Mergers and acquisitions - Schedule of Purchased Credit Deteriorated Credit Quality (Details) $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deterioration credit quality since origination, percentage	10.10%
Allowance for credit loss, purchased with credit deterioration	$ 669
Farmers National
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal balance	18,964
Allowance for credit losses at acquisition	(669)
Net premium attributable to other factors	(63)
Loans purchased credit-deteriorated fair value	18,358
Allowance for credit loss, purchased with credit deterioration	$ 2,885

Financing Receivable, Deterioration Credit Quality Since Origination

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+ References

No definition available.

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- Definition

Amount of increase in allowance for credit loss on financing receivable purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

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- Definition

Amount of allowance for credit loss at acquisition date of financing receivable purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447

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- Definition

Amount at par value of financing receivable purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447

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- Definition

Amount at purchase price of financing receivable purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447

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- Definition

Amount of discount (premium) attributable to other factors on financing receivable purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447

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