v3.7.0.1
Document and Entity Information - shares
6 Months Ended
Jul. 02, 2017
Jul. 31, 2017
Document Information [Line Items]    
Entity Registrant Name KELLY SERVICES INC  
Document Type 10-Q  
Current Fiscal Year End Date --12-31  
Amendment Flag false  
Entity Central Index Key 0000055135  
Entity Current Reporting Status Yes  
Entity Filer Category Accelerated Filer  
Document Period End Date Jul. 02, 2017  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q2  
Class A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   34,871,144
Class B Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   3,437,643