Goodwill and other intangible assets - Components of other intangible assets subject to amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 27,096	$ 27,096
Accumulated Amortization	20,325	18,092
Net Carrying Value	6,771	9,004
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	12,810	12,810
Accumulated Amortization	12,275	11,315
Net Carrying Value	535	1,495
Other customer relationship
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	14,286	14,286
Accumulated Amortization	8,050	6,777
Net Carrying Value	$ 6,236	$ 7,509