Investments - Maturities of Available-for-sale and Held-to-maturity Securities (Details) $ in Millions	Feb. 12, 2017 USD ($)
Available-for-sale, Cost Basis
Due in one year or less	$ 160
Due after one year through five years	837
Due after five years	55
Available-for-sale, cost basis, total	1,052
Available-for-sale, Fair Value
Due in one year or less	160
Due after one year through five years	836
Due after five years	54
Available-for-sale, recorded basis, total	1,050
Held-to-maturity
Due in one year or less	171
Due after one year through five years	0
Due after five years	0
Held-to-maturity, cost basis, total	$ 171