SHARE-BASED PAYMENTS - Summary of Stock Appreciation Awards (Details) - Stock Appreciation Rights (SARs) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	May 31, 2020 USD ($) $ / shares shares
Number of Awards
Outstanding, beginning balance (in shares)	0.4
Exercised (in shares)	(0.2)
Forfeited (in shares)	(0.2)
Outstanding, ending balance (in shares)	0.0
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 28.13
Exercised (in dollars per share) | $ / shares	26.47
Forfeited (in dollars per share) | $ / shares	$ 30.76
Aggregate Intrinsic Value (in Millions)
Exercised | $	$ 0.6