XML 185 R128.htm IDEA: XBRL DOCUMENT v3.24.0.1
Fair Value of Financial Instruments and Risk Management - Derivatives (Narrative) (Details)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2023
CAD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
CAD ($)
Dec. 31, 2023
USD ($)
Nov. 30, 2023
CAD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Unrealized losses recognized in regulatory assets $ 4,384   $ 4,009    
Unrealized gains recognized as regulatory liabilities 3,958   3,915    
Unrealized gain (loss) on investments $ 8   (11)    
UNS Energy          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Realized gains shared with customers, percent 10.00% 10.00%      
Fortis | Unsecured Senior Notes, May Issuance, 2029 Maturity | Unsecured          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Face value $ 500       $ 500
Stated interest rate 4.43%     4.43% 5.68%
Energy contracts subject to regulatory deferral | Derivative instruments          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Unrealized gains recognized as regulatory liabilities $ 37   224    
Energy contracts subject to regulatory deferral | Derivative instruments          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Unrealized losses recognized in regulatory assets 197   84    
Energy contracts not subject to regulatory deferral          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Unrealized gain (loss) recognized in revenue (28)   34    
Total return swaps          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Notional amount of derivative 118        
Unrealized gain (loss) on total return swaps recognized in other income, net $ (1)   (22)    
Total return swaps | Minimum          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Derivative terms 1 year 1 year      
Total return swaps | Maximum          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Derivative terms 3 years 3 years      
Foreign exchange contracts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Notional amount of derivative $ 467        
Unrealized gain (loss) on total return swaps recognized in other income, net 10   (9)    
Interest rate locks | Fortis          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Notional amount of derivative $ 100        
Gain on derivative, reclassification adjustment period 10 years 10 years      
Realized gain recognized in other comprehensive income $ 8        
Interest rate locks | Fortis | Unsecured Senior Notes, November Issuance, 2023 Maturity          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Face value $ 500        
Interest rate locks | ITC          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Notional amount of derivative       $ 500  
Gain on derivative, reclassification adjustment period 10 years 10 years      
Realized gain recognized in other comprehensive income   $ 4      
Interest rate locks | ITC | Unsecured Senior Notes, June Issuance, 2023 Maturity | Unsecured          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Face value       500  
Cross currency interest rate swaps | Fortis          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Notional amount of derivative       $ 391  
Unrealized gain (loss) on total return swaps recognized in other income, net $ 15   $ (17)    
Interest rate 4.34%     4.34%