Litigation, Commitments and Contingencies (Leases and Right-of-Way Obligations) (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Lessee, Lease, Description [Line Items]
2019	$ 61.8
2020	59.9
2021	59.0
2022	59.0
2023	43.2
Thereafter	9.4
Total minimum payments	292.3
Operating Leases, Rent Expense	$ 66.2	$ 69.8	$ 66.5
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	25 years