CREDIT LOSSES - GROSS RECEIVABLES AND RELATED ALLOWANCES (Details) - Utility - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable and unbilled revenues	$ 237.7	$ 209.1
Allowance for credit losses	11.1	18.3	$ 4.2
Accounts receivable and unbilled revenues, net	226.6	190.8
Total accounts receivable, net - past due greater than 90 days	$ 8.0	$ 12.6
Past due greater than 90 days - collection risk mitigated by regulatory mechanisms	97.30%	94.40%
Amount of net accounts receivable with regulatory protections	$ 97.7
Percent of net accounts receivable with regulatory protections	43.10%