Document And Entity Information - USD ($) $ in Billions	12 Months Ended
	Jun. 30, 2017	Aug. 25, 2017	Dec. 31, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	PAREXEL INTERNATIONAL CORP
Entity Central Index Key	0000799729
Current Fiscal Year End Date	--06-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		51,115,310
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 3.3