Derivatives (Details-BS) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 76
Derivative Asset, Fair Value, Gross Liability	3
Derivative Asset, Fair Value, Net	73
Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	61
Derivative Asset, Fair Value, Gross Liability	3
Derivative Asset, Fair Value, Net	58
Commodity Contract [Member] | Other Noncurrent Assets [Member] | Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	6
Derivative Asset, Fair Value, Gross Liability	1
Derivative Asset, Fair Value, Net	5
Commodity Contract [Member] | Other Current Assets [Member] | Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	55
Derivative Asset, Fair Value, Gross Liability	2
Derivative Asset, Fair Value, Net	53
Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	15	$ 8
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	15	8
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	15	8
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	$ 15	$ 8