Investments - Maturities of Available-for-sale and Held-to-maturity Securities (Details) $ in Millions	Feb. 14, 2016 USD ($)
Available-for-sale, Cost Basis
Due in one year or less	$ 230
Due after one year through five years	644
Due after five years	58
Available-for-sale, cost basis, total	932
Available-for-sale, Fair Value
Due in one year or less	230
Due after one year through five years	650
Due after five years	60
Available-for-sale, recorded basis, total	940
Held-to-maturity
Due in one year or less	282
Due after one year through five years	0
Due after five years	0
Held-to-maturity, cost basis, total	$ 282