PENSION AND POSTRETIREMENT BENEFITS (Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2016	Feb. 22, 2015	Feb. 28, 2016	Feb. 22, 2015
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 23.5	$ 22.1	$ 71.1	$ 66.4
Interest cost	40.0	40.4	122.0	121.1
Expected return on plan assets	(65.1)	(67.0)	(198.8)	(201.0)
Amortization of prior service cost	0.7	0.9	2.1	2.7
Special termination benefits	25.6	0.0	25.6	6.9
Benefit cost — Company plans	24.7	(3.6)	22.0	(3.9)
Pension benefit cost — multi-employer plans	32.4	2.8	38.8	9.5
Total benefit cost	57.1	(0.8)	60.8	5.6
Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.1	0.1	0.3	0.4
Interest cost	1.9	2.5	5.8	7.5
Amortization of prior service cost	(2.0)	(2.0)	(6.0)	(5.9)
Recognized net actuarial loss	0.0	0.9	0.0	2.6
Total benefit cost	$ 0.0	$ 1.5	$ 0.1	$ 4.6