Summary of Marketable Securities (Detail) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Cost	$ 51	$ 51
Unrealized Gains (Losses)	(1)	3
Fair Value	50	54
U.S. government and agencies
Cost	15	23
Fair Value	15	23
Corporate equity securities
Cost		5
Unrealized Gains (Losses)		3
Fair Value		8
Certificates of deposit
Cost	11	15
Fair Value	11	15
Mutual funds
Cost	25	8
Unrealized Gains (Losses)	(1)
Fair Value	$ 24	$ 8

Investments in debt and equity securities which are categorized neither as trading securities nor held-to-maturity securities and which are intended be sold or mature within one year from the balance sheet date or the normal operating cycle, whichever is longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income.

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+ Details