Basis of presentation - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($) branch
Class of Stock [Line Items]
Number of full-service branches | branch	72
Loans processed	$ 314,678
Deferred loans	$ 918,300
Payment deferral period	90 days
Paycheck Protection Program
Class of Stock [Line Items]
Loans processed	$ 314,678