Note 13 - Employee Stock Option and Retirement Plans - Summary of Stock Option Activity (Details) - $ / shares	3 Months Ended
	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	May 31, 2018	[1]
Balance (in shares)	3,216	3,457	3,143
Balance, weighted average price per share (in dollars per share)	$ 164,420	$ 162,680	$ 153,050
Granted (in shares)	2		455
Granted, weighted average price per share (in dollars per share)	$ 267,020		$ 221,930
Exercised (in shares)	(279)	(207)	(117)
Exercised, weighted average price per share (in dollars per share)	$ 137,820	$ 136,300	$ 132,810
Forfeited (in shares)	(73)	(61)	(24)
Forfeited, weighted average price per share (in dollars per share)	$ 168,420	$ 152,190	$ 169,470
Employee Option Plan [Member]
Granted (in shares)		6
Granted, weighted average price per share (in dollars per share)		$ 207,840
Non-Employee Director Grant [Member]
Granted (in shares)		21
Granted, weighted average price per share (in dollars per share)		$ 207,880

[1] There were no employee stock options granted during the three months ended May 31, 2018.