SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash and Cash Equivalents [Abstract]
Cash (paid) for interest, net of amount capitalized	$ (27.5)	$ (29.2)
Cash received for income taxes, net	48.8	13.2
Accounts payable related to construction costs	$ 42.2	$ 74.9