CREDIT LOSSES - GROSS RECEIVABLES AND RELATED ALLOWANCES (Details) - USD ($) $ in Millions	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Utility segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable and unbilled revenues	$ 242.8		$ 233.7
Allowance for credit losses	7.4	$ 7.5	8.6	$ 8.3	$ 9.6	$ 10.9
Accounts receivable and unbilled revenues, net	235.4		225.1
Total accounts receivable, net - past due greater than 90 days	$ 6.4		$ 7.4
Past due greater than 90 days - collection risk mitigated by regulatory mechanisms	94.60%		93.90%
Amount of net accounts receivable with regulatory protections	$ 113.3
Percent of net accounts receivable with regulatory protections	48.10%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable and unbilled revenues	$ 0.0		$ 0.0