Bank segment - Allowance for credit losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Allowance for credit losses:
Beginning balance	$ 69,456	$ 78,252	$ 71,130	$ 101,201
Charge-offs	(1,646)	(1,915)	(4,721)	(7,856)
Recoveries	1,282	1,582	4,189	4,566
Provision for credit losses	1,314	(1,975)	(192)	(21,967)
Ending balance	70,406	75,944	70,406	75,944
Real estate | Residential 1-4 family
Allowance for credit losses:
Beginning balance	8,520	5,518	6,545	4,600
Charge-offs	0	(47)	0	(67)
Recoveries	2	5	13	59
Provision for credit losses	(938)	522	1,026	1,406
Ending balance	7,584	5,998	7,584	5,998
Real estate | Commercial real estate
Allowance for credit losses:
Beginning balance	20,900	28,708	24,696	35,607
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	136	(2,750)	(3,660)	(9,649)
Ending balance	21,036	25,958	21,036	25,958
Real estate | Home equity line of credit
Allowance for credit losses:
Beginning balance	6,096	5,335	5,657	6,813
Charge-offs	0	(5)	0	(45)
Recoveries	14	7	56	83
Provision for credit losses	(167)	441	230	(1,073)
Ending balance	5,943	5,778	5,943	5,778
Real estate | Residential land
Allowance for credit losses:
Beginning balance	677	618	646	609
Charge-offs	0	0	0	0
Recoveries	0	35	101	56
Provision for credit losses	12	(19)	(58)	(31)
Ending balance	689	634	689	634
Real estate | Commercial construction
Allowance for credit losses:
Beginning balance	2,634	1,629	2,186	4,149
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	(1,635)	104	(1,187)	(2,416)
Ending balance	999	1,733	999	1,733
Real estate | Residential construction
Allowance for credit losses:
Beginning balance	46	16	18	11
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	3	(3)	31	2
Ending balance	49	13	49	13
Commercial
Allowance for credit losses:
Beginning balance	12,413	20,058	15,798	25,462
Charge-offs	(143)	(266)	(367)	(1,356)
Recoveries	303	417	1,055	1,056
Provision for credit losses	378	(758)	(3,535)	(5,711)
Ending balance	12,951	19,451	12,951	19,451
Consumer
Allowance for credit losses:
Beginning balance	18,170	16,370	15,584	23,950
Charge-offs	(1,503)	(1,597)	(4,354)	(6,388)
Recoveries	963	1,118	2,964	3,312
Provision for credit losses	3,525	488	6,961	(4,495)
Ending balance	$ 21,155	$ 16,379	$ 21,155	$ 16,379