Servicing rights - Assumptions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
SBA servicing rights
Adverse changes to key assumptions on the carrying amount of the servicing rights
Prepayment rate (10% adverse change)	$ (543)	$ (578)
Prepayment rate (20% adverse change)	(1,069)	(1,125)
Default rate (10% adverse change)	(165)	(125)
Default rate (20% adverse change)	(328)	(249)
Discount rate (10% adverse change)	(1,530)	(861)
Discount rate (20% adverse change)	(2,922)	(1,642)
Cost of servicing (10% adverse change)	(2,047)	(1,228)
Cost of servicing (20% adverse change)	(4,095)	(2,455)
Multi-family servicing rights
Adverse changes to key assumptions on the carrying amount of the servicing rights
Prepayment rate (10% adverse change)	(491)	(271)
Prepayment rate (20% adverse change)	(965)	(537)
Default rate (10% adverse change)	(14)	(22)
Default rate (20% adverse change)	(29)	(44)
Discount rate (10% adverse change)	(2,320)	(2,057)
Discount rate (20% adverse change)	(4,524)	(4,012)
Cost of servicing (10% adverse change)	(2,587)	(2,685)
Cost of servicing (20% adverse change)	$ (5,173)	$ (5,370)