Assets and Liabilities Measured at Fair Value - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	$ 465	$ 570
Less amounts classified as current assets	(63)	(55)
Investments of insurance subsidiaries, noncurrent	402	515
Cross Currency Swap (Income Taxes and Other Liabilities) [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Liabilities, Fair Value	4	13
Interest Rate Swaps [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Liabilities, Fair Value	323	429
Equity Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	3	3
Debt Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	462	567
Debt Securities [Member] \| States and Municipalities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	393	418
Debt Securities [Member] \| Auction Rate Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	32	68
Debt Securities [Member] \| Asset-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	13	14
Debt Securities [Member] \| Money Market Funds [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	24	67
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	26	68
Less amounts classified as current assets	(24)	(55)
Investments of insurance subsidiaries, noncurrent	2	13
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member] \| Equity Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	2	1
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member] \| Debt Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	24	67
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member] \| Debt Securities [Member] \| Money Market Funds [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	24	67
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	406	432
Less amounts classified as current assets	(39)
Investments of insurance subsidiaries, noncurrent	367	432
Significant Other Observable Inputs (Level 2) [Member] \| Cross Currency Swap (Income Taxes and Other Liabilities) [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Liabilities, Fair Value	4	13
Significant Other Observable Inputs (Level 2) [Member] \| Interest Rate Swaps [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Liabilities, Fair Value	323	429
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	406	432
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| States and Municipalities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	393	418
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Asset-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	13	14
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	33	70
Investments of insurance subsidiaries, noncurrent	33	70
Significant Unobservable Inputs (Level 3) [Member] \| Equity Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	1	2
Significant Unobservable Inputs (Level 3) [Member] \| Debt Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	32	68
Significant Unobservable Inputs (Level 3) [Member] \| Debt Securities [Member] \| Auction Rate Securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Assets, Fair Value	$ 32	$ 68

- 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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