Document And Entity Information - shares	9 Months Ended
	May 31, 2017	Jun. 30, 2017
Document Information [Line Items]
Entity Registrant Name	FACTSET RESEARCH SYSTEMS INC
Entity Central Index Key	0001013237
Trading Symbol	fds
Current Fiscal Year End Date	--08-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding (in shares)		39,228,289
Document Type	10-Q
Document Period End Date	May 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Amendment Flag	false