v3.26.1
INVESTMENT IN TRANSMISSION AFFILIATES - RELATED PARTY TRANSACTIONS (Details) - ATC - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Investment in transmission affiliates        
Charges to ATC for services and construction $ 6.1 $ 5.0 $ 13.4 $ 9.5
Charges from ATC for network transmission services 129.0 116.7 258.2 233.4
Net refund (payment) from (to) ATC related to FERC ROE orders $ (0.7) $ 0.3 $ 1.3 $ 1.7