OPERATING REVENUES - OTHER OPERATING REVENUES (Details) - Other operating revenues - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Operating Revenues
Other operating revenues	$ 20.0	$ 6.7	$ 49.9	$ 15.2
Late payment charges
Disaggregation of Operating Revenues
Other operating revenues	16.2	16.3	33.4	29.9
Alternative revenues
Disaggregation of Operating Revenues
Other operating revenues	2.1	(11.3)	13.9	(17.3)
Other
Disaggregation of Operating Revenues
Other operating revenues	$ 1.7	$ 1.7	$ 2.6	$ 2.6