Note 13 - Employee Stock Option and Retirement Plans (Details) - Summary of Share-Based Awards Available For Grant	1 Months Ended		12 Months Ended															0 Months Ended				1 Months Ended	12 Months Ended
	Apr. 30, 2013	Nov. 30, 2010	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2013 Restricted Stock [Member] Employee Option Plan [Member]		Aug. 31, 2012 Restricted Stock [Member] Employee Option Plan [Member]		Aug. 31, 2011 Restricted Stock [Member] Employee Option Plan [Member]		Aug. 31, 2013 Restricted Stock [Member] Non-Employee Stock Option Plan [Member]		Aug. 31, 2012 Restricted Stock [Member] Non-Employee Stock Option Plan [Member]		Aug. 31, 2011 Restricted Stock [Member] Non-Employee Stock Option Plan [Member]		Apr. 08, 2013 Restricted Stock [Member]	Apr. 14, 2011 Restricted Stock [Member]	Nov. 08, 2010 Restricted Stock [Member]	Feb. 09, 2010 Restricted Stock [Member]	Jan. 27, 2011 Restricted Stock [Member]	Aug. 31, 2013 Restricted Stock [Member]	Aug. 31, 2012 Restricted Stock [Member]	Aug. 31, 2013 Employee Option Plan [Member] Non-Performance Based [Member]	Aug. 31, 2012 Employee Option Plan [Member] Non-Performance Based [Member]	Aug. 31, 2011 Employee Option Plan [Member] Non-Performance Based [Member]	Aug. 31, 2013 Employee Option Plan [Member] Performance Based [Member]	Aug. 31, 2012 Employee Option Plan [Member] Performance Based [Member]	Aug. 31, 2011 Employee Option Plan [Member] Performance Based [Member]	Aug. 31, 2013 Employee Option Plan [Member]	Aug. 31, 2012 Employee Option Plan [Member]	Aug. 31, 2011 Employee Option Plan [Member]		Aug. 31, 2013 Non-Employee Stock Option Plan [Member] Non-Employee Director Grant [Member]	Aug. 31, 2012 Non-Employee Stock Option Plan [Member] Non-Employee Director Grant [Member]	Aug. 31, 2011 Non-Employee Stock Option Plan [Member] Non-Employee Director Grant [Member]	Aug. 31, 2011 Non-Employee Stock Option Plan [Member]		Aug. 31, 2013 Non-Employee Stock Option Plan [Member]	Aug. 31, 2012 Non-Employee Stock Option Plan [Member]
Note 13 - Employee Stock Option and Retirement Plans (Details) - Summary of Share-Based Awards Available For Grant [Line Items]
Balance																															4,340,000	4,977,000	2,216,000					162,000		107,000	126,000
Granted																									(645,000)	(540,000)	(91,000)	(1,011,000)	(907,000)	(892,000)					(19,000)	(21,000)	(15,000)
Granted	131,702		132,000	0	154,000	(329,000)	[1]		[1]	(386,000)	[1]		[1]		[1]		[1]	131,702	30,090	117,723	55,572	366	131,702	0
Share-based awards canceled/forfeited			(743,000)	(786,000)	(108,000)																										761,000	810,000	130,000
Amendment to the 2004 Stock Option and Award Plan to increase the number of shares available for issuance**		4,000,000																															4,000,000	[2]					[2]
Balance		1,000,000																													3,116,000	4,340,000	4,977,000					147,000		107,000	126,000

[1] Under the Company's option plan, for each restricted stock award granted/canceled/forfeited, an equivalent of 2.5 shares is added back to the available share-based awards balance.

[2] As of November 30, 2010, 1.0 million shares remained available for future grant of share-based awards under the Company's 2004 Stock Option and Award Plan, a number that the Company believed to be insufficient to meet its anticipated needs over the next 12 to 18 months. Therefore, the Company's Board of Directors approved an amendment to increase the maximum number of shares of FactSet common stock issuable under the 2004 Stock Option and Award Plan by 4,000,000 shares. The stockholders of FactSet approved the Amended and Restated FactSet Research Systems Inc. 2004 Stock Option and Award Plan at the Company's annual meeting held on December 14, 2010, including the reservation of an additional 4,000,000 shares of common stock for issuance.