Accounts Payable and Accrued Liabilities (Details) - CAD CAD in Millions	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Trade payables	CAD 352	CAD 339
Accrued charges	282	293
Income and other taxes payable	146	218
Accrued interest	137	147
Derivative Liability, Current	69	60
Payroll-related accruals	73	88
Accrued vacation	65	69
Dividends payable	73	53
Personal injury and other claims provision	26	30
Provision for environmental remediation	9	13
Stock-based compensation liabilities	40	48
Other	50	59
Total accounts payable and accrued liabilities	CAD 1,322	CAD 1,417