Debt - Narrative (Details)	6 Months Ended
	Feb. 28, 2019 USD ($)	Feb. 28, 2018 USD ($)	Jan. 18, 2019 USD ($)	Dec. 21, 2018 USD ($)	Dec. 05, 2018 USD ($)	Nov. 30, 2018 USD ($)	Aug. 29, 2018 USD ($)	Aug. 24, 2017 USD ($)	Feb. 01, 2017 USD ($)
Line of Credit Facility [Line Items]
Interest paid	$ 349,000,000	$ 281,000,000
Revolving Credit Facility | January 2019 364-Day Revolving Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 2,000,000,000.0
Borrowing outstanding	0
Revolving Credit Facility | December 2018 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 1,000,000,000.0
Borrowing outstanding	500,000,000
Revolving Credit Facility | August 2018 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Borrowing outstanding	0
Face amount							$ 3,500,000,000.0
Term Loan | December 2018 Term Loan Credit Agreement
Line of Credit Facility [Line Items]
Face amount					$ 1,000,000,000.0
Long-term debt outstanding	$ 1,000,000,000
Letter of Credit | August 2018 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Face amount							$ 500,000,000
Term Loan | Maximum
Line of Credit Facility [Line Items]
Debt to total capitalization ratio	0.60
Line of Credit | November 2018 Credit Agreement
Line of Credit Facility [Line Items]
Borrowing outstanding	$ 700,000,000
Line of Credit | Revolving Credit Facility | November 2018 Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity						$ 500,000,000
Line of Credit | Unsecured Notes | November 2018 Credit Agreement
Line of Credit Facility [Line Items]
Face amount						$ 500,000,000
Medium-term Notes | August 2017 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity								$ 1,000,000,000.0
Medium-term Notes | 2017 Term Loan Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity								$ 1,000,000,000.0
Medium-term Notes | February 2017 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity									$ 1,000,000,000.0
Commercial paper
Line of Credit Facility [Line Items]
Average daily short-term borrowings	$ 2,400,000,000	$ 1,200,000,000
Weighted-average interest rate	2.96%	1.81%