Segment Disclosures - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Revenue	$ 494,297	$ 454,606
Operating expenses (income)	376,485	341,011
Gross margin	117,812	113,595
Corporate general and administrative expenses	18,711	15,598
Operating income	99,101	97,997
Other income (expense):
Interest expense	(4,511)	(3,641)
Gain on sale of operations, net	0	99
Other income (expense), net	9,424	5,112
Total other income, net	4,913	1,570
Income before income tax expense	104,014	99,567
Financial Services
Segment Reporting Information [Line Items]
Revenue	372,630	343,086
Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	108,408	100,054
National Practices
Segment Reporting Information [Line Items]
Revenue	13,259	11,466
Operating Segments | Financial Services
Segment Reporting Information [Line Items]
Revenue	372,630	343,086
Operating expenses (income)	265,561	244,443
Gross margin	107,069	98,643
Corporate general and administrative expenses	0	0
Operating income	107,069	98,643
Other income (expense):
Interest expense	0	0
Gain on sale of operations, net		99
Other income (expense), net	86	255
Total other income, net	86	354
Income before income tax expense	107,155	98,997
Operating Segments | Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	108,408	100,054
Operating expenses (income)	83,637	76,923
Gross margin	24,771	23,131
Corporate general and administrative expenses	0	0
Operating income	24,771	23,131
Other income (expense):
Interest expense	0	(1)
Gain on sale of operations, net		0
Other income (expense), net	44	177
Total other income, net	44	176
Income before income tax expense	24,815	23,307
Operating Segments | National Practices
Segment Reporting Information [Line Items]
Revenue	13,259	11,466
Operating expenses (income)	11,933	10,583
Gross margin	1,326	883
Corporate general and administrative expenses	0	0
Operating income	1,326	883
Other income (expense):
Interest expense	0	0
Gain on sale of operations, net		0
Other income (expense), net	0	0
Total other income, net	0	0
Income before income tax expense	1,326	883
Corporate and Other
Segment Reporting Information [Line Items]
Revenue	0	0
Operating expenses (income)	15,354	9,062
Gross margin	(15,354)	(9,062)
Corporate general and administrative expenses	18,711	15,598
Operating income	(34,065)	(24,660)
Other income (expense):
Interest expense	(4,511)	(3,640)
Gain on sale of operations, net		0
Other income (expense), net	9,294	4,680
Total other income, net	4,783	1,040
Income before income tax expense	$ (29,282)	$ (23,620)