Acquisitions - Additional Information (Details) - USD ($) $ in Thousands					9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 14, 2020	Oct. 02, 2020	Apr. 01, 2020	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Professional fees						$ 11,508	$ 13,953	$ 4,572
Goodwill						418,701	369,982	97,323
Five Points Capital
Business Acquisition [Line Items]
Business acquisition effective date				Apr. 01, 2020
Percentage of business acquisition				100.00%
Expenses related to business acquisition				$ 2,300
Professional fees						0	1,100	1,200
Purchase consideration				66,851
Payments to acquire business				46,751
Goodwill				48,630
Business acquisition, goodwill, expected tax deductible amount				0
Net identifiable assets acquired				$ 18,221
TrueBridge Capital
Business Acquisition [Line Items]
Business acquisition effective date			Oct. 02, 2020
Percentage of business acquisition			100.00%
Expenses related to business acquisition			$ 1,700
Professional fees						0	1,700	0
Purchase consideration			189,138
Contingent consideration			572
Amount of term loan credit facility			89,500
Payments to acquire business			94,216
Total Paid to Sellers						700
Goodwill			150,567
Business acquisition, goodwill, expected tax deductible amount			73,700
Net identifiable assets acquired			$ 38,571
TrueBridge Capital | Other Income Expense
Business Acquisition [Line Items]
Contingent consideration						100
Enhanced
Business Acquisition [Line Items]
Business acquisition effective date		Dec. 14, 2020
Percentage of business acquisition		100.00%
Expenses related to business acquisition		$ 3,700
Professional fees						$ 100	3,600	0
Purchase consideration		111,019
Amount of term loan credit facility		66,600
Payments to acquire business		82,596
Goodwill		72,507
Business acquisition, goodwill, expected tax deductible amount		18,700
Net identifiable assets acquired		$ 38,512
Bonaccord
Business Acquisition [Line Items]
Business acquisition effective date	Sep. 30, 2021
Percentage of business acquisition						1.70%
Expenses related to business acquisition	$ 500				$ 500
Revenues						$ 2,600
Revenues						150,500
Purchase consideration	56,362
Contingent consideration	17,435
Amount of term loan credit facility	35,000				35,000
Contingent consideration obligation						19,100
Payments to acquire business	38,927
Total Paid to Sellers						$ 0
Goodwill	42,936				42,936
Business acquisition, goodwill, expected tax deductible amount	42,900				42,900
Net identifiable assets acquired	$ 13,426				$ 13,426
Bonaccord | Restricted Stock Units (RSUs) [Member]
Business Acquisition [Line Items]
Number of restricted stock units allocated and granted to employee	1,113,637				1,113,637	0
Bonaccord | Third Party
Business Acquisition [Line Items]
Percentage of net management fee earnings rights	15.00%				15.00%	15.00%
Bonaccord | Minimum
Business Acquisition [Line Items]
Contingent consideration	$ 0
Bonaccord | Maximum
Business Acquisition [Line Items]
Contingent consideration	$ 20,000
Bonaccord | Professional Fees
Business Acquisition [Line Items]
Expenses related to business acquisition						$ 500	$ 0	$ 0
Bonaccord | Other Income Expense
Business Acquisition [Line Items]
Contingent consideration						$ 2,100
Hark
Business Acquisition [Line Items]
Business acquisition effective date	Sep. 30, 2021
Purchase consideration	$ 7,200
Contingent consideration obligation	2,200				$ 2,200
Payments to acquire business	5,000
Goodwill	4,700				4,700
Net identifiable assets acquired	$ 2,500				$ 2,500
Hark | Restricted Stock Units (RSUs) [Member]
Business Acquisition [Line Items]
Number of restricted stock units allocated and granted to employee	95,455				95,455	0
Business Acquisitions
Business Acquisition [Line Items]
Business acquisition completed proforma date of acquisition					Jan. 01, 2019