Cover Page - USD ($)	12 Months Ended
	Jun. 30, 2020	Jul. 31, 2020	Dec. 31, 2019
Cover [Abstract]
Document Type	10-K
Entity Public Float			$ 73,532,680,590
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	Yes
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Entity Registrant Name	AUTOMATIC DATA PROCESSING, INC.
Entity Central Index Key	0000008670
Current Fiscal Year End Date	--06-30
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		429,965,405
Document Annual Report	true
Document Transition Report	false
Entity File Number	1-5397
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-1467904
Entity Address, Address Line One	One ADP Boulevard
Entity Address, City or Town	Roseland,
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07068
City Area Code	973
Local Phone Number	974-5000
Title of 12(b) Security	Common Stock, $0.10 Par Value(voting)
Trading Symbol	ADP
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false