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Summary of Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2017
Land Improvements [Member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 20 years
Assets under finance leases [member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 20 years
Bottom of range [member] | Buildings [member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 10 years
Bottom of range [member] | Machinery and equipment [member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 2 years
Bottom of range [member] | Office equipment [member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 3 years
Top of range [member] | Buildings [member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 20 years
Top of range [member] | Machinery and equipment [member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 5 years
Top of range [member] | Office equipment [member]  
Disclosure of significant accounting policies [line items]  
Useful lives of property, plant and equipment 5 years