PENSION AND POSTRETIREMENT BENEFITS (Tables)

9 Months Ended

Feb. 28, 2021

Compensation And Retirement Disclosure [Abstract]

Components of Pension Benefit and Other Postretirement Benefit Costs

Components of pension and other postretirement costs (benefits) are:

	Pension Plans
	Thirteen weeks ended						Thirty-nine weeks ended
	February 28, 2021			February 23, 2020			February 28, 2021			February 23, 2020
Service cost	$	2.7		$	2.8		$	9.0		$	8.4
Interest cost		21.7			27.8			65.1			89.8
Expected return on plan assets		(35.0	)		(42.0	)		(105.0	)		(124.7	)
Amortization of prior service cost		0.5			0.7			1.7			2.0
Curtailment loss		—			0.2			—			0.8
Settlement gain		—			(2.1	)		—			(2.1	)
Pension cost (benefit) — Company plans		(10.1	)		(12.6	)		(29.2	)		(25.8	)
Pension cost (benefit) — multi-employer plans		1.7			1.5			5.7			5.0
Total pension cost (benefit)	$	(8.4	)	$	(11.1	)	$	(23.5	)	$	(20.8	)

	Postretirement Plans
	Thirteen weeks ended						Thirty-nine weeks ended
	February 28, 2021			February 23, 2020			February 28, 2021			February 23, 2020
Service cost	$	—		$	—		$	0.1		$	0.1
Interest cost		0.4			0.6			1.1			1.9
Amortization of prior service cost (benefit)		(0.5	)		(0.5	)		(1.5	)		(1.5	)
Recognized net actuarial gain		(0.8	)		(1.1	)		(2.6	)		(3.4	)
Total postretirement cost (benefit)	$	(0.9	)	$	(1.0	)	$	(2.9	)	$	(2.9	)