CREDIT LOSSES - GROSS RECEIVABLES AND RELATED ALLOWANCES (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Utility segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	$ 13.2	$ 11.7	$ 12.1	$ 11.1
Utility segment | Third-party receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable and unbilled revenues	277.4	279.5
Allowance for credit losses	13.2	11.7
Accounts receivable and unbilled revenues, net	264.2	267.8
Total accounts receivable, net - past due greater than 90 days	$ 11.7	$ 8.4
Past due greater than 90 days - collection risk mitigated by regulatory mechanisms	96.80%	95.50%
Amount of net accounts receivable with regulatory protections	$ 150.7
Percent of net accounts receivable with regulatory protections	57.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable and unbilled revenues	$ 0.0	$ 0.0