XML 14 R1.htm IDEA: XBRL DOCUMENT v3.10.0.1
Document and Entity Information - shares
 9 Months Ended
Sep. 30, 2018
Oct. 25, 2018
Document Information [Line Items]    
Entity Registrant Name FEDERATED INVESTORS INC /PA/  
Entity Central Index Key 0001056288  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Document Period End Date Sep. 30, 2018  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Trading Symbol FII  
Entity Emerging Growth Company false  
Entity Small Business false  
Class A    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   9,000
Class B    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   100,491,180