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Summary of Significant Accounting Policies Discussion (Tables) | 12 Months Ended
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Dec. 31, 2017
Estimated Useful Life of Property, Plant, Equipment and Mine Development [Line Items] |
Estimated useful life of plant and equipment | The estimated useful lives by category of assets are as follows:
|  |  | Years
Building and improvements |  |  | 2 to 28
Machinery and equipment |  |  | 2 to 28
Leasehold improvements |  |  | Shorter of Useful Life or Remaining Life of Lease

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