Fair Value Measurements (Schedule Of Major Categories Of Financial Assets And Liabilities Measured On A Nonrecurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Nonrecurring	$ 38	$ 107
Total Gains (Losses)	(44)	(130)
Long-Lived Assets Held And Used [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Nonrecurring	38	107
Total Gains (Losses)	(44)	(130)
Level 3 [Member] | Long-Lived Assets Held And Used [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Nonrecurring	$ 38	$ 107