Segment Disclosures - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Revenue	$ 391,722	$ 300,730
Operating expenses (income)	290,299	223,971
Gross margin	101,423	76,759
Corporate general and administrative expenses	16,309	14,483
Operating income	85,114	62,276
Other income (expense):
Interest expense	(1,259)	(877)
Other (expense) income, net	(6,403)	4,789
Total other (expense) income, net	(7,662)	3,912
Income from continuing operations before income tax    expense	77,452	66,188
Financial Services
Segment Reporting Information [Line Items]
Revenue	288,746	204,149
Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	92,486	87,239
National Practices
Segment Reporting Information [Line Items]
Revenue	10,490	9,342
Operating segments | Financial Services
Segment Reporting Information [Line Items]
Revenue	288,746	204,149
Operating expenses (income)	209,800	141,746
Gross margin	78,946	62,403
Corporate general and administrative expenses	0	0
Operating income	78,946	62,403
Other income (expense):
Interest expense	0	0
Other (expense) income, net	86	98
Total other (expense) income, net	86	98
Income from continuing operations before income tax    expense	79,032	62,501
Operating segments | Benefits and Insurance Services
Segment Reporting Information [Line Items]
Revenue	92,486	87,239
Operating expenses (income)	72,657	66,933
Gross margin	19,829	20,306
Corporate general and administrative expenses	0	0
Operating income	19,829	20,306
Other income (expense):
Interest expense	0	0
Other (expense) income, net	(24)	174
Total other (expense) income, net	(24)	174
Income from continuing operations before income tax    expense	19,805	20,480
Operating segments | National Practices
Segment Reporting Information [Line Items]
Revenue	10,490	9,342
Operating expenses (income)	9,576	8,541
Gross margin	914	801
Corporate general and administrative expenses	0	0
Operating income	914	801
Other income (expense):
Interest expense	0	0
Other (expense) income, net	0	0
Total other (expense) income, net	0	0
Income from continuing operations before income tax    expense	914	801
Corporate and Other
Segment Reporting Information [Line Items]
Revenue	0	0
Operating expenses (income)	(1,734)	6,751
Gross margin	1,734	(6,751)
Corporate general and administrative expenses	16,309	14,483
Operating income	(14,575)	(21,234)
Other income (expense):
Interest expense	(1,259)	(877)
Other (expense) income, net	(6,465)	4,517
Total other (expense) income, net	(7,724)	3,640
Income from continuing operations before income tax    expense	$ (22,299)	$ (17,594)