Investments (Schedule Of Cost And Fair Value Of Equity Securities) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Cost	$ 843	$ 707
Gross unrealized appreciation	45	41
Gross unrealized depreciation	(51)	(4)
Fair value	$ 837	$ 744

Amount of equity securities categorized neither as held-to-maturity nor as trading.

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+ Details