Goodwill and Intangible Assets (Details) - CAD CAD in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill
Beginning Balance	CAD 198	CAD 164
Amortization	0	0
Foreign exchange impact	(7)	31
Additions		3
Ending Balance	191	198
Intangible assets
Cost, Beginning Balance	22	22
Accumulated amortization, Beginning Balance	(9)	(10)
Net carrying amounts, Beginning balance	13	12
Amortization	(1)	(1)
Foreign exchange impact	(1)	2
Cost, Ending Balance	22	22
Accumulated amortization, Ending Balance	(11)	(9)
Net carrying amounts, Ending balance	11	13
Total goodwill and intangible assets
Beginning Balance	211	176
Amortization	(1)	(1)
Foreign exchange impact	(8)	33
Additions		3
Ending Balance	CAD 202	CAD 211