Related party transactions - Schedule of Loans Analysis to Executive Officers, Certain Management, Bank Directors and Their Affiliates (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Financing Receivable, Related Parties [Roll Forward]
Loans outstanding, beginning balance	$ 30,880
New loans and advances	775
Change in related party status	0
Repayments	(2,738)
Loans outstanding, ending balance	$ 28,917