Annual report pursuant to Section 13 and 15(d)

Income Tax - Summary of Years Open to Examination under Different Jurisdiction (Detail)

v3.19.1
Income Tax - Summary of Years Open to Examination under Different Jurisdiction (Detail)
 12 Months Ended
Dec. 31, 2018
Earliest Tax Year [Member] | Canada [Member] | Canada  
Income Tax Examination [Line Items]  
Years open to examination 2010
Earliest Tax Year [Member] | Canada [Member] | UK  
Income Tax Examination [Line Items]  
Years open to examination 2011
Earliest Tax Year [Member] | US [Member]  
Income Tax Examination [Line Items]  
Years open to examination 2010
Latest Tax Year [Member] | Canada [Member] | Canada  
Income Tax Examination [Line Items]  
Years open to examination 2018
Latest Tax Year [Member] | Canada [Member] | UK  
Income Tax Examination [Line Items]  
Years open to examination 2018
Latest Tax Year [Member] | US [Member]  
Income Tax Examination [Line Items]  
Years open to examination 2018