Segment Disclosures - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Revenue	$ 410,539	$ 363,262	$ 1,263,647	$ 1,116,936
Operating expenses (income)	342,148	306,017	1,027,146	886,052
Gross margin	68,391	57,245	236,501	230,884
Corporate general and administrative expenses	13,136	15,893	44,527	43,128
Operating income	55,255	41,352	191,974	187,756
Other income (expense):
Interest expense	(5,848)	(2,305)	(15,023)	(5,209)
Gain on sale of operations, net	77	176	176	311
Other income (expense), net	(2,288)	(2,622)	8,245	(24,932)
Total other expense, net	(8,059)	(4,751)	(6,602)	(29,830)
Income before income tax expense	47,196	36,601	185,372	157,926
Financial Services
Segment Reporting Information [Line Items]
Revenue	298,372	259,998	932,388	808,052
Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	100,287	92,067	296,179	276,261
National Practices
Segment Reporting Information [Line Items]
Revenue	11,880	11,197	35,080	32,623
Operating segments | Financial Services
Segment Reporting Information [Line Items]
Revenue	298,372	259,998	932,388	808,052
Operating expenses (income)	249,680	220,337	737,568	639,780
Gross margin	48,692	39,661	194,820	168,272
Corporate general and administrative expenses	0	0	0	0
Operating income	48,692	39,661	194,820	168,272
Other income (expense):
Interest expense	0	0	0	0
Gain on sale of operations, net	77	176	176	311
Other income (expense), net	1,497	103	1,987	274
Total other expense, net	1,574	279	2,163	585
Income before income tax expense	50,266	39,940	196,983	168,857
Operating segments | Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	100,287	92,067	296,179	276,261
Operating expenses (income)	79,636	73,321	234,933	220,998
Gross margin	20,651	18,746	61,246	55,263
Corporate general and administrative expenses	0	0	0	0
Operating income	20,651	18,746	61,246	55,263
Other income (expense):
Interest expense	0	(4)	(1)	(5)
Gain on sale of operations, net	0	0	0	0
Other income (expense), net	267	2,402	597	2,366
Total other expense, net	267	2,398	596	2,361
Income before income tax expense	20,918	21,144	61,842	57,624
Operating segments | National Practices
Segment Reporting Information [Line Items]
Revenue	11,880	11,197	35,080	32,623
Operating expenses (income)	10,667	9,743	31,795	29,218
Gross margin	1,213	1,454	3,285	3,405
Corporate general and administrative expenses	0	0	0	0
Operating income	1,213	1,454	3,285	3,405
Other income (expense):
Interest expense	0	0	0	0
Gain on sale of operations, net	0	0	0	0
Other income (expense), net	0	8	1	9
Total other expense, net	0	8	1	9
Income before income tax expense	1,213	1,462	3,286	3,414
Corporate and Other
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Operating expenses (income)	2,165	2,616	22,850	(3,944)
Gross margin	(2,165)	(2,616)	(22,850)	3,944
Corporate general and administrative expenses	13,136	15,893	44,527	43,128
Operating income	(15,301)	(18,509)	(67,377)	(39,184)
Other income (expense):
Interest expense	(5,848)	(2,301)	(15,022)	(5,204)
Gain on sale of operations, net	0	0	0	0
Other income (expense), net	(4,052)	(5,135)	5,660	(27,581)
Total other expense, net	(9,900)	(7,436)	(9,362)	(32,785)
Income before income tax expense	$ (25,201)	$ (25,945)	$ (76,739)	$ (71,969)