Bank segment - Allowance for credit losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Allowance for credit losses:
Beginning balance	$ 72,216	$ 71,130
Charge-offs	(3,422)	(1,558)
Recoveries	1,327	1,402
Provision for credit losses	1,175	(3,763)
Ending balance	71,296	67,211
Real estate | Residential 1-4 family
Allowance for credit losses:
Beginning balance	6,270	6,545
Charge-offs	(809)	0
Recoveries	4	8
Provision for credit losses	(853)	1,321
Ending balance	4,612	7,874
Real estate | Commercial real estate
Allowance for credit losses:
Beginning balance	21,898	24,696
Charge-offs	0	0
Recoveries	0	0
Provision for credit losses	803	(4,520)
Ending balance	22,701	20,176
Real estate | Home equity line of credit
Allowance for credit losses:
Beginning balance	6,125	5,657
Charge-offs	(63)	0
Recoveries	17	11
Provision for credit losses	(26)	(18)
Ending balance	6,053	5,650
Real estate | Residential land
Allowance for credit losses:
Beginning balance	717	646
Charge-offs	0	0
Recoveries	0	5
Provision for credit losses	(97)	46
Ending balance	620	697
Real estate | Commercial construction
Allowance for credit losses:
Beginning balance	1,195	2,186
Charge-offs	0	0
Recoveries	0	0
Provision for credit losses	(460)	154
Ending balance	735	2,340
Real estate | Residential construction
Allowance for credit losses:
Beginning balance	46	18
Charge-offs	0	0
Recoveries	0	0
Provision for credit losses	(18)	13
Ending balance	28	31
Commercial
Allowance for credit losses:
Beginning balance	12,426	15,798
Charge-offs	(227)	(76)
Recoveries	398	353
Provision for credit losses	(661)	(1,761)
Ending balance	11,936	14,314
Consumer
Allowance for credit losses:
Beginning balance	23,539	15,584
Charge-offs	(2,323)	(1,482)
Recoveries	908	1,025
Provision for credit losses	2,487	1,002
Ending balance	$ 24,611	$ 16,129