Stockholders' Equity (Schedule of Adjustments to Accumulated Other Comprehensive Income (Loss), Net) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
As of December 31, 2012				$ (89)	[1]
Other comprehensive income, before reclassifications				41
Amounts reclassified from accumulated other comprehensive income				8
Income tax (provision) benefit	(3)	(1)	[1]	(7)		(6)	[1]
As of September 30, 2013	(47)			(47)
Other Comprehensive Income (Loss) on Marketable Securities, Net of Tax Portion Attributable To Equity Method Investee	1			1
Other Comprehensive Income (Loss), Net of Tax Portion Attributable To Equity Method Investee				(1)		(2)
Unrealized Gain (Loss) on Marketable Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
As of December 31, 2012				(1)
Other comprehensive income, before reclassifications				1
Amounts reclassified from accumulated other comprehensive income				0
Income tax (provision) benefit				0
As of September 30, 2013	0			0
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
As of December 31, 2012				(23)
Other comprehensive income, before reclassifications				41
Amounts reclassified from accumulated other comprehensive income				0
Income tax (provision) benefit				(4)
As of September 30, 2013	14			14
Gain (Loss) on Interest Rate Swaps [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
As of December 31, 2012				(50)
Other comprehensive income, before reclassifications				(1)
Amounts reclassified from accumulated other comprehensive income				8
Income tax (provision) benefit				(3)
As of September 30, 2013	(46)			(46)
Pension and Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
As of December 31, 2012				15	[1]
Other comprehensive income, before reclassifications				0
Amounts reclassified from accumulated other comprehensive income				0
Income tax (provision) benefit				0
As of September 30, 2013	$ 15			$ 15

[1] As Adjusted (Note 1)