Acquisitions - Additional Information (Details) $ in Millions		1 Months Ended	3 Months Ended	6 Months Ended
	Sep. 19, 2017 USD ($) distribution_center store	Mar. 28, 2018 USD ($) store	Feb. 28, 2018 USD ($) store	Feb. 28, 2018 USD ($) store	Aug. 31, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill			$ 17,017	$ 17,017	$ 15,632
Rite Aid Corporation
Business Acquisition [Line Items]
Number of stores expected to be acquired | store	1,932
Number of distribution centers expected to be acquired | distribution_center	3
Consideration to be transferred	$ 4,375
Number of locations acquired | store			1,445	1,542
Cash consideration				$ 3,336
Total consideration			$ 3,100	3,509
Goodwill			1,010	1,010
AllianceRx Walgreens Prime
Business Acquisition [Line Items]
Total consideration				720
Goodwill			$ 103	$ 103
Payer contracts | AllianceRx Walgreens Prime
Business Acquisition [Line Items]
Weighted-average useful life (in years)				15 years
Subsequent Event | Rite Aid Corporation
Business Acquisition [Line Items]
Number of locations acquired | store		390
Total consideration		$ 820