assets at Fair Value [Line Items]        
Mortgage servicing fee income 1,200,000 1,100,000 1,200,000  
Mortgage loans serviced during period, value 585,300,000 614,400,000 650,600,000  
Custodial escrow balances 5,300,000 5,300,000    
Fixed Rate Residential Mortgage [Member]        
Servicing Assets at Fair Value [Line Items]        
Mortgage Loans on Real Estate, Cost of Mortgages Sold $ 799,000 $ 33,300,000 $ 16,900,000  
US Treasury Notes Securities [Member]        
Servicing Assets at Fair Value [Line Items]        
term to maturity 10 years      
[1] Reported fair value represents all MSRs currently being serviced by the Company, regardless of carrying amount.
[2] Reported fair value represents all MSRs currently being serviced by the Company at December 31, 2013, regardless of carrying amount.