Cash, Cash Equivalents and Investments (Unrealized Losses On Cash Equivalents and Investments) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Fair Value	$ 1,887	$ 2,071
Unrealized Losses	(6)	(6)
U.S. and foreign corporate debt securities
Schedule of Investments [Line Items]
Fair Value	1,718	1,964
Unrealized Losses	(5)	(5)
Mortgage-backed securities
Schedule of Investments [Line Items]
Fair Value	169	107
Unrealized Losses	$ (1)	$ (1)