SEGMENTS - General Financial Information (Details) - USD ($) $ 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
Revenue information
Net sales	$ 832.5	$ 768.5	$ 790.7	$ 776.3	$ 777.0	$ 728.7	$ 740.3	$ 747.8	$ 3,168.0	$ 2,993.8	$ 2,925.0
Product contribution margin									763.9	641.8	567.9
Equity method investment earnings									53.3	71.7	42.7
Total product contribution margin plus equity method investment earnings									817.2	713.5	610.6
Other selling, general and administrative expenses									245.6	268.5	186.5
Interest expense, net									(61.2)	(5.9)	(6.1)
Income tax expense	41.2	44.0	33.9	51.0	20.3	53.2	38.7	32.3	170.2	144.5	140.4
Net income									340.2	294.6	277.6
Less: Income attributable to noncontrolling interests									13.3	9.3	9.3
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
Non-cash gain related to settlement of pension plan in earnings										17.7
Pretax professional fees expenses									26.5
Non-cash pre-tax gain on assets									3.1
Pre tax expense related to separation										5.3
Non-cash gain on the sale of land											5.1
Global
Revenue information
Net sales									1,624.8	1,549.4	1,512.9
Product contribution margin									343.0	296.5	253.7
Foodservice
Revenue information
Net sales									1,030.0	946.0	929.0
Product contribution margin									333.1	254.7	246.0
Retail
Revenue information
Net sales									384.9	372.1	355.6
Product contribution margin									78.3	69.6	47.6
Other
Revenue information
Net sales									128.3	126.3	127.5
Product contribution margin									$ 9.5	21.0	$ 20.6
Conagra
Revenue information
Charge for write-off of actuarial losses										$ 59.5
Minimum percentage of pension liability										10.00%