Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 52,760	$ 45,871
Asset-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	26,184	24,547
Separately Managed Accounts
Disaggregation of Revenue [Line Items]
Revenues	26,184	24,547
Asset-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	21,466	17,623
Impact of Fulcrum Fees
Disaggregation of Revenue [Line Items]
Revenues	(20)	(995)
Performance-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	493
Sub-Advised Accounts
Disaggregation of Revenue [Line Items]
Revenues	21,939	16,628
Asset-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	4,813	4,951
Expense Cap Reimbursements
Disaggregation of Revenue [Line Items]
Revenues	(224)	(255)
Performance-Based Fees
Disaggregation of Revenue [Line Items]
Revenues	48
Pzena Funds
Disaggregation of Revenue [Line Items]
Revenues	$ 4,637	$ 4,696