Fair value measurements - Quantitative Information About Level 3 Fair Value Measurements (Details) - Level 3 - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Residential loan \| Sales price
Fair value measurements
Fair value		$ 2,468
Residential loan \| Sales price \| Minimum
Fair value measurements
Appraised value		95.00%
Residential loan \| Sales price \| Maximum
Fair value measurements
Appraised value		100.00%
Residential loan \| Sales price \| Weighted Average
Fair value measurements
Appraised value, weighted average rate		97.00%
Residential loan \| Fair value of property or collateral
Fair value measurements
Fair value	$ 613	$ 287
Selling cost	7.00%	7.00%
Residential loan \| Fair value of property or collateral \| Minimum
Fair value measurements
Appraised value	71.00%	42.00%
Residential loan \| Fair value of property or collateral \| Maximum
Fair value measurements
Appraised value	92.00%	65.00%
Residential loan \| Fair value of property or collateral \| Weighted Average
Fair value measurements
Appraised value, weighted average rate	84.00%	61.00%
Commercial \| Fair value of property or collateral
Fair value measurements
Fair value	$ 2,008
Commercial \| Fair value of property or collateral \| Minimum
Fair value measurements
Appraised value	71.00%
Commercial \| Fair value of property or collateral \| Maximum
Fair value measurements
Appraised value	76.00%
Commercial \| Fair value of property or collateral \| Weighted Average
Fair value measurements
Appraised value, weighted average rate	75.00%
Home equity line of credit \| Fair value of property or collateral
Fair value measurements
Fair value		$ 12
Selling cost		7.00%
Loans
Fair value measurements
Fair value	$ 2,621	$ 2,767
Real estate acquired in settlement of loans \| Fair value of property or collateral
Fair value measurements
Fair value		$ 1,189
Selling cost		7.00%
Appraised value		100.00%
Appraised value, weighted average rate		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

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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.

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