Document and Entity Information	9 Months Ended
	Sep. 30, 2015 shares
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Trading Symbol	RHI
Entity Registrant Name	HALF ROBERT INTERNATIONAL INC /DE/
Entity Central Index Key	0000315213
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	132,686,250