Investments (Schedule Of Cost And Fair Value Of Equity Securities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Investments [Abstract]
Cost	$ 662	$ 671
Gross unrealized appreciation	29	18
Gross unrealized depreciation	(12)	(42)
Fair value	$ 679	$ 647

For an unclassified balance sheet, this item represents equity securities categorized neither as held-to-maturity nor trading.

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