Investment securities and impairment of investment securities (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Amortized cost
Total	$ 90,825	$ 103,695
Gross unrealized holding gains
Total	2,164	2,597
Fair value
Total	92,989	106,292
Municipal securities
Amortized cost
Due in five years - ten years	7,425	10,207
Due after ten years	49,131	56,545
Gross unrealized holding gains
Due in five years - ten years	74	141
Due after ten years	998	1,314
Fair value
Due in five years - ten years	7,499	10,348
Due after ten years	50,129	57,859
Residential mortgage-backed securities
Amortized cost
Total	34,269	36,943
Gross unrealized holding gains
Total	1,092	1,142
Fair value
Total	35,361	38,085
Fixed rate | Pass-through
Amortized cost
Total	7,897	8,236
Gross unrealized holding gains
Total	510	477
Fair value
Total	8,407	8,713
Fixed rate | Agency CMOs
Amortized cost
Total	21,239	23,382
Gross unrealized holding gains
Total	481	531
Fair value
Total	21,720	23,913
Variable rate | Pass-through
Amortized cost
Total	4,091	4,273
Gross unrealized holding gains
Total	86	122
Fair value
Total	4,177	4,395
Variable rate | Agency CMOs
Amortized cost
Total	1,042	1,052
Gross unrealized holding gains
Total	15	12
Fair value
Total	$ 1,057	$ 1,064