Derivative Instruments and Hedging Activities (Fair Value Of Derivatives Designated As Hedging Instruments) (Details) (Designated As Hedging Instrument [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Designated As Hedging Instrument [Member]
Derivative [Line Items]
Commodity Contracts Assets	$ 1	$ 1
Total fair value of derivatives assets designated as hedging instrument	1	1
Commodity Contracts Liabilities	0	0
Total fair value of derivatives liabilities designated as hedging instrument	$ 0	$ 0