Fair value measurements - Summary of Level 3 financial instruments (Details) - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Fair value measurements
Fair value		$ 178
Fair value of property or collateral \| Residential loan
Fair value measurements
Fair value	$ 82	$ 50
Appraised value, selling cost	7.00%	7.00%
Appraised value, weighted average rate (as a percent)	54.00%
Fair value of property or collateral \| Residential loan \| Minimum
Fair value measurements
Appraised value (as a percent)	42.00%
Fair value of property or collateral \| Residential loan \| Maximum
Fair value measurements
Appraised value (as a percent)	66.00%
Fair value of property or collateral \| Home equity line of credit
Fair value measurements
Fair value		$ 128
Appraised value, selling cost	7.00%	7.00%
Fair value of property or collateral \| Real estate acquired in settlement of loans
Fair value measurements
Fair value	$ 797	$ 1,030
Appraised value, selling cost	7.00%	7.00%
Appraised value (as a percent)	100.00%	100.00%
Appraised value, weighted average rate (as a percent)	100.00%	100.00%

Fair Value Assumptions, Appraised Value, Weighted Average Rate

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- Definition

Fair Value Assumptions, Selling Cost, Percent

+ References

No definition available.

+ Details

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- Definition

Represents the appraised value used as an input to measure fair value, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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