Segment Disclosures - Summary of Disaggregation of Revenue by Source (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 398,502	$ 361,952	$ 853,108	$ 753,674
Financial Services
Disaggregation of Revenue [Line Items]
Revenue	290,930	259,308	634,016	548,054
Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	95,838	91,708	195,892	184,194
National Practices
Disaggregation of Revenue [Line Items]
Revenue	11,734	10,936	23,200	21,426
Accounting, tax, advisory and consulting
Disaggregation of Revenue [Line Items]
Revenue	290,930	259,308	634,016	548,054
Accounting, tax, advisory and consulting | Financial Services
Disaggregation of Revenue [Line Items]
Revenue	290,930	259,308	634,016	548,054
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	91,031	87,366	187,648	176,302
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	91,031	87,366	187,648	176,302
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	4,807	4,342	8,244	7,892
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	4,807	4,342	8,244	7,892
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	9,067	8,333	18,021	16,254
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	9,067	8,333	18,021	16,254
National practices consulting
Disaggregation of Revenue [Line Items]
Revenue	2,667	2,603	5,179	5,172
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	$ 2,667	$ 2,603	$ 5,179	$ 5,172