Fair Value Measurements and Derivatives - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities - current asset	$ 63	$ 60
Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset	72	129
Fair Value, Measurements, Recurring | Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset	61
Marketable securities - current asset	63	60
Currency forward contracts - current asset	9	4
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	1
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset	0
Marketable securities - current asset	38	37
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset		0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset	0
Marketable securities - current asset	25	23
Currency forward contracts - current asset	9	4
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	1
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	72	129
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable - noncurrent asset	61
Marketable securities - current asset