BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Millions					4 Months Ended
	Jun. 25, 2020 shares	Jun. 09, 2020 USD ($) shares	May 14, 2020 USD ($) shares	Apr. 25, 2019	Jun. 20, 2020 USD ($) division store_format segment shares	Jun. 15, 2019 USD ($)	Feb. 29, 2020 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash					$ 42.3		$ 8.2
LIFO expense (benefit)					13.1	$ 10.5
Equity-based compensation expense					1.2	1.2
Compensation cost not yet recognized					$ 8.8
Period for recognition of unrecognized compensation cost					3 years 1 month 20 days
Repurchase of common stock		$ 1,680.0			$ 1,680.0	0.0
Income tax expense					$ 201.9	$ 15.7
Effective tax rate					25.60%	24.30%
Number of divisions | division					13
Number of reportable segments | segment					1
Number of store format | store_format					1
Receivables, net					$ 530.0		525.3
Contract liability related to gift cards					62.2		52.2
Pharmacy
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, net					246.1		$ 218.5
Common Stock
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of shares repurchased (in shares) | shares		101,611,736
Phantom units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity-based compensation expense					17.8	$ 9.9
Income tax benefit					$ 4.6	$ 2.6
Grants in period (in shares) | shares			1,000,000.0
Awards converted (in shares) | shares			4,300,000		11,300,000
Compensation cost not yet recognized					$ 87.9
Number of unvested phantom units (in shares) | shares					9,400,000
Period for recognition of unrecognized compensation cost					2 years 10 days
Phantom units | Investor Incentive Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Units received upon vesting (in shares) | shares					1
Restricted Stock Units (RSU) Deemed Not Granted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Awards converted (in shares) | shares					1,900,000
RSU Time Based Vesting
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Grants in period (in shares) | shares			3,200,000
RSU Performance Based Member
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Grants in period (in shares) | shares			400,000
RSU Deemed Granted Upon Establishment Of Annual Performance Target
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Grants in period (in shares) | shares			700,000
Restricted Stock Units (RSUs)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Grants in period (in shares) | shares			3,600,000
Grant fate fair value			$ 57.8
President and Chief Executive Officer | Direct Equity Interest
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Award vesting period				5 years
Award Based On Service Period | President and Chief Executive Officer | Direct Equity Interest
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting percentage				50.00%
Award Based On Service Period And Achievement Of Certain Performance Based Thresholds | President and Chief Executive Officer | Direct Equity Interest
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting percentage				50.00%
Subsequent Event | IPO | RSUs
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Exchanged | shares	1,700,000
Subsequent Event | IPO | Restricted Stock Units (RSU), Performance Based, Deemed Not Granted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Exchanged | shares	600,000