OPERATING REVENUES - OTHER OPERATING REVENUES (Details) - Other operating revenues - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Operating Revenues
Other operating revenues	$ 8.5	$ 22.4
Late payment charges
Disaggregation of Operating Revenues
Other operating revenues	13.6	15.0
Alternative revenues
Disaggregation of Operating Revenues
Other operating revenues	(6.0)	6.2
Other
Disaggregation of Operating Revenues
Other operating revenues	$ 0.9	$ 1.2