Goodwill and other intangible assets - Components of other intangible assets subject to amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets
Gross amount	$ 24,489	$ 39,695
Finite Lived Intangible Assets Accumulated Amortization	10,996	23,393
Finite-Lived Intangible Assets, Net	13,493	16,302
Core deposits
Finite-Lived Intangible Assets
Core deposits - Gross	12,810	12,810
Finite Lived Intangible Assets Accumulated Amortization	8,433	7,473
Finite-Lived Intangible Assets, Net	4,377	5,337
Other customer relationship
Finite-Lived Intangible Assets
Customer relationships - Gross	11,679	26,397
Finite Lived Intangible Assets Accumulated Amortization	2,563	15,684
Finite-Lived Intangible Assets, Net	$ 9,116	10,713
Trademarks
Finite-Lived Intangible Assets
Gross amount		488
Finite Lived Intangible Assets Accumulated Amortization		236
Finite-Lived Intangible Assets, Net		$ 252