Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents	$ 235	$ 330
Marketable securities, fair value	138	131
Derivative Assets	3	3
Derivative Liability Fair Value Gross Liability	(3)	(2)
Corporate debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	88	82
U.S. government and agency debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	11	16
Non-U.S. government debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	1
Asset-backed debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	14	6
Certificates of deposit [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	17	16
Municipal debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	8	10
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents	209	284
Derivative Assets	0	0
Derivative Liability Fair Value Gross Liability	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Corporate debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | U.S. government and agency debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Non-U.S. government debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Asset-backed debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Certificates of deposit [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Municipal debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Significant Other Observable Inputs (Level 2) [Member]
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents	26	46
Derivative Assets	3	3
Derivative Liability Fair Value Gross Liability	(3)	(2)
Significant Other Observable Inputs (Level 2) [Member] | Corporate debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	88	82
Significant Other Observable Inputs (Level 2) [Member] | U.S. government and agency debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	11	16
Significant Other Observable Inputs (Level 2) [Member] | Non-U.S. government debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	1
Significant Other Observable Inputs (Level 2) [Member] | Asset-backed debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	14	6
Significant Other Observable Inputs (Level 2) [Member] | Certificates of deposit [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	17	16
Significant Other Observable Inputs (Level 2) [Member] | Municipal debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	8	10
Significant Unobservable Inputs (Level 3) [Member]
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents	0	0
Derivative Assets	0	0
Derivative Liability Fair Value Gross Liability	0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | U.S. government and agency debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Non-U.S. government debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Asset-backed debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Certificates of deposit [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Municipal debt securities [Member]
Assets and liabilities measured at fair value on a recurring basis
Marketable securities, fair value	$ 0	$ 0