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Summary of Significant Accounting Policies (Tables) | 12 Months Ended
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Dec. 31, 2018
Accounting Policies [Abstract] |
Weighted-average useful lives of structures and machinery and and equipment | The following table details the weighted-average useful lives of structures and machinery and equipment by reporting segment (numbers in years):
| Structures |  | Machinery and equipment
Engineered Products and Solutions | 29 |  | 17
Global Rolled Products | 31 |  | 21
Transportation and Construction Solutions | 27 |  | 18
Weighted-average useful lives of software and other intangibles | The following table details the weighted-average useful lives of software and other intangible assets by reporting segment (numbers in years):
| Software |  | Other intangible assets
Engineered Products and Solutions | 5 |  | 33
Global Rolled Products | 5 |  | 9
Transportation and Construction Solutions | 5 |  | 16

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