Premises and equipment - Schedule of Premises and Equipment and Related Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 136,498	$ 126,880
Less: accumulated depreciation	(49,616)	(45,303)
Total Premises and Equipment	86,882	81,577
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	25,821	22,108
Premises
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	60,995	57,719
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	23,220	22,292
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	11,819	10,740
Equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	13,774	12,525
Construction in process
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 869	$ 1,496

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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