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Summary of Significant Accounting Policies Discussion (Tables)
 12 Months Ended
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