PENSION AND POSTRETIREMENT BENEFITS - Components of Pension Benefit and Other Postretirement Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	May 26, 2019	May 27, 2018	May 28, 2017
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 10.9	$ 42.8	$ 56.9
Interest cost	132.6	111.1	116.8
Expected return on plan assets	(174.4)	(218.3)	(207.4)
Amortization of prior service cost (benefit)	3.1	2.9	2.6
Special termination benefits	0.0	0.0	1.5
Recognized net actuarial loss (gain)	5.1	3.4	1.2
Settlement loss (gain)	0.0	1.3	13.8
Curtailment loss (gain)	0.0	0.7	1.7
Benefit cost — Company plans	(22.7)	(56.1)	(12.9)
Pension benefit cost — multi-employer plans	6.3	7.1	12.0
Total benefit (income) cost	(16.4)	(49.0)	(0.9)
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.1	0.2	0.3
Interest cost	3.8	3.9	4.6
Expected return on plan assets	0.0	0.0	0.0
Amortization of prior service cost (benefit)	(2.2)	(3.4)	(6.6)
Special termination benefits	0.0	0.0	0.0
Recognized net actuarial loss (gain)	(1.4)	0.0	0.5
Settlement loss (gain)	(1.0)	0.0	0.0
Curtailment loss (gain)	(0.6)	0.0	0.0
Benefit cost — Company plans	(1.3)	0.7	(1.2)
Pension benefit cost — multi-employer plans	0.0	0.0	0.0
Total benefit (income) cost	$ (1.3)	$ 0.7	$ (1.2)