Basis of Presentation and Significant Accounting Policies - Additional Information (Details) $ in Thousands		12 Months Ended
	Nov. 01, 2021 reportingUnit	Dec. 31, 2021 USD ($) reportingUnit practiceGroup	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of practice groups | practiceGroup		3
Revenue		$ 1,104,925	$ 963,897	$ 948,424
Maximum maturity period of investments		3 months
Allowance for doubtful accounts		$ 16,158	14,894	14,379	$ 13,389
Goodwill		740,743	683,083	588,213
Assets		1,627,934	1,513,754
Total stockholders' equity		$ 704,548	702,620	659,238	$ 593,663
Intangible assets amortization period		7 years 4 months 24 days
Number of reporting units | reportingUnit	5	5
Net changes in the fair value of contingent consideration		$ 2,367	(629)	1,599
Unsecured credit facility		400,000
Other income (expense), net
Summary Of Significant Accounting Policies [Line Items]
Net changes in the fair value of contingent consideration		$ (2,400)	600	(1,600)
Performance Shares
Summary Of Significant Accounting Policies [Line Items]
Shares vesting term		3 years
Minimum
Summary Of Significant Accounting Policies [Line Items]
Shares vesting term		3 years
Intangible assets amortization period		3 years
Minimum | Capitalized software
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life		2 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Shares vesting term		4 years
Intangible assets amortization period		15 years
Maximum | Capitalized software
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life		7 years
Financial service
Summary Of Significant Accounting Policies [Line Items]
Revenue		$ 174,800	$ 159,400	$ 157,600