Fair value measurements (Details 4) (Fair Value, Inputs, Level 3, USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Fair value measurements
Fair value	$ 5,058	$ 4,416
Weighted average discount rate	4.50%	4.50%
Residential loan | Fair value of property or collateral
Fair value measurements
Fair value	3,040	2,361
Appraised value, selling cost	7.00%	7.00%
Appraised value, weighted average rate (as a percent)	86.00%	87.00%
Residential loan | Fair value of property or collateral | Minimum
Fair value measurements
Appraised value (as a percent)	60.00%	44.00%
Residential loan | Fair value of property or collateral | Maximum
Fair value measurements
Appraised value (as a percent)	96.00%	96.00%
Home equity line of credit | Fair value of property or collateral
Fair value measurements
Fair value	169	170
Appraised value, selling cost	7.00%	7.00%
Appraised value, weighted average rate (as a percent)	49.00%	50.00%
Home equity line of credit | Fair value of property or collateral | Minimum
Fair value measurements
Appraised value (as a percent)	43.00%	45.00%
Home equity line of credit | Fair value of property or collateral | Maximum
Fair value measurements
Appraised value (as a percent)	50.00%	50.00%
Commercial loans | Fair value of property or collateral
Fair value measurements
Fair value	217	217
Fair value, weighted average rate (as a percent)	19.00%	19.00%
Commercial loan 2 | Discounted Cash Flow [Member]
Fair value measurements
Fair value	$ 1,632	$ 1,668
Fair value, weighted average rate (as a percent)	57.00%	58.00%