Derivatives (Details-BS) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 17	$ 91
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	17	91
Derivative Liability, Fair Value, Gross Asset	0
Derivative Liability, Fair Value, Gross Liability	28
Derivative Liability, Fair Value, Net	28
Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	5	52
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	5	52
Commodity Contract [Member] | Other Current Assets [Member] | Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	5	52
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	5	52
Commodity Contract [Member] | Other Current Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0
Derivative Liability, Fair Value, Gross Liability	14
Derivative Liability, Fair Value, Net	14
Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0
Derivative Liability, Fair Value, Gross Liability	14
Derivative Liability, Fair Value, Net	14
Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	12	39
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	12	39
Derivative Liability, Fair Value, Gross Asset	0
Derivative Liability, Fair Value, Gross Liability	14
Derivative Liability, Fair Value, Net	14
Fair Value Hedging [Member] | Foreign Exchange Contract [Member] | Other Current Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	18
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	1	18
Fair Value Hedging [Member] | Foreign Exchange Contract [Member] | Other Current Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0
Derivative Liability, Fair Value, Gross Liability	14
Derivative Liability, Fair Value, Net	14
Fair Value Hedging [Member] | Interest rate [Member] | Other Noncurrent Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	11	21
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	$ 11	$ 21