Business Combinations - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($) business	Sep. 30, 2020 USD ($)
Business Acquisition, Contingent Consideration [Line Items]
Annual revenue	$ 71,900	$ 24,600
Annual income before tax	6,100	5,900
Proceeds from sales of divested operations	$ 9,785	651
Benefits and Insurance Services Practice Group
Business Acquisition, Contingent Consideration [Line Items]
Number of businesses sold | business	1
Proceeds from sales of divested operations	$ 9,700
Gain from the sale of its individual wealth management business	$ 6,400	$ 100
Client List
Business Acquisition, Contingent Consideration [Line Items]
Acquired finite-lived intangible assets, useful life	10 years
Other Intangibles
Business Acquisition, Contingent Consideration [Line Items]
Acquired finite-lived intangible assets, useful life	3 years