Acquisitions - Additional Information (Details) - USD ($) $ in Thousands					3 Months Ended		9 Months Ended
	Sep. 30, 2021	Dec. 14, 2020	Oct. 02, 2020	Apr. 01, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Business Acquisition [Line Items]
Professional fees					$ 2,595	$ 2,627	$ 7,856	$ 5,177
Goodwill	$ 417,401				417,401		417,401		$ 369,982
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	0	0	1,100
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	1,200	0	1,600
Purchase consideration			189,138
Contingent consideration			572
Amount of term loan credit facility			89,500
Fair value of the remaining contingent consideration	$ 209				209		209
Payments to acquire business			94,216
Total Paid to Sellers							518
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							134
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					0	0	77	0
Purchase consideration		111,019
Amount of term loan credit facility		66,600
Payments to acquire business		82,596
Goodwill		73,274
Business acquisition, goodwill, expected tax deductible amount		18,700
Net identifiable assets acquired		$ 37,745
Bonaccord
Business Acquisition [Line Items]
Business acquisition effective date	Sep. 30, 2021
Expenses related to business acquisition	$ 1,900				1,900		1,900
Professional fees					1,900	$ 0	1,900	$ 0
Purchase consideration	55,896
Contingent consideration	16,970
Amount of term loan credit facility	35,000				35,000		35,000
Fair value of the remaining contingent consideration	17,000				17,000		17,000
Payments to acquire business	38,926
Total Paid to Sellers							0
Goodwill	42,930				42,930		42,930
Business acquisition, goodwill, expected tax deductible amount	42,900				42,900		42,900
Net identifiable assets acquired	$ 12,966				$ 12,966		$ 12,966
Percentage of net management fee earnings rights	5.00%				5.00%		5.00%
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
Equity interests acquired, percentage	0.10%				0.10%		0.10%
Bonaccord | Maximum
Business Acquisition [Line Items]
Contingent consideration	$ 20,000
Equity interests acquired, percentage	9.90%				9.90%		9.90%
Bonaccord | Other Income Expense
Business Acquisition [Line Items]
Contingent consideration							$ 0
Bonaccord | Compensation and benefits
Business Acquisition [Line Items]
Expenses related to business acquisition	$ 1,600				$ 1,600		1,600
Hark
Business Acquisition [Line Items]
Business acquisition effective date	Sep. 30, 2021
Purchase consideration	$ 7,200
Fair value of the remaining contingent consideration	2,200				2,200		2,200
Payments to acquire business	5,000
Goodwill	4,700				4,700		4,700
Net identifiable assets acquired	$ 2,500				$ 2,500		$ 2,500
Business Acquisitions
Business Acquisition [Line Items]
Business acquisition completed proforma date of acquisition							Jan. 01, 2020