SEGMENT INFORMATION - Reconciliation of total segment operating income before income taxes to total consolidated income before income taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Reconciliation of operating profit loss from segment to consolidated
Operating income before income taxes	$ 53,043	$ 6,973
Unrealized (loss) gain on equity securities	16	0
Amortization of intangible assets	(3,576)	(3,667)
Acquisition expenses	(35)	(57)
Litigation accrual	(119)	0
Gross realized losses	0	(52,329)
Gain on debt extinguishment	0	242
Operating Segment
Reconciliation of operating profit loss from segment to consolidated
Operating income before income taxes	56,757	62,784
Operating Segment | Banking and Corporate
Reconciliation of operating profit loss from segment to consolidated
Operating income before income taxes	40,024	45,214
Unrealized (loss) gain on equity securities	16
Amortization of intangible assets	(973)	(1,206)
Acquisition expenses	0	(17)
Litigation accrual	0
Gross realized losses		(52,329)
Gain on debt extinguishment		242
Operating Segment | Employee Benefit Services
Reconciliation of operating profit loss from segment to consolidated
Operating income before income taxes	12,860	12,167
Unrealized (loss) gain on equity securities	0
Amortization of intangible assets	(1,725)	(1,633)
Acquisition expenses	(35)	0
Litigation accrual	0
Gross realized losses		0
Gain on debt extinguishment		0
Operating Segment | Insurance
Reconciliation of operating profit loss from segment to consolidated
Operating income before income taxes	1,031	2,802
Unrealized (loss) gain on equity securities	0
Amortization of intangible assets	(673)	(630)
Acquisition expenses	0	(40)
Litigation accrual	(119)
Gross realized losses		0
Gain on debt extinguishment		0
Operating Segment | Wealth Management
Reconciliation of operating profit loss from segment to consolidated
Operating income before income taxes	2,842	2,601
Unrealized (loss) gain on equity securities	0
Amortization of intangible assets	(205)	(198)
Acquisition expenses	0	0
Litigation accrual	$ 0
Gross realized losses		0
Gain on debt extinguishment		$ 0