SUPPLEMENTAL CASH FLOW INFORMATION - SUPPLEMENTAL INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2019	Sep. 30, 2018
Supplemental cash flow information
Cash (paid) for interest, net of amount capitalized				$ (317.9)	$ (278.1)
Cash (paid) for income taxes, net				(15.4)	(55.9)
Significant non-cash investing and financing transactions
Accounts payable related to construction costs				162.7	71.9
Non-cash capital contributions from noncontrolling interest	$ 4.3	$ 5.5	$ 4.8	$ 14.6	$ 0.0

Future cash outflow to pay for purchases of fixed assets that have occurred.

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