Other Long-Term Liabilities (Details) - CAD CAD in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Liabilities Disclosure [Abstract]
Provision for environmental remediation, net of current portion	CAD 80	CAD 75
Stock-based compensation liabilities, net of current portion	73	145
Deferred revenue on rights-of-way licence agreements, net of current portion	33	33
Deferred retirement compensation	28	24
Deferred gains on sale leaseback transactions	22	25
Asset retirement obligations	22	23	CAD 24
Provision for restructuring, net of current portion	6	13
Deferred hedging losses	0	25
Other, net of current portion	54	69
Total other long-term liabilities	318	432
Aggregate provision for environmental remediation, including current portion	93	91
Aggregate provision for restructuring, including current portion	CAD 12	CAD 24	CAD 50	CAD 89