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		9 Months Ended
	Feb. 23, 2020	Feb. 24, 2019	Feb. 23, 2020	Feb. 24, 2019
Numerator:
Net income attributable to Lamb Weston Holdings, Inc.	$ 111.4	$ 141.4	$ 367.5	$ 368.2
Less: Increase in redemption value of noncontrolling interests in excess of earnings allocated, net of tax benefits		0.5		11.4
Net income available to Lamb Weston common stockholders	$ 111.4	$ 140.9	$ 367.5	$ 356.8
Denominator:
Basic weighted average common shares outstanding	146.2	146.6	146.2	146.5
Add: Dilutive effect of employee incentive plans	1.0	0.8	0.9	0.8
Diluted weighted average common shares outstanding	147.2	147.4	147.1	147.3
Earnings per share
Basic (in dollars per share)	$ 0.76	$ 0.96	$ 2.51	$ 2.44
Diluted (in dollars per share)	$ 0.76	$ 0.95	$ 2.50	$ 2.42