OPERATING REVENUES - DISAGGREGATION OF ELECTRIC UTILITY OPERATING REVENUES BY CUSTOMER CLASS (Details) - Revenues from contracts with customers - Utility segment - Transferred over time - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2026

Jun. 30, 2025

Jun. 30, 2026

Jun. 30, 2025

Disaggregation of Operating Revenues

Revenues from contracts with customers

$ 1,042.9

$ 1,006.1

$ 2,356.7

$ 2,182.2

Electric

Disaggregation of Operating Revenues

Revenues from contracts with customers

963.8

921.3

1,979.5

1,856.6

Electric | Total retail

Disaggregation of Operating Revenues

Revenues from contracts with customers

912.5

853.3

1,835.2

1,712.8

Electric | Residential

Disaggregation of Operating Revenues

Revenues from contracts with customers

394.6

382.4

815.1

784.3

Electric | Small commercial and industrial

Disaggregation of Operating Revenues

Revenues from contracts with customers

325.0

306.3

654.0

613.2

Electric | Large commercial and industrial

Disaggregation of Operating Revenues

Revenues from contracts with customers

188.1

159.7

355.7

304.7

Electric | Other

Disaggregation of Operating Revenues

Revenues from contracts with customers

4.8

4.9

10.4

10.6

Electric | Wholesale

Disaggregation of Operating Revenues

Revenues from contracts with customers

11.8

10.9

26.2

25.0

Electric | Resale

Disaggregation of Operating Revenues

Revenues from contracts with customers

32.2

49.9

95.8

98.5

Electric | Steam

Disaggregation of Operating Revenues

Revenues from contracts with customers

5.4

5.2

19.2

17.7

Electric | Other utility

Disaggregation of Operating Revenues

Revenues from contracts with customers

$ 1.9

$ 2.0

$ 3.1

$ 2.6