SEGMENT DISCLOSURES - Schedule of Disaggregation of Revenue by Source (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue	$ 420,012	$ 398,502	$ 914,309	$ 853,108
Financial Services
Disaggregation of Revenue [Line Items]
Revenue	309,233	290,930	681,863	634,016
Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	97,419	95,838	205,827	195,892
National Practices
Disaggregation of Revenue [Line Items]
Revenue	13,360	11,734	26,619	23,200
Accounting, tax, advisory and consulting
Disaggregation of Revenue [Line Items]
Revenue	309,233	290,930	681,863	634,016
Accounting, tax, advisory and consulting \| Financial Services
Disaggregation of Revenue [Line Items]
Revenue	309,233	290,930	681,863	634,016
Accounting, tax, advisory and consulting \| Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Accounting, tax, advisory and consulting \| National Practices
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Core benefits and insurance services
Disaggregation of Revenue [Line Items]
Revenue	93,533	91,031	198,738	187,648
Core benefits and insurance services \| Financial Services
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Core benefits and insurance services \| Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	93,533	91,031	198,738	187,648
Core benefits and insurance services \| National Practices
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Non-core benefits and insurance services
Disaggregation of Revenue [Line Items]
Revenue	3,886	4,807	7,089	8,244
Non-core benefits and insurance services \| Financial Services
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Non-core benefits and insurance services \| Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	3,886	4,807	7,089	8,244
Non-core benefits and insurance services \| National Practices
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Managed networking, hardware services
Disaggregation of Revenue [Line Items]
Revenue	10,250	9,067	20,438	18,021
Managed networking, hardware services \| Financial Services
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Managed networking, hardware services \| Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Managed networking, hardware services \| National Practices
Disaggregation of Revenue [Line Items]
Revenue	10,250	9,067	20,438	18,021
National practices consulting
Disaggregation of Revenue [Line Items]
Revenue	3,110	2,667	6,181	5,179
National practices consulting \| Financial Services
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
National practices consulting \| Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
National practices consulting \| National Practices
Disaggregation of Revenue [Line Items]
Revenue	$ 3,110	$ 2,667	$ 6,181	$ 5,179