The following table summarizes the components of Property, net (dollars in millions): | | | | | | | | | | | | Estimated Useful Lives in Years | | December 31, 2013 | | December 31, 2012 | Land |
| | $ | 1,868 |
| | $ | 2,107 |
| Buildings and improvements | 5-40 | | 4,971 |
| | 4,601 |
| Machinery and equipment | 3-27 | | 15,222 |
| | 12,720 |
| Construction in progress |
| | 2,644 |
| | 3,018 |
| Real estate, plants and equipment | | | 24,705 |
| | 22,446 |
| Less: accumulated depreciation | | | (6,787 | ) | | (5,556 | ) | Real estate, plants and equipment, net | | | 17,918 |
| | 16,890 |
| Special tools, net | 1-15 | | 7,949 |
| | 7,306 |
| Total property, net | | | $ | 25,867 |
| | $ | 24,196 |
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