Earnings Per Share Attributable to Federated Investors, Inc. Shareholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator
Net Income Attributable to Federated Investors, Inc.	$ 72,962	$ 59,608	$ 190,232	$ 158,761
Less: Total Net Income Available to Participating Unvested Restricted Shareholders	(2,774)	(2,355)	(7,322)	(6,261)
Total Net Income Attributable to Federated Common Stock - Basic	70,188	57,253	182,910	152,500
Less: Total Net Income Available to Unvested Restricted Shareholders of a Nonpublic Consolidated Subsidiary	(258)	(480)	(457)	(480)
Total Net Income Attributable to Federated Common Stock - Diluted	$ 69,930	$ 56,773	$ 182,453	$ 152,020
Denominator
Basic Weighted-Average Federated Common Stock (in shares)	97,306	96,664	97,211	97,013
Dilutive Potential Shares from Stock Options (in shares)	0	0	0	1
Diluted Weighted-Average Federated Common Stock (in shares)	97,306	96,664	97,211	97,014
Earnings Per Share
Net Income Attributable to Federated Common Stock – Basic and Diluted (usd per share)	$ 0.72	$ 0.59	$ 1.88	$ 1.57