PENSION AND POSTRETIREMENT BENEFITS - Components of Pension Benefit and Other Postretirement Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Feb. 25, 2018	Nov. 26, 2017	Feb. 26, 2017	Feb. 25, 2018	Feb. 26, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit cost (benefit) — Company plans	$ (0.2)		$ 3.9	$ 5.5	$ 9.0
Total cost (benefit)	(17.4)		8.6	(33.2)	1.3
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	9.3		12.2	35.2	44.8
Interest cost	27.6		28.9	83.5	88.8
Expected return on plan assets	(54.8)		(50.9)	(163.6)	(158.6)
Amortization of prior service cost	0.7		0.7	2.1	2.0
Recognized net actuarial loss	0.0	$ 3.4	0.0	3.4	0.0
Settlement charge	0.0		13.8	0.0	13.8
Special termination benefits	0.0		0.0	0.0	1.5
Curtailment loss	0.0	$ 0.7	0.0	0.7	0.0
Benefit cost (benefit) — Company plans	(17.2)		4.7	(38.7)	(7.7)
Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.0		0.0	0.0	0.1
Interest cost	1.0		1.1	2.8	3.2
Amortization of prior service cost	(0.9)		(1.6)	(2.5)	(4.9)
Recognized net actuarial loss	0.0		0.1	0.0	0.3
Total cost (benefit)	$ 0.1		$ (0.4)	$ 0.3	$ (1.3)