|
Risk Management Fair Value of Derivative Contracts (Details) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2014
|
Dec. 31, 2013
|
|---|---|---|
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | $ 343 | $ 357 |
| Derivative Liability, Fair Value, Net | (274) | (311) |
|
Designated as Hedging Contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 327 | 335 |
| Derivative Liability, Fair Value, Net | (158) | (179) |
|
Not Designated as Hedging Instrument [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 16 | 22 |
| Derivative Liability, Fair Value, Net | (116) | (132) |
|
Commodity Contract [Member] | Designated as Hedging Contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 35 | 76 |
| Derivative Liability, Fair Value, Net | (64) | (63) |
|
Commodity Contract [Member] | Designated as Hedging Contracts [Member] | Current-Fair value of derivative contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 13 | 18 |
|
Commodity Contract [Member] | Designated as Hedging Contracts [Member] | Other Current Liabilities [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | (51) | (33) |
|
Commodity Contract [Member] | Designated as Hedging Contracts [Member] | Non-current-Fair value of derivative contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 22 | 58 |
|
Commodity Contract [Member] | Designated as Hedging Contracts [Member] | Non Current Liabilities [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | (13) | (30) |
|
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 6 | 4 |
| Derivative Liability, Fair Value, Net | (9) | (5) |
|
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current-Fair value of derivative contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 6 | 4 |
|
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | (9) | (5) |
|
Interest Rate Swap [Member] | Designated as Hedging Contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 292 | 259 |
| Derivative Liability, Fair Value, Net | (94) | (116) |
|
Power Derivative Contract [Member] | Not Designated as Hedging Instrument [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 10 | 18 |
| Derivative Liability, Fair Value, Net | (107) | (127) |
|
Power Derivative Contract [Member] | Not Designated as Hedging Instrument [Member] | Current-Fair value of derivative contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 2 | 7 |
|
Power Derivative Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | (49) | (54) |
|
Power Derivative Contract [Member] | Not Designated as Hedging Instrument [Member] | Non-current-Fair value of derivative contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 8 | 11 |
|
Power Derivative Contract [Member] | Not Designated as Hedging Instrument [Member] | Non Current Liabilities [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | (58) | (73) |
|
Fair Value Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Contracts [Member] | Current-Fair value of derivative contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 122 | 87 |
|
Fair Value Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Contracts [Member] | Other Current Liabilities [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | 0 | 0 |
|
Fair Value Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Contracts [Member] | Non-current-Fair value of derivative contracts [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 170 | 172 |
|
Fair Value Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Contracts [Member] | Non Current Liabilities [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | (94) | (116) |
|
Interest Rate Swap [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Asset, Fair Value, Net | 248 | 231 |
|
Interest Rate Swap [Member]
|
||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Net | $ (50) | $ (88) |