Earnings per Share - Diluted Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Diluted Net Income [Abstract]
Less: Net Income Attributable to Non-Controlling Interests	$ 15,185	$ 14,228	$ 43,213	$ 37,110
Net Income of Pzena Investment Management, Inc.	4,262	2,989	11,257	7,954
Diluted Net Income	15,786	11,862	44,033	31,077
Pzena Investment Management, LLC
Diluted Net Income [Abstract]
Net Income Attributable to Non-Controlling Interests	15,169	14,013	43,200	36,518
Less: Assumed Corporate Income Taxes	3,645	5,140	10,424	13,395
Less: Net Income Attributable to Non-Controlling Interests	11,524	8,873	32,776	23,123
Net Income of Pzena Investment Management, Inc.	4,262	2,989	11,257	7,954
Diluted Net Income	$ 15,786	$ 11,862	$ 44,033	$ 31,077