Note 8 - Segment Information - Revenues from Countries That Are 10% Or More of Revenues (Details) - USD ($) $ in Thousands		12 Months Ended
		Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2017
Revenue by location		$ 1,435,351	$ 1,350,145	$ 1,221,179
UNITED STATES
Revenue by location	[1]	894,554	841,908	784,146
UNITED KINGDOM
Revenue by location	[1]	166,944	157,346	163,732
All Other European Countries [Member]
Revenue by location	[1]	241,140	230,243	166,600
Asia Pacific [Member]
Revenue by location	[1]	$ 132,713	$ 120,648	$ 106,701

[1] Revenues are attributed to countries based on the location of the client.