SEGMENTS - Tabular Disclosure (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2020	Feb. 23, 2020	Nov. 24, 2019	Aug. 25, 2019	May 26, 2019	Feb. 24, 2019	Nov. 25, 2018	Aug. 26, 2018	May 31, 2020	May 26, 2019	May 27, 2018
Segment information
Net sales	$ 846.9	$ 937.3	$ 1,019.2	$ 989.0	$ 1,003.4	$ 926.8	$ 911.4	$ 914.9	$ 3,792.4	$ 3,756.5	$ 3,423.7
Product contribution margin									872.2	971.1	847.9
Advertising and promotion expenses									23.0	32.4	31.6
Gross profit	111.1	250.4	285.1	248.6	250.5	273.4	249.0	230.6	895.2	1,003.5	879.5
Selling, general and administrative expenses									338.3	335.1	299.4
Income from operations									556.9	668.4	580.1
Interest expense, net									108.0	107.1	108.8
Income tax expense	(2.8)	35.7	42.7	36.7	25.7	39.6	34.0	34.3	112.3	133.6	121.2
Equity method investment earnings									29.3	59.5	83.6
Net income									365.9	487.2	433.7
Less: Income attributable to noncontrolling interests										8.6	16.9
Net income attributable to Lamb Weston Holdings, Inc.	$ (1.6)	$ 111.4	$ 140.4	$ 115.7	$ 110.4	$ 141.4	$ 119.0	$ 107.8	365.9	478.6	416.8
Global
Segment information
Net sales									1,973.6	1,961.5	1,744.2
Product contribution margin									374.5	446.3	375.7
Foodservice
Segment information
Net sales									1,069.1	1,156.1	1,099.1
Product contribution margin									356.0	402.4	365.9
Retail
Segment information
Net sales									595.5	498.3	449.2
Product contribution margin									117.6	98.8	87.3
Other
Segment information
Net sales									154.2	140.6	131.2
Product contribution margin									$ 24.1	$ 23.6	$ 19.0