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Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives and Depreciation Calculation Methods (Detail)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Engineering equipment [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Depreciation method Straight-line  
Office equipment [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Depreciation method Straight-line  
Other [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Depreciation method Straight-line  
Leasehold improvements [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Depreciation method Straight-line over term of lease to a maximum of15 years or the improvement's economic life  
Estimated Lives 15 years  
Bottom of range [member] | Engineering equipment [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated Lives 5 years 20 percent
Bottom of range [member] | Office equipment [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated Lives 5 years 20 percent
Bottom of range [member] | Other [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated Lives 5 years 10 percent
Top of range [member] | Engineering equipment [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated Lives 10 years 30 percent
Top of range [member] | Office equipment [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated Lives 10 years 30 percent
Top of range [member] | Other [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated Lives 50 years 30 percent