Document And Entity Information - shares	3 Months Ended
	Nov. 30, 2015	Dec. 31, 2015
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)		41,190,780
Document Type	10-Q
Document Period End Date	Nov. 30, 2015
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q1
Amendment Flag	false