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								12 Months Ended
	May 28, 2017	Feb. 26, 2017	Nov. 27, 2016	Aug. 28, 2016	May 29, 2016	Feb. 28, 2016	Nov. 29, 2015	Aug. 30, 2015	May 28, 2017	May 29, 2016	May 31, 2015
Numerator:
Net income attributable to Lamb Weston Holdings, Inc.	$ 75.9	$ 84.2	$ 87.2	$ 79.6	$ 42.6	$ 107.4	$ 73.3	$ 62.0	$ 326.9	$ 285.3	$ 268.3
Less: Increase in redemption value of noncontrolling interests in excess of earnings allocated									(2.1)	(4.8)	(1.7)
Net income available to Lamb Weston common stockholders									$ 324.8	$ 280.5	$ 266.6
Denominator:
Basic weighted average common shares outstanding									146.1	146.0	146.0
Add: Dilutive effect of employee incentive plans									0.5
Diluted weighted average common shares outstanding									146.6	146.0	146.0
Earnings per share
Basic (in dollars per share)	$ 0.52	$ 0.57	$ 0.59	$ 0.54	$ 0.29	$ 0.71	$ 0.50	$ 0.42	$ 2.22	$ 1.92	$ 1.83
Diluted (in dollars per share)	$ 0.51	$ 0.57	$ 0.59	$ 0.54	$ 0.29	$ 0.71	$ 0.50	$ 0.42	$ 2.22	$ 1.92	$ 1.83