Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 48,697	$ 50,877	$ 101,457	$ 96,748
Asset-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	23,756	26,525	49,940	51,072
Separately Managed Accounts
Disaggregation of Revenue [Line Items]
Revenues	23,756	26,525	49,940	51,072
Asset-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	19,819	20,350	41,285	37,973
Impact of Fulcrum Fees
Disaggregation of Revenue [Line Items]
Revenues	(0)	(958)	(20)	(1,953)
Performance-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	738	8	1,231	8
Sub-Advised Accounts
Disaggregation of Revenue [Line Items]
Revenues	20,557	19,400	42,496	36,028
Asset-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	4,606	5,157	9,419	10,109
Expense Cap Reimbursements
Disaggregation of Revenue [Line Items]
Revenues	(222)	(205)	(446)	(461)
Performance-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	0		48
Pzena Funds
Disaggregation of Revenue [Line Items]
Revenues	$ 4,384	$ 4,952	$ 9,021	$ 9,648