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. 25, 2019	Aug. 26, 2018
Numerator:
Net income attributable to Lamb Weston Holdings, Inc.	$ 115.7	$ 107.8
Less: Increase in redemption value of noncontrolling interests in excess of earnings allocated, net of tax benefits		0.9
Net income available to Lamb Weston common stockholders	$ 115.7	$ 106.9
Denominator:
Basic weighted average common shares outstanding	146.2	146.5
Add: Dilutive effect of employee incentive plans	0.8	0.7
Diluted weighted average common shares outstanding	147.0	147.2
Earnings per share
Basic (in dollars per share)	$ 0.79	$ 0.73
Diluted (in dollars per share)	$ 0.79	$ 0.73