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Financial Risk Management - Credit Risk (Details)
CAD in Millions
12 Months Ended
Dec. 31, 2016
CAD
FortisAlberta | Credit risk exposure  
Concentration Risk [Line Items]  
Gross credit risk exposure CAD 123
Retailer billings (over) (period) 37 days
Reduction in credit risk exposure due to deposit, bond, letter of credit, inv grade credit rating or other guarantee CAD 1
Revenue | Three Customers | Customer Concentration Risk  
Concentration Risk [Line Items]  
Concentration risk percentage 70.00%