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Debt (Letter of Credit) (Details) (USD $)
In Millions, unless otherwise specified |
Jun. 30, 2013
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Dec. 31, 2012
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|---|---|---|---|---|---|---|
| Line of Credit Facility [Line Items] | ||||||
| Letters of Credit Outstanding, Amount | $ 614 | $ 626 | ||||
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Corporate Revolving Facility [Member]
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| Line of Credit Facility [Line Items] | ||||||
| Letters of Credit Outstanding, Amount | 240 | [1] | 243 | [1] | ||
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CDH [Member]
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| Line of Credit Facility [Line Items] | ||||||
| Letters of Credit Outstanding, Amount | 243 | 253 | ||||
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Various Project Financing Facilities [Member]
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| Line of Credit Facility [Line Items] | ||||||
| Letters of Credit Outstanding, Amount | $ 131 | $ 130 | ||||
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