Fair value measurement - Assets measured at fair value on nonrecurring basis (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Fair Value
Other real estate	$ 92,137		$ 85,077
ROU assets	126,080		$ 141,748
Nonrecurring
Fair Value
Loans	6,694	$ 19,369
Loans held-for-sale		8,700
Other real estate	2,161	7,942
Long-lived asset held-for-sale		2,728
Total assets measured at fair value on a nonrecurring basis	8,855	38,739
Loans - write-down	(1,183)	(2,957)
Loans held-for-sale - write-down		(596)
Other real estate owned - write down	(769)	(1,503)
Long-lived asset held-for-sale - write down		(303)
Total assets measured - write down	(1,952)	(5,359)
Nonrecurring | Level 1
Fair Value
Loans	0	0
Loans held-for-sale		0
Other real estate	0	0
Long-lived asset held-for-sale		0
Total assets measured at fair value on a nonrecurring basis	0	0
Nonrecurring | Level 2
Fair Value
Loans	0	0
Loans held-for-sale		0
Other real estate	0	0
Long-lived asset held-for-sale		0
Total assets measured at fair value on a nonrecurring basis	0	0
Nonrecurring | Level 3
Fair Value
Loans	6,694	19,369
Loans held-for-sale		8,700
Other real estate	2,161	7,942
Long-lived asset held-for-sale		2,728
Total assets measured at fair value on a nonrecurring basis	$ 8,855	$ 38,739