Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 8	$ 4	$ 24	$ 13
Finite-lived intangible assets, future amortization expense, four year estimate, minimum			22
Finite-lived intangible assets, future amortization expense, four year estimate, maximum			$ 31
Preliminary purchase price allocations finalization, period of time after acquisition (in years)			1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives (in years)			20 years
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives (in years)			1 year