Non-Controlling Interests (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Noncontrolling Interest [Line Items]
Net Income Attributable to Non-Controlling Interests	$ 12,840	$ 14,143
Non-Controlling Interests of Pzena Investment Management, LLC
Noncontrolling Interest [Line Items]
Net Income Attributable to Non-Controlling Interests	12,712	14,113
Non-Controlling Interests of Consolidated Subsidiaries
Noncontrolling Interest [Line Items]
Net Income Attributable to Non-Controlling Interests	$ 128	$ 30