Fair Value Measurements (Unrealized Losses And Fair Value Of Investments With Unrealized Losses) (Details) - Jun. 30, 2015 $ in Millions	USD ($) investment
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | investment	93
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 188
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	94
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 189
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	73
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 111
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	73
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 111
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	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 27
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	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 28
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	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 14
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	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 14
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	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 19
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	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 19
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	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 17
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	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 17
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 0