Debt (Letter of Credit) (Details) - USD ($) $ in Millions |
Jun. 30, 2015 |
Dec. 31, 2014 |
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|---|---|---|---|---|
| Line of Credit Facility [Line Items] | ||||
| Letters of Credit Outstanding, Amount | $ 642 | $ 644 | ||
| Corporate Revolving Facility [Member] | ||||
| Line of Credit Facility [Line Items] | ||||
| Letters of Credit Outstanding, Amount | [1] | 179 | 223 | |
| CDH [Member] | ||||
| Line of Credit Facility [Line Items] | ||||
| Letters of Credit Outstanding, Amount | 244 | 214 | ||
| Various Project Financing Facilities [Member] | ||||
| Line of Credit Facility [Line Items] | ||||
| Letters of Credit Outstanding, Amount | $ 219 | $ 207 | ||
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