Long-Term Debt - Summary of Long-Term Debt (Non-Printing) (Detail) CAD in Millions	6 Months Ended
	Jun. 30, 2017 CAD
2014 Senior Notes
Debt Instrument [Line Items]
Maturity Dates	Apr. 01, 2022
2015 Senior Notes
Debt Instrument [Line Items]
Maturity Dates	Jan. 12, 2022
Term Loan Facility
Debt Instrument [Line Items]
Maturity Dates	Feb. 17, 2024
Series 1 Notes | Senior notes
Debt Instrument [Line Items]
Aggregate principal amount of debt issued	CAD 35.6