EARNINGS PER SHARE - Computation of Basic and Diluted Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Aug. 26, 2018	Aug. 27, 2017
Numerator:
Net income attributable to Lamb Weston Holdings, Inc.	$ 107.8	$ 83.4
Less: Increase in redemption value of noncontrolling interests in excess of earnings allocated	0.9	0.8
Net income available to Lamb Weston common stockholders	$ 106.9	$ 82.6
Denominator:
Basic weighted average common shares outstanding	146.5	146.2
Add: Dilutive effect of employee incentive plans	0.7	0.6
Diluted weighted average common shares outstanding	147.2	146.8
Earnings per share
Basic (in dollars per share)	$ 0.73	$ 0.56
Diluted (in dollars per share)	$ 0.73	$ 0.56