|
Debt (Letter of Credit) (Details) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2013
|
Dec. 31, 2012
|
|---|---|---|
| Line of Credit Facility [Line Items] | ||
| Letters of Credit Outstanding, Amount | $ 603 | $ 626 |
|
Corporate Revolving Facility [Member]
|
||
| Line of Credit Facility [Line Items] | ||
| Letters of Credit Outstanding, Amount | 222 | 243 |
|
CDH [Member]
|
||
| Line of Credit Facility [Line Items] | ||
| Letters of Credit Outstanding, Amount | 250 | 253 |
|
Various Project Financing Facilities [Member]
|
||
| Line of Credit Facility [Line Items] | ||
| Letters of Credit Outstanding, Amount | $ 131 | $ 130 |