Fair Value Measurements (Unrealized Losses And Fair Value Of Investments With Unrealized Losses) (Details) $ in Millions | Sep. 30, 2015USD ($)investment |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | investment | 32 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 37 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $ 0 |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | investment | 33 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | $ 38 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ 0 |
Asset-backed Securities | |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | investment | 25 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 21 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $ 0 |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | investment | 26 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | $ 22 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ 0 |
Foreign Government Debt Securities | |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | investment | 4 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 10 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $ 0 |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | investment | 4 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | $ 10 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ 0 |
US Government Agencies Debt Securities | |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | investment | 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 5 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $ 0 |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | investment | 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | $ 5 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ 0 |
United States Debt | |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | investment | 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $ 0 |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | investment | 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | $ 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ 0 |
Certificate of deposit | |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | investment | 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $ 0 |
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | investment | 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | $ 1 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ 0 |