|
Fair Value Fair Value (Details 3) (USD $)
|
Sep. 30, 2012
|
Dec. 31, 2011
|
| Unobservable Inputs Valuation Techniques [Line Items] |
|
|
| Derivative Asset, Fair Value, Gross Asset |
$ 1,444,000,000 |
$ 2,805,000,000 |
| Derivative Liability, Fair Value, Gross Liability |
(1,435,000,000) |
(2,811,000,000) |
|
Commodity [Member]
|
|
|
| Unobservable Inputs Valuation Techniques [Line Items] |
|
|
| Derivative Asset, Fair Value, Gross Asset |
41,000,000 |
33,000,000 |
| Derivative Liability, Fair Value, Gross Liability |
(56,000,000) |
(104,000,000) |
|
Commodity Contract [Member]
|
|
|
| Unobservable Inputs Valuation Techniques [Line Items] |
|
|
| Derivative Asset, Fair Value, Gross Asset |
136,000,000 |
257,000,000 |
| Derivative Liability, Fair Value, Gross Liability |
(124,000,000) |
(140,000,000) |
|
Fair Value, Inputs, Level 3 [Member] | Commodity [Member]
|
|
|
| Unobservable Inputs Valuation Techniques [Line Items] |
|
|
| Derivative Asset, Fair Value, Gross Asset |
20,000,000 |
20,000,000 |
| Derivative Liability, Fair Value, Gross Liability |
(64,000,000) |
(14,000,000) |
| Minimum Weighted Average Range for Unobservable Inputs |
(0.63) |
|
| Maximum Weighted Average Range for Unobservable Inputs |
1.90 |
|
|
Fair Value, Inputs, Level 3 [Member] | Commodity Contract [Member]
|
|
|
| Unobservable Inputs Valuation Techniques [Line Items] |
|
|
| Derivative Asset, Fair Value, Gross Asset |
158,000,000 |
224,000,000 |
| Derivative Liability, Fair Value, Gross Liability |
(134,000,000) |
(192,000,000) |
| Minimum Weighted Average Range for Unobservable Inputs |
21 |
|
| Maximum Weighted Average Range for Unobservable Inputs |
32 |
|
|
Fair Value, Inputs, Level 3 [Member] | Commodity Contract 1 [Member]
|
|
|
| Unobservable Inputs Valuation Techniques [Line Items] |
|
|
| Minimum Weighted Average Range for Unobservable Inputs |
(1) |
|
| Maximum Weighted Average Range for Unobservable Inputs |
$ 15 |
|