Note 16 - Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	May 31, 2017	May 31, 2016		May 31, 2017	May 31, 2016
Income before income taxes	$ 85,229	$ 88,857		$ 264,539	$ 261,177
Provision for income taxes	$ 19,815	$ 22,076		$ 65,832	$ 66,669
Effective tax rate	23.20%	24.80%	[1]	24.90%	25.50%	[1]

[1] In December 2015, the Consolidated Appropriations Act, 2016 (the “2016 ACT”) was signed into law. The ACT reinstated and made permanent the U.S. Federal R&D tax credit (the “R&D tax credit”), which had previously expired on December 31, 2014. The reenactment of the R&D tax credit was retroactive to January 1, 2015 and by providing for a permanent R&D tax credit, the 2016 ACT eliminates the yearly uncertainty surrounding the extension of the credit. Prior to the reenactment of the R&D tax credit, FactSet had not been permitted to factor it into its effective tax rate as it was not currently enacted tax law. The reenactment resulted in a discrete income tax benefit of $7.3 million during the second quarter of fiscal 2016 and reduced the Company’s effective tax rate for the nine months ended May 31, 2016 to 25.5%.