Fair value measurements (Details 4) (Fair Value, Inputs, Level 3, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Residential loan | Fair value of property or collateral
Fair value measurements
Fair value	17,331
Residential loan | Fair value of property or collateral | Minimum
Fair value measurements
Appraised value (as a percent)	13.00%
Residential loan | Fair value of property or collateral | Maximum
Fair value measurements
Appraised value (as a percent)	96.00%
Home equity line of credit | Fair value of property or collateral
Fair value measurements
Fair value	732
Home equity line of credit | Fair value of property or collateral | Minimum
Fair value measurements
Appraised value (as a percent)	25.00%
Home equity line of credit | Fair value of property or collateral | Maximum
Fair value measurements
Appraised value (as a percent)	85.00%
Commercial loans
Fair value measurements
Fair value	3,256
Commercial loan 1 | Fair value of property or collateral
Fair value measurements
Fair value	14
U.S. government agency guarantee (as a percent)	85.00%
Commercial loan 2 | Fair value of property or collateral
Fair value measurements
Fair value	118
Appraised value (as a percent)	73.00%
Commercial loan 3 | Fair value of property or collateral
Fair value measurements
Fair value	222
Insurance proceeds (as a percent)	60.00%
Commercial loan 4 | Fair value of property or collateral
Fair value measurements
Fair value	1,127
Commercial loan 4 | Fair value of property or collateral | Minimum
Fair value measurements
Fair value of business assets (as a percent)	9.00%
Commercial loan 4 | Fair value of property or collateral | Maximum
Fair value measurements
Fair value of business assets (as a percent)	93.00%
Commercial loan 5 | Discounted cash flow
Fair value measurements
Fair value	1,775
Present value of expected future cash flows based on anticipated debt restructuring (as a percent)	59.00%
Discount rate (as a percent)	4.50%
Real estate acquired in settlement of loans | Fair value of property or collateral
Fair value measurements
Fair value	1,235
Real estate acquired in settlement of loans | Fair value of property or collateral | Minimum
Fair value measurements
Appraised value (as a percent)	81.00%
Real estate acquired in settlement of loans | Fair value of property or collateral | Maximum
Fair value measurements
Appraised value (as a percent)	99.00%