COVER - USD ($)	12 Months Ended
COVER - USD ($)	Aug. 31, 2026	Oct. 15, 2026	Feb. 27, 2026
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Aug. 31, 2026
Current Fiscal Year End Date	--08-31
Document Transition Report	false
Entity File Number	1-11869
Entity Registrant Name	FACTSET RESEARCH SYSTEMS INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3362547
Entity Address, Address Line One	45 Glover Avenue
Entity Address, City or Town	Norwalk
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06850
City Area Code	203
Local Phone Number	810-1000
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	FDS
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 7,928,656,331
Entity Common Stock, Shares Outstanding		35,255,660
Documents Incorporated by Reference	Certain information required by Part III of this Annual Report on Form 10-K is incorporated by reference to our definitive Proxy Statement for our 2026 Annual Meeting of Stockholders, which will be filed with the Securities and Exchange Commission not later than 120 days after August 31, 2026.
Entity Central Index Key	0001013237
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	FY
Amendment Flag	false
New York Stock Exchange LLC
Entity Information [Line Items]
Security Exchange Name	NYSE
The Nasdaq Stock Market
Entity Information [Line Items]
Security Exchange Name	NASDAQ