Mergers and acquisitions - Schedule of Consideration Paid and Allocation of Purchase Price to Net Assets Acquired (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Feb. 14, 2020	Mar. 31, 2020
Consideration:
Goodwill resulting from merger		$ 5,808
Farmers National
Consideration:
Net shares issued (in shares)	954,797
Purchase price per share (dollar per share)	$ 36.7
Value of stock consideration	$ 35,041
Cash consideration paid	15,001
Total purchase price	50,042
Fair value of net assets acquired including identifiable intangible assets	44,234
Goodwill resulting from merger	$ 5,808
Common stock | Farmers National
Consideration:
Net shares issued (in shares)	954,797