Available-For-Sale Securities (Amount Of Available-For-Sale Debt Securities By Maturity Periods) (Details) (USD $) In Millions	Sep. 30, 2011
Available-For-Sale Securities [Abstract]
Available-for-sale debt securities, less than 1 year	$ 11
Available-for-sale debt securities, 1-5 Years	141
Available-for-sale debt securities, 6-10 Years	172
Available-for-sale debt securities, 11-15 Years	43
Available-for-sale debt securities, 16-20 Years	18
Available-for-sale debt securities, over 20 Years	254
Available-for-sale debt securities, total	$ 639

For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

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+ Details