Segment Disclosures - Summary of Disaggregation of Revenue by Source (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 363,262	$ 282,719	$ 1,116,936	$ 862,097
Financial Services
Disaggregation of Revenue [Line Items]
Revenue	259,998	187,232	808,052	577,970
Benefits and Insurance Services
Disaggregation of Revenue [Line Items]
Revenue	92,067	85,797	276,261	255,656
National Practices
Disaggregation of Revenue [Line Items]
Revenue	11,197	9,690	32,623	28,471
Accounting, tax, advisory and consulting
Disaggregation of Revenue [Line Items]
Revenue	259,998	187,232	808,052	577,970
Accounting, tax, advisory and consulting | Financial Services
Disaggregation of Revenue [Line Items]
Revenue	259,998	187,232	808,052	577,970
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	88,364	83,009	264,666	246,367
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	88,364	83,009	264,666	246,367
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	3,703	2,788	11,595	9,289
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	3,703	2,788	11,595	9,289
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	8,514	7,088	24,768	20,952
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	8,514	7,088	24,768	20,952
National practices consulting
Disaggregation of Revenue [Line Items]
Revenue	2,683	2,602	7,855	7,519
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	$ 2,683	$ 2,602	$ 7,855	$ 7,519