Investment securities available for sale (Details) (USD $)
Sep. 30, 2012
Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]    
Par value $ 29,348,000 $ 29,237,000
Amortized cost 33,487,000 30,018,000
Gross unrealized gains 66,000 221,000
Gross unrealized losses (137,000) (76,000)
Estimated fair value 33,416,000 30,163,000
Average yield (in hundredths) 2.46% 1.65%
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]    
Securities in a loss position less than twelve months, fair value 19,430,000 17,579,000
Securities in a loss position less than 12 months, unrealized losses (137,000) (74,000)
Securities in a loss position for more than 12 Months, fair value 0 205,000
Securities in a loss position for more than 12 Months, unrealized losses 0 (2,000)
Total fair value 19,430,000 17,784,000
Total unrealized losses (137,000) (76,000)
US Government Agencies [Member] | More than ten years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 14,500,000 2,000,000
Amortized cost 16,985,000 2,000,000
Gross unrealized gains 31,000 1,000
Gross unrealized losses (62,000) 0
Estimated fair value 16,953,000 2,001,000
Average yield (in hundredths) 2.57% 3.81%
Mortgage-backed securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 2,068,000 19,881,000
Amortized cost 2,177,000 20,632,000
Gross unrealized gains 2,000 220,000
Gross unrealized losses (17,000) (49,000)
Estimated fair value 2,162,000 20,803,000
Average yield (in hundredths) 0.80% 1.83%
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]    
Securities in a loss position less than twelve months, fair value 1,979,000 10,221,000
Securities in a loss position less than 12 months, unrealized losses (17,000) (47,000)
Securities in a loss position for more than 12 Months, fair value 0 205,000
Securities in a loss position for more than 12 Months, unrealized losses 0 (2,000)
Total fair value 1,979,000 10,426,000
Total unrealized losses (17,000) (49,000)
Mortgage-backed securities [Member] | One to five years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value   11,000
Amortized cost   11,000
Gross unrealized gains   0
Gross unrealized losses   0
Estimated fair value   11,000
Average yield (in hundredths)   0.01%
Mortgage-backed securities [Member] | More than ten years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 2,068,000 19,870,000
Amortized cost 2,177,000 20,621,000
Gross unrealized gains 2,000 220,000
Gross unrealized losses (17,000) (49,000)
Estimated fair value 2,162,000 20,792,000
Average yield (in hundredths) 0.80% 1.83%
Other investments [Member] | More than ten years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value   7,356,000
Amortized cost   7,386,000
Gross unrealized gains   0
Gross unrealized losses   (27,000)
Estimated fair value   7,359,000
Average yield (in hundredths)   0.55%
US Treasuries [Member]
   
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]    
Securities in a loss position less than twelve months, fair value 9,132,000 7,358,000
Securities in a loss position less than 12 months, unrealized losses (62,000) (27,000)
Securities in a loss position for more than 12 Months, fair value 0 0
Securities in a loss position for more than 12 Months, unrealized losses 0 0
Total fair value 9,132,000 7,358,000
Total unrealized losses (62,000) (27,000)
US Treasuries [Member] | Five to ten years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 3,000,000  
Amortized cost 2,973,000  
Gross unrealized gains 24,000  
Gross unrealized losses 0  
Estimated fair value 2,997,000  
Average yield (in hundredths) 1.73%  
Municipals [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 9,780,000  
Amortized cost 11,353,000  
Gross unrealized gains 9,000  
Gross unrealized losses (58,000)  
Estimated fair value 11,304,000  
Average yield (in hundredths) 2.81%  
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]    
Securities in a loss position less than twelve months, fair value 8,319,000  
Securities in a loss position less than 12 months, unrealized losses (58,000)  
Securities in a loss position for more than 12 Months, fair value 0  
Securities in a loss position for more than 12 Months, unrealized losses 0  
Total fair value 8,319,000  
Total unrealized losses (58,000)  
Municipals [Member] | One to five years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 1,000,000  
Amortized cost 1,105,000  
Gross unrealized gains 0  
Gross unrealized losses (20,000)  
Estimated fair value 1,085,000  
Average yield (in hundredths) 3.25%  
Municipals [Member] | Five to ten years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 1,500,000  
Amortized cost 1,748,000  
Gross unrealized gains 1,000  
Gross unrealized losses 0  
Estimated fair value 1,749,000  
Average yield (in hundredths) 2.33%  
Municipals [Member] | More than ten years [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Par value 7,280,000  
Amortized cost 8,500,000  
Gross unrealized gains 8,000  
Gross unrealized losses (38,000)  
Estimated fair value $ 8,470,000  
Average yield (in hundredths) 2.86%