Investments - Available-for-sale and Held-to-maturity Investments (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Feb. 12, 2017	Feb. 18, 2018	Feb. 12, 2017	Sep. 03, 2017
Available-for-sale and Held-to-maturity [Line Items]
Available-for-sale, recorded basis		$ 937
Available-for-sale, cost basis, total		951
Held-to-maturity, cost basis		112
Total investments, recorded basis		1,049		$ 1,233
Proceeds from Sale of Available-for-sale Securities	$ 34	39	$ 66
Short-term Investments
Available-for-sale and Held-to-maturity [Line Items]
Unrealized gains/(loss), net		(14)		0
Total investments, recorded basis		1,049		1,233
Total investments, cost basis, total		1,063		1,233
Available-for-sale Securities [Member] | Short-term Investments
Available-for-sale and Held-to-maturity [Line Items]
Available-for-sale, recorded basis		937		948
Unrealized gains/(loss), net		(14)		0
Available-for-sale, cost basis, total		951		948
Available-for-sale Securities [Member] | Short-term Investments | Government and Agency Securities
Available-for-sale and Held-to-maturity [Line Items]
Available-for-sale, recorded basis		937		947
Unrealized gains/(loss), net		(14)		0
Available-for-sale, cost basis, total		951		947
Available-for-sale Securities [Member] | Short-term Investments | Mortgaged-backed Securities
Available-for-sale and Held-to-maturity [Line Items]
Available-for-sale, recorded basis				1
Unrealized gains/(loss), net				0
Available-for-sale, cost basis, total				1
Held-to-maturity Securities [Member] | Short-term Investments
Available-for-sale and Held-to-maturity [Line Items]
Held-to-maturity, recorded basis		112		285
Held-to-maturity, cost basis		112		285
Held-to-maturity Securities [Member] | Short-term Investments | Certificates of deposit
Available-for-sale and Held-to-maturity [Line Items]
Held-to-maturity, recorded basis		112		285
Held-to-maturity, cost basis		$ 112		$ 285