Income taxes - Current and Deferred Amounts of Provision for Income Taxes Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current									$ 2,761	$ 4,072	$ 6,515
Deferred									394	(681)	1,665
Total income tax expense (benefit)	$ 446	$ 991	$ 957	$ 761	$ 904	$ 902	$ 811	$ 774	3,155	3,391	8,180
Peoples Bank
Total income tax expense (benefit)									$ (1)	$ (27)	$ (54)

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Name:	us-gaap_DeferredIncomeTaxExpenseBenefit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration