Loans and allowance for loan losses - Financial Effect of TDRs (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($) loan	Sep. 30, 2018 USD ($) loan	Sep. 30, 2019 USD ($) loan	Sep. 30, 2018 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of loans \| loan	5	5	7	9
Pre-modification outstanding recorded investment	$ 3,507	$ 198	$ 6,695	$ 1,340
Post-modification outstanding recorded investment	3,507	198	6,695	1,340
Charge offs and specific reserves	$ 106	$ 0	$ 106	$ 0
Consumer and other
Financing Receivable, Modifications [Line Items]
Number of loans \| loan		4
Pre-modification outstanding recorded investment		$ 55
Post-modification outstanding recorded investment		55
Charge offs and specific reserves		$ 0
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of loans \| loan	1		3	2
Pre-modification outstanding recorded investment	$ 16		$ 3,204	$ 887
Post-modification outstanding recorded investment	16		3,204	887
Charge offs and specific reserves	$ 0		$ 0	$ 0
Construction
Financing Receivable, Modifications [Line Items]
Number of loans \| loan	1		1
Pre-modification outstanding recorded investment	$ 1,070		$ 1,070
Post-modification outstanding recorded investment	1,070		1,070
Charge offs and specific reserves	$ 0		$ 0
Commercial real estate: \| Owner occupied
Financing Receivable, Modifications [Line Items]
Number of loans \| loan	1	1	1	1
Pre-modification outstanding recorded investment	$ 927	$ 143	$ 927	$ 143
Post-modification outstanding recorded investment	927	143	927	143
Charge offs and specific reserves	$ 0	$ 0	$ 0	$ 0
Commercial real estate: \| Non-owner occupied
Financing Receivable, Modifications [Line Items]
Number of loans \| loan	1		1
Pre-modification outstanding recorded investment	$ 1,366		$ 1,366
Post-modification outstanding recorded investment	1,366		1,366
Charge offs and specific reserves	$ 106		$ 106
Residential real estate: \| 1-to-4 family mortgage
Financing Receivable, Modifications [Line Items]
Number of loans \| loan	1		1	1
Pre-modification outstanding recorded investment	$ 128		$ 128	$ 249
Post-modification outstanding recorded investment	128		128	249
Charge offs and specific reserves	$ 0		$ 0	$ 0
Residential real estate: \| Consumer and other
Financing Receivable, Modifications [Line Items]
Number of loans \| loan				5
Pre-modification outstanding recorded investment				$ 61
Post-modification outstanding recorded investment				61
Charge offs and specific reserves				$ 0

Financing receivable modifications charge offs and specific reserves.

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+ References

No definition available.

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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