Income Taxes Deferred Tax Assets and Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets
Non capital losses	$ 0.1	$ 0.0
Reserves	35.8	43.0
Capital losses	0.2	27.2
Investment in partnerships	144.4	117.4
Valuation allowances	(144.6)	(144.5)
Total deferred tax assets	35.9	43.1
Deferred tax liabilities
Property, plant, and equipment	(36.0)	(392.0)
Total deferred tax liabilities	(36.0)	(392.0)
Net non-current deferred tax liability	$ (0.1)	$ (348.9)