v3.26.1
INVESTMENT IN TRANSMISSION AFFILIATES - SUMMARIZED FINANCIAL DATA (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Summarized financial data          
Operating revenues $ 2,062.1 $ 2,009.5 $ 5,496.3 $ 5,159.0  
Operating expenses 1,629.3 1,604.6 4,083.5 3,816.6  
Other expense, net 104.8 142.4 225.6 293.7  
Current assets 2,781.8   2,781.8   $ 3,284.7
Noncurrent assets 49,968.6   49,968.6   48,233.6
Total assets 52,750.4 48,524.3 52,750.4 48,524.3 51,518.3
Current liabilities 5,208.4   5,208.4   5,593.4
Long-term debt 19,216.3   19,216.3   18,498.1
Other noncurrent liabilities 951.9   951.9   963.4
Total liabilities and members' equity 52,750.4   52,750.4   51,518.3
ATC          
Summarized financial data          
Operating revenues 274.0 241.2 539.3 476.1  
Operating expenses 129.6 117.6 257.0 234.3  
Other expense, net 44.7 42.7 88.5 81.8  
Net income 99.7 $ 80.9 193.8 $ 160.0  
Current assets 163.9   163.9   137.5
Noncurrent assets 8,139.8   8,139.8   7,590.8
Total assets 8,303.7   8,303.7   7,728.3
Current liabilities 620.5   620.5   839.8
Long-term debt 3,576.0   3,576.0   3,156.3
Other noncurrent liabilities 782.0   782.0   638.9
Members' equity 3,325.2   3,325.2   3,093.3
Total liabilities and members' equity $ 8,303.7   $ 8,303.7   $ 7,728.3