MATERIALS, SUPPLIES, AND INVENTORIES (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Inventory Disclosure [Abstract] | ||
| Materials and supplies | $ 101.2 | $ 101.8 |
| Fossil fuel | 32.9 | 40.7 |
| Natural gas in storage | 32.6 | 28.1 |
| Total | $ 166.7 | $ 170.6 |
| X | ||||||||||
- Definition Carrying amount as of the balance sheet date of merchandise, goods, commodities, or supplies relating to a source of usable power held for future sale or future use in manufacturing or production process. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Carrying amount as of the balance sheet date of natural gas in storage, which is a mixture of gases (liquefied or otherwise), used for fuel and manufacturing purposes, which is ready for sale. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of fossil fuel included in inventory classified as other. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Aggregated amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed. This amount is net of valuation reserves and adjustments. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|