DEBT (Interest Cost) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Interest Cost
Interest cost incurred	[1]	$ 122.0	$ 60.5
Less: Interest capitalized		9.1	12.2
Interest expense		$ 112.9	$ 48.3

[1] Interest cost incurred increased period-over-period, due to an increase in our average outstanding debt balances outstanding and in part due to a decrease in unrealized losses for the three months ended March 31, 2015, that did not occur during the same period in 2016.