PENSION AND POSTRETIREMENT BENEFITS - Components of Pension Benefit and Other Postretirement Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 26, 2017	Feb. 28, 2016	Feb. 26, 2017	Feb. 28, 2016
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 12.2	$ 23.5	$ 44.8	$ 71.1
Interest cost	28.9	40.0	88.8	122.0
Expected return on plan assets	(50.9)	(65.1)	(158.6)	(198.8)
Amortization of prior service cost	0.7	0.7	2.0	2.1
Settlement charge	13.8	0.0	13.8	0.0
Special termination benefits	0.0	25.6	1.5	25.6
Benefit cost — Company plans	4.7	24.7	(7.7)	22.0
Pension benefit cost — multi-employer plans	3.9	32.4	9.0	38.8
Total cost (benefit)	8.6	57.1	1.3	60.8
Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.0	0.1	0.1	0.3
Interest cost	1.1	1.9	3.2	5.8
Amortization of prior service cost	(1.6)	(2.0)	(4.9)	(6.0)
Recognized net actuarial loss	0.1	0.0	0.3	0.0
Total cost (benefit)	$ (0.4)	$ 0.0	$ (1.3)	$ 0.1