Segment Disclosures - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Revenue	$ 454,606	$ 391,722
Operating expenses	341,011	290,299
Gross margin	113,595	101,423
Corporate general and administrative expenses	15,598	16,309
Operating income	97,997	85,114
Other income (expense):
Interest expense	(3,641)	(1,259)
Gain on sale of operations, net	99	0
Other income (expense), net	5,112	(6,407)
Total other income (expense), net	1,570	(7,666)
Income before income tax expense	99,567	77,448
Financial Services
Segment Reporting Information [Line Items]
Revenue	343,086	288,746
Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	100,054	92,486
National Practices
Segment Reporting Information [Line Items]
Revenue	11,466	10,490
Operating segments | Financial Services
Segment Reporting Information [Line Items]
Revenue	343,086	288,746
Operating expenses	244,443	209,800
Gross margin	98,643	78,946
Corporate general and administrative expenses	0	0
Operating income	98,643	78,946
Other income (expense):
Interest expense	0	0
Gain on sale of operations, net	99
Other income (expense), net	255	86
Total other income (expense), net	354	86
Income before income tax expense	98,997	79,032
Operating segments | Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	100,054	92,486
Operating expenses	76,923	72,657
Gross margin	23,131	19,829
Corporate general and administrative expenses	0	0
Operating income	23,131	19,829
Other income (expense):
Interest expense	(1)	0
Gain on sale of operations, net	0
Other income (expense), net	177	(24)
Total other income (expense), net	176	(24)
Income before income tax expense	23,307	19,805
Operating segments | National Practices
Segment Reporting Information [Line Items]
Revenue	11,466	10,490
Operating expenses	10,583	9,576
Gross margin	883	914
Corporate general and administrative expenses	0	0
Operating income	883	914
Other income (expense):
Interest expense	0	0
Gain on sale of operations, net	0
Other income (expense), net	0	0
Total other income (expense), net	0	0
Income before income tax expense	883	914
Corporate and Other
Segment Reporting Information [Line Items]
Revenue	0	0
Operating expenses	9,062	(1,734)
Gross margin	(9,062)	1,734
Corporate general and administrative expenses	15,598	16,309
Operating income	(24,660)	(14,575)
Other income (expense):
Interest expense	(3,640)	(1,259)
Gain on sale of operations, net	0
Other income (expense), net	4,680	(6,469)
Total other income (expense), net	1,040	(7,728)
Income before income tax expense	$ (23,620)	$ (22,303)