Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities - current asset	$ 64	$ 56
Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset	126	116
Fair Value, Measurements, Recurring | Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities - current asset	64	56
Currency forward contracts - current asset	6	1
Fair Value, Measurements, Recurring | Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts - current liability	2	16
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities - current asset	36	33
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities - current asset	28	23
Currency forward contracts - current asset	6	1
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency forward contracts - current liability	2	16
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset	$ 126	$ 116