v3.25.0.1
Commitments and Contingencies - Fiscal Year Maturity (Details)
$ in Millions
 1 Months Ended 12 Months Ended
Apr. 30, 2015
Dec. 31, 2024
CAD ($)
GWh
agreement_renewal
agreement
MW
Purchase obligations:    
Total   $ 13,599
Year 1   1,634
Year 2   1,048
Year 3   926
Year 4   866
Year 5   782
Thereafter   8,343
Gas and fuel purchase obligations    
Purchase obligations:    
Total   6,299
Year 1   763
Year 2   571
Year 3   520
Year 4   465
Year 5   393
Thereafter   3,587
Gas and fuel purchase obligations | FortisBC Energy    
Purchase obligations:    
Total   5,014
Gas and fuel purchase obligations | UNS Energy    
Purchase obligations:    
Total   1,160
Renewable natural gas expiring 2044 | FortisBC Energy    
Purchase obligations:    
Total   2,792
Gas, renewable gas, gas transportation and storage services, expiring 2062 | FortisBC Energy    
Purchase obligations:    
Total   2,222
Renewable PPAs    
Purchase obligations:    
Total   2,628
Year 1   139
Year 2   166
Year 3   182
Year 4   182
Year 5   173
Thereafter   $ 1,786
Renewable PPAs | TEP and UNS Electric    
Purchase obligations:    
Share of plant output, percentage   100.00%
Waneta Expansion capacity agreement    
Purchase obligations:    
Total   $ 2,362
Year 1   56
Year 2   58
Year 3   59
Year 4   60
Year 5   61
Thereafter   2,068
Waneta Expansion capacity agreement | FortisBC Electric    
Purchase obligations:    
Purchase commitment term 40 years  
Power purchase obligations    
Purchase obligations:    
Total   1,335
Year 1   302
Year 2   217
Year 3   131
Year 4   124
Year 5   122
Thereafter   439
Power purchase obligations | FortisBC Electric    
Purchase obligations:    
Total   $ 301
Purchase commitment term   20 years
Power purchase obligations | FortisBC Electric | Maximum    
Purchase obligations:    
Amount of volume required (in mw) | MW   200
Volume of energy required to be purchased (in GWh) | GWh   1,752
Power purchase obligations | Maritime Electric    
Purchase obligations:    
Total   $ 563
Amount of volume required (in mw) | MW   30
Power purchase obligations | Maritime Electric | Nuclear Generating Station    
Purchase obligations:    
Share of plant output, percentage   4.55%
Power purchase obligations | FortisOntario    
Purchase obligations:    
Total   $ 374
Power purchase obligations | FortisOntario | Maximum    
Purchase obligations:    
Amount of volume required (in mw) | MW   145
Power purchase obligations | FortisOntario | Minimum    
Purchase obligations:    
Volume of energy required to be purchased (in GWh) | GWh   537
ITC easement agreement    
Purchase obligations:    
Total   $ 370
Year 1   14
Year 2   14
Year 3   14
Year 4   14
Year 5   14
Thereafter   $ 300
ITC easement agreement | ITC    
Purchase obligations:    
Number of agreement renewals | agreement_renewal   10
Agreement renewal term   50 years
Notice, period in advance   1 year
TEP EPC agreements    
Purchase obligations:    
Total   $ 308
Year 1   307
Year 2   1
Year 3   0
Year 4   0
Year 5   0
Thereafter   $ 0
Number of engineering, procurement and construction agreements | agreement   2
Debt collection agreement    
Purchase obligations:    
Total   $ 99
Year 1   3
Year 2   3
Year 3   3
Year 4   3
Year 5   3
Thereafter   84
Renewable energy credit purchase agreements    
Purchase obligations:    
Total   58
Year 1   18
Year 2   7
Year 3   6
Year 4   6
Year 5   6
Thereafter   15
Other    
Purchase obligations:    
Total   140
Year 1   32
Year 2   11
Year 3   11
Year 4   12
Year 5   10
Thereafter   $ 64