Shareholders' Equity (Details)		3 Months Ended				6 Months Ended
	Jun. 11, 2021 shares	Jun. 30, 2021 vote $ / shares shares	Mar. 31, 2021 shares	Jun. 30, 2020 shares	Mar. 31, 2020 shares	Jun. 30, 2021 vote $ / shares shares	Jun. 30, 2020 $ / shares shares	Jul. 20, 2021 USD ($)	Dec. 31, 2020 $ / shares	Apr. 19, 2018 USD ($)	Feb. 11, 2014 USD ($)	Apr. 24, 2012 USD ($)
Class of Stock [Line Items]
Amount authorized under stock repurchase program | $										$ 30,000,000	$ 20,000,000	$ 10,000,000
Subsequent Event
Class of Stock [Line Items]
Amount authorized under stock repurchase program | $								$ 40,000,000
Class B unit exchange for Company Class A common stock
Class of Stock [Line Items]
Number of class B units exchanged for equivalent class A common shares (in shares) | shares	760,000
Common Class A
Class of Stock [Line Items]
Economic interest held in company by class of stock (in hundredths)		23.90%				23.90%			24.20%
Percentage of right to future income and distributions		22.20%				22.20%			22.40%
Par value (in dollars per share) | $ / shares		$ 0.01				$ 0.01			$ 0.01
Percentage of outstanding shares that represents rights of holders to receive distribution (in hundredths)		100.00%				100.00%
Common stock purchased and retired (in shares) | shares		97,656	275,218	266,238	823,792	372,874	1,090,030
Purchased under repurchase authorization at an average price per share (in dollars per share) | $ / shares						$ 9.21	$ 6.46
Common Class B
Class of Stock [Line Items]
Percentage of right to future income and distributions		68.70%				68.70%			70.10%
Par value (in dollars per share) | $ / shares		$ 0.000001				$ 0.000001			$ 0.000001
Voting rights (in votes) | vote						5
Percentage of stock holding that will entitle holders to one vote (in hundredths)						20.00%
Voting rights when class of stock constitutes less than 20% of all shares outstanding (in votes) | vote		1				1
Common stock purchased and retired (in shares) | shares		2,790	18,476		94,830	21,266	94,830
Purchased under repurchase authorization at an average price per share (in dollars per share) | $ / shares						$ 5.75	$ 5.97
Class B-1 Units
Class of Stock [Line Items]
Percentage of right to future income and distributions		9.10%				9.10%			7.50%
Voting rights (in votes) | vote						0
Number of shares issued | shares		0				0
Pzena Investment Management, LLC | Common Class B
Class of Stock [Line Items]
Economic interest held in company by class of stock (in hundredths)		73.40%				73.40%			75.80%
Pzena Investment Management, LLC | Class B-1 Units
Class of Stock [Line Items]
Economic interest held in company by class of stock (in hundredths)		2.70%				2.70%			0.00%