14. STOCK-BASED COMPENSATION (Details 3) - Stock Option and RSU Transactions - shares	3 Months Ended			9 Months Ended
	Feb. 28, 2021	Nov. 30, 2020	Aug. 31, 2020	Feb. 28, 2021
Available shares, beginning (in thousands)	1,212	1,319	1,650	1,650
Options granted (in thousands)	0	(73)	(200)
RSUs granted (in thousands)	(42)	(57)	(196)
Shares withheld for taxes and not issued (in thousands)	4	0	0	4
Options cancelled (in thousands)	21	185	188
RSUs cancelled (in thousands)	0	0	2
Options expired (in thousands)	0	(162)	(125)
Available shares, ending (in thousands)	1,195	1,212	1,319	1,195