Other Long-Term Liabilities (Details) - CAD CAD in Millions	Dec. 31, 2016	Dec. 31, 2015
Other Liabilities Disclosure [Abstract]
Provision for environmental remediation, net of current portion	CAD 76	CAD 80
Stock-based compensation liabilities, net of current portion	72	73
Deferred revenue on rights-of-way licence agreements, net of current portion	29	33
Deferred retirement compensation	29	28
Deferred gains on sale leaseback transactions	19	22
Other, net of current portion	59	82
Total other long-term liabilities	284	318
Aggregate provision for environmental remediation, including current portion	CAD 85	CAD 93