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Basis of Presentation and Summary of Significant Accounting Policies Property, Plant and Equipment, Net (Details) (USD $) In Millions, unless otherwise specified | Mar. 31, 2014 | Dec. 31, 2013
--- | --- | ---
Property, Plant and Equipment [Line Items] |  |  |  |
Buildings, machinery and equipment | $ 16,516 | [1] | $ 15,838 | [1]
Geothermal properties | 1,267 |  | 1,265 |
Other | 167 |  | 164 |
Property, Plant and Equipment, Gross | 17,950 |  | 17,267 |
Less: Accumulated depreciation | 5,046 |  | 4,897 |
Property, Plant and Equipment, Gross, Less Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment | 12,904 |  | 12,370 |
Land | 109 |  | 103 |
Construction in progress | 585 |  | 522 |
Property, plant and equipment, net | $ 13,598 |  | $ 12,995 |
[1] | (1)The change from December 31, 2013 to March 31, 2014 can primarily be attributed to our acquisition of Guadalupe Energy Center on February 26, 2014.

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