Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 7	$ 9	$ 14	$ 16
Finite-lived intangible assets, future amortization expense, four year estimate, minimum			21
Finite-lived intangible assets, future amortization expense, four year estimate, maximum			$ 26
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives (in years)			1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives (in years)			20 years