SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Cash (paid) for interest, net of amount capitalized	$ (56.6)	$ (53.0)
Cash received (paid) for income taxes, net	8.9	(0.4)
Accounts payable related to construction costs	116.4	90.1
Increase (decease) in restricted cash from the sale (purchase) of investments held in the rabbi trust	8.3	(1.5)
Portion of Bostco real estate holdings sale financed with note receivable	7.0	0.0
Amortization of deferred revenue	6.2	$ 6.2
Long-term restricted cash	$ 26.9		$ 33.6