Assets And Liabilities Measured At Fair Value (Schedule Related To The Auction Rate And Equity Securities Investments Of Insurance Subsidiaries At Fair Value) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Asset balances at December 31, 2011	$ 132
Unrealized gains included in other comprehensive income	3
Settlements	(63)
Asset balances at September 30, 2012	$ 72