Goodwill and intangible assets - Core Deposit and Other Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 62,523	$ 62,523
Accumulated Amortization	(45,570)	(40,097)
Net Carrying Amount	16,953	22,426
Core deposit intangible
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	59,835	59,835
Accumulated Amortization	(43,902)	(38,807)
Net Carrying Amount	15,933	21,028
Customer base trust intangible
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,600	1,600
Accumulated Amortization	(707)	(547)
Net Carrying Amount	893	1,053
Manufactured housing servicing intangible
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,088	1,088
Accumulated Amortization	(961)	(743)
Net Carrying Amount	$ 127	$ 345