Fair Value Measurements and Derivatives - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 105	$ 60
Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable	77	129
Fair Value, Measurements, Recurring | Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	105	60
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	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	61	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	0	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	44	23
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	77	129
Foreign Exchange Forward [Member] | Fair Value, Measurements, Recurring | Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency contracts asset value	2	4
Foreign Exchange Forward [Member] | Fair Value, Measurements, Recurring | Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency contracts liability value	3	1
Foreign Exchange Forward [Member] | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency contracts asset value	2	4
Foreign Exchange Forward [Member] | 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 contracts liability value	3	1
Currency Swap [Member] | Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency contracts asset value	1
Currency Swap [Member] | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency contracts asset value	$ 1