EMPLOYEE BENEFIT PLANS AND COLLECTIVE BARGAINING AGREEMENTS - Schedule of Components of Net Pension and Post-retirement Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Feb. 23, 2019	Feb. 24, 2018
Pension
Components of net expense:
Estimated return on plan assets	$ (112.6)	$ (119.6)
Service cost	52.4	49.8
Interest cost	85.8	88.3
Amortization of prior service cost	0.1	0.1
Amortization of net actuarial (gain) loss	(6.3)	0.4
Collington acquisition	0.0	0.0
Gain due to settlement accounting	0.0	(25.4)
Loss due to curtailment accounting	0.1	0.0
Net expense (benefit)	19.5	(6.4)
Changes in plan assets and benefit obligations recognized in Other comprehensive (loss) income:
Net actuarial loss (gain)	109.4	(138.6)
Gain due to settlement accounting	0.0	25.4
Loss due to curtailment accounting	(0.1)	0.0
Amortization of net actuarial gain (loss)	6.3	(0.4)
Prior service cost	3.1	0.0
Amortization of prior service cost	(0.1)	(0.1)
Total recognized in Other comprehensive (loss) income	118.6	(113.7)
Total net expense and changes in plan assets and benefit obligations recognized in Other comprehensive (loss) income	138.1	(120.1)
Other Post-Retirement Benefits
Components of net expense:
Estimated return on plan assets	0.0	0.0
Service cost	1.0	1.0
Interest cost	0.5	0.9
Amortization of prior service cost	3.7	3.7
Amortization of net actuarial (gain) loss	(0.2)	(0.1)
Collington acquisition	0.0	0.0
Gain due to settlement accounting	0.0	0.0
Loss due to curtailment accounting	0.0	0.0
Net expense (benefit)	5.0	5.5
Changes in plan assets and benefit obligations recognized in Other comprehensive (loss) income:
Net actuarial loss (gain)	(2.4)	(4.5)
Gain due to settlement accounting	0.0	0.0
Loss due to curtailment accounting	0.0	0.0
Amortization of net actuarial gain (loss)	0.2	0.1
Prior service cost	0.0	0.0
Amortization of prior service cost	(3.7)	(3.7)
Total recognized in Other comprehensive (loss) income	(5.9)	(8.1)
Total net expense and changes in plan assets and benefit obligations recognized in Other comprehensive (loss) income	$ (0.9)	$ (2.6)