Available-For-Sale Securities (Amount Of Available-For-Sale Debt Securities By Maturity Periods) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Less than one year	$ 58
Available-for-sale debt securities, 1-5 years	171
Available-for-sale debt securities, 6-10 years	191
Available-for-sale debt securities, 11-15 years	39
Available-for-sale debt securities, 16-20 years	9
Available-for-sale debt securities, Over 20 years	235
Total Available-for-Sale Debt Securities	703
Rabbi Trusts [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Less than one year	0
Available-for-sale debt securities, 1-5 years	59
Available-for-sale debt securities, 6-10 years	28
Available-for-sale debt securities, 11-15 years	8
Available-for-sale debt securities, 16-20 years	5
Available-for-sale debt securities, Over 20 years	54
Total Available-for-Sale Debt Securities	$ 154

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

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+ Details