QUARTERLY FINANCIAL DATA (unaudited) - Tabular Disclosure (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended									12 Months Ended
	Aug. 30, 2020	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
QUARTERLY FINANCIAL DATA (unaudited)
Revenue		$ 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
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
Income before income taxes and equity method earnings		1.7	137.3	168.1	141.8	120.9	166.8	147.8	125.8	448.9	561.3	471.3
Income tax expense (benefit)		(2.8)	35.7	42.7	36.7	25.7	39.6	34.0	34.3	112.3	133.6	121.2
Net income (loss) 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
Earnings per share
Basic (in dollars per share)		$ (0.01)	$ 0.76	$ 0.96	$ 0.79	$ 0.76	$ 0.96	$ 0.74	$ 0.73	$ 2.50	$ 3.19	$ 2.83
Diluted (in dollars per share)		(0.01)	0.76	0.95	0.79	0.75	0.95	0.74	0.73	2.49	3.18	2.82
Dividends declared per common share (in dollars per share)	$ 0.23	$ 0.23000	$ 0.23000	$ 0.20000	$ 0.20000	$ 0.20000	$ 0.20000	$ 0.19125	$ 0.19125	$ 0.8600	$ 0.7825	$ 0.7575