Premises and equipment - Premises and Equipment and Related Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Finance lease	$ 1,487	$ 1,588
Premises and equipment and finance lease, gross	212,623	206,881
Less: accumulated depreciation and amortization	(68,884)	(61,766)
Total Premises and Equipment	143,739	145,115
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	33,151	33,151
Premises
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	109,357	108,579
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	25,611	26,729
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	18,531	18,429
Equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	22,781	16,904
Construction in process
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 1,705	$ 1,501