Document And Entity Information	3 Months Ended
	Sep. 30, 2012	Oct. 29, 2012
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2012
Entity Registrant Name	AUTOMATIC DATA PROCESSING INC
Entity Central Index Key	0000008670
Current Fiscal Year End Date	--06-30
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		485,473,927