Fair value measurement - Assets measured at fair value on nonrecurring basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate	$ 89,126	$ 85,077
ROU assets	125,573	141,748
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	11,215	21,167	$ 74,511
Loans held-for-sale			2,738
Other real estate	3,992	7,727	20,123
Other foreclosed assets	13	68	116
ROU assets			446
Leasehold improvements			126
Long-lived asset held-for-sale	1,178	9,007
Trademark		156
Total assets measured at fair value on recurring /nonrecurring basis	16,398	38,125	98,060
Loans - write-down	(2,067)	(3,721)	(15,290)
Loans held-for-sale - write-down			(1,311)
Other real estate owned - write down	(1,026)	(1,579)	(3,325)
Other foreclosed assets - write down	(1)	(33)	(148)
ROU Assets - write down			(15,920)
Leasehold improvements - write down			(2,084)
Long-lived asset held-for-sale - write down	(2,155)	(5,320)
Trademark - write down		(5,404)
Total assets measured - write down	(5,249)	(16,057)	(38,078)
Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	0	0	0
Loans held-for-sale			0
Other real estate	0	0	0
Other foreclosed assets	0	0	0
ROU assets			0
Leasehold improvements			0
Long-lived asset held-for-sale	0	0
Trademark		0
Total assets measured at fair value on recurring /nonrecurring basis	0	0	0
Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	0	0	0
Loans held-for-sale			0
Other real estate	0	0	0
Other foreclosed assets	0	0	0
ROU assets			0
Leasehold improvements			0
Long-lived asset held-for-sale	0	0
Trademark		0
Total assets measured at fair value on recurring /nonrecurring basis	0	0	0
Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	11,215	21,167	74,511
Loans held-for-sale			2,738
Other real estate	3,992	7,727	20,123
Other foreclosed assets	13	68	116
ROU assets			446
Leasehold improvements			126
Long-lived asset held-for-sale	1,178	9,007
Trademark		156
Total assets measured at fair value on recurring /nonrecurring basis	$ 16,398	$ 38,125	$ 98,060