XML 110 R93.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes (Unrecognized Benefits) (Details) - CAD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]    
Beginning, January 1 $ 18 $ 6
Increases due to tax positions related to current year 1 12
Balance, December 31 $ 19 $ 18