Note 14 - Employee Stock Option and Retirment Plans - Summary of Restricted Stock Award (Details) - Restricted Stock [Member] - $ / shares	3 Months Ended					9 Months Ended
	May 31, 2017	Feb. 28, 2017		Nov. 30, 2016		May 31, 2017	May 31, 2016
Balance (in shares)	171,000	172,000		262,000		262,000
Balance (in dollars per share)	$ 136.65	$ 134.02		$ 126.27		$ 126.27
Granted (in shares)		8,000		5,000		12,927	93,375
Granted (in dollars per share)		$ 161.31		$ 151.63		$ 157.50	$ 159.42
Forfeited (in shares)	(3,000)	(3,000)
Forfeited (in dollars per share)	$ 116.38	$ 114.42
Vested (in shares)		(6,000)	[1]	(95,000)	[2]	(101,234)	(51,762)
Vested (in dollars per share)		$ 105.91	[1]	$ 112.70	[2]
Balance (in shares)	168,000	171,000		172,000		168,000
Balance (in dollars per share)	$ 136.95	$ 136.65		$ 134.02		$ 136.95

[1] Of the 6,357 restricted stock awards that vested during the second quarter of fiscal 2017, 5,150 related to awards granted on February 3, 2014. The remaining 40% of these restricted stock awards cliff vest after five years on February 3, 2019 and are amortized to expense over the vesting period using the straight-line attribution method. The other restricted stock awards that vested related to awards granted in February 2015 in connection with the Code Red acquisition, which vested 100% on February 9, 2017.

[2] Of the 94,877 restricted stock awards that vested during the first quarter of fiscal 2017, 73,522 related to awards granted on November 1, 2013. The remaining 40% of these restricted stock awards cliff vest after five years on November 1, 2018 and are amortized to expense over the vesting period using the straight-line attribution method. The other restricted stock awards that vested related primarily to awards granted in November 2015, which vest 20% per year on the anniversary date of the award.