Acquisitions - Additional Information (Details) - USD ($)				1 Months Ended	3 Months Ended		12 Months Ended
	Nov. 01, 2021	Mar. 01, 2021	Jul. 01, 2019	Dec. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Business Acquisition [Line Items]
Contingent consideration liability				$ 309,380,000	$ 305,553,000		$ 309,380,000
Decrease in contingent consideration liability					3,500,000	$ (2,500,000)
Goodwill				981,805,000	981,805,000		$ 981,805,000
USAA AMCO
Business Acquisition [Line Items]
Maximum aggregate contingent payment			$ 150,000,000.0		75,000,000.0
Maximum annual contingent payment			$ 37,500,000		$ 37,500,000
Period of time over which contingent payments will be made			4 years
Contingent consideration threshold percentage			80.00%
Annual revenue percentage requirement to achieve the maximum contingent payment			100.00%
Years remaining in earn out period					1 year 7 months 6 days		1 year 10 months 24 days
Contingent consideration liability				68,800,000	$ 66,000,000.0		$ 68,800,000
Decrease in contingent consideration liability					2,800,000
THB Acquisition
Business Acquisition [Line Items]
Purchase price		$ 547,000,000
THB Acquisition | Customer Relationship
Business Acquisition [Line Items]
Estimated acquisition costs allocated to definite- lived intangible asset		$ 600,000
NEC Acquisition
Business Acquisition [Line Items]
Contingent consideration liability					2,900,000
Purchase price	$ 63,100,000
Business acquisition, acquired percentage	100.00%
Payments to acquire business	$ 62,800,000
Net working capital adjustments	300,000						300,000
Additional payments in cash to acquire business based on revenue growth	$ 35,000,000.0
Cash based on revenue growth period	6 years
Contingent payment period one	36 months
Contingent payment period two	48 months
Contingent payment period three	60 months
Contingent payment compensation expense					$ 1,800,000
Assets acquired and liabilities assumed based upon their estimated fair values	$ 63,100,000
Goodwill expected to be deductible for tax purposes	41,000,000.0
Goodwill	$ 41,032,000
WestEnd Acquisition
Business Acquisition [Line Items]
Maximum aggregate contingent payment				320,000,000.0			320,000,000.0
Maximum annual contingent payment				$ 80,000,000.0
Period of time over which contingent payments will be made				4 years
Years remaining in earn out period				5 years 9 months 18 days	5 years 7 months 6 days
Contingent consideration liability				$ 239,700,000	$ 239,000,000.0		$ 239,700,000
Decrease in contingent consideration liability					700,000
Purchase price				$ 716,100,000
Business acquisition, acquired percentage				100.00%			100.00%
Payments to acquire business				$ 475,800,000
Net working capital adjustments				600,000	$ 600,000		$ 600,000
Cash payable for net working capital adjustments				$ 600,000			600,000
Period of time over which contingent "catch-up" provisions payments will be made				5 years 6 months
Maximum aggregate earn-out payments				$ 320,000,000.0			320,000,000.0
Maximum annual earn-out payments				80,000,000.0
Cash paid at closing placed in escrow				2,900,000			2,900,000
Amount available for purchase price adjustments				500,000			500,000
Amount available to compensate for eligible claims under purchase agreement indemnification provisions				2,400,000			2,400,000
Escrow funds reserved				500,000			500,000
Goodwill				536,023,000			536,023,000
WestEnd Acquisition | Third Amendment to 2019 Credit Agreement
Business Acquisition [Line Items]
Aggregate principal amount				$ 505,000,000.0			$ 505,000,000.0