Income Taxes - Deferred Income Tax Assets and Liabilities (Details) - CAD CAD in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred income tax assets
Restructuring liability	CAD 3	CAD 7
Amount related to tax losses carried forward	16	28
Liabilities carrying value in excess of tax basis	89	214
Future environmental remediation costs	33	32
Tax credits carried forward including minimum tax	0	20
Other	69	69
Total deferred income tax assets	210	370
Deferred income tax liabilities
Properties carrying value in excess of tax basis	3,553	3,052
Other	48	35
Total deferred income tax liabilities	3,601	3,087
Total net deferred income tax liabilities	CAD 3,391	CAD 2,717