Investments (Schedule Of Amortized Cost Of Debt Securities Classified As Held-To-Maturity By Maturity Date) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Schedule of Investments [Line Items]
Foreign government debt, 1 Year or less	$ 88
Foreign government debt, After 1 Year through 5 Years	4
Foreign government debt, After 5 Years through 10 Years
Foreign government debt, After 10 Years	11
Foreign government debt, Total	$ 103