Investments of Insurance Subsidiaries - Schedule of Investments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	$ 500	$ 552
Unrealized Amounts, Gains	13	24
Unrealized Amounts, Losses	(3)	(6)
Fair Value	510	570
Amounts classified as current assets	(62)	(55)
Investment carrying value	448	515
Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	498	550
Unrealized Amounts, Gains	11	23
Unrealized Amounts, Losses	(3)	(6)
Fair Value	506	567
Debt Securities [Member] \| States and Municipalities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	385	395
Unrealized Amounts, Gains	11	23
Unrealized Amounts, Losses	(3)
Fair Value	393	418
Debt Securities [Member] \| Auction Rate Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	7	74
Unrealized Amounts, Gains
Unrealized Amounts, Losses		(6)
Fair Value	7	68
Debt Securities [Member] \| Asset-Backed Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	12	14
Unrealized Amounts, Gains
Unrealized Amounts, Losses
Fair Value	12	14
Debt Securities [Member] \| Money Market Funds [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	94	67
Unrealized Amounts, Gains
Unrealized Amounts, Losses
Fair Value	94	67
Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	2	2
Unrealized Amounts, Gains	2	1
Unrealized Amounts, Losses
Fair Value	$ 4	$ 3

- Definition

Investments in debt and equity securities which are categorized neither as held-to-maturity nor trading and which are intended to be sold or mature more than one year from the balance sheet date or operating cycle, if 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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