DISPOSITIONS, ASSET IMPAIRMENT AND DISCONTINUED OPERATIONS (Consolidated Statements of Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating expenses:
Net loss from discontinued operations	$ 0.0	$ (31.1)	$ (56.8)	$ (124.4)
Discontinued Operations, Disposed of by Sale [Member]
Operating revenues:
Operating revenues	0.0	486.0	1,161.1	1,345.5
Operating expenses:
Commodity costs	0.0	396.1	968.2	1,082.0
Operating and administrative	0.0	36.6	64.7	111.4
Depreciation and amortization	0.0	39.2	74.5	118.7
Asset impairment	0.0	0.0	0.0	10.6
Operating expenses, Total	0.0	515.6	1,218.2	1,464.4
Operating loss	0.0	(29.6)	(57.1)	(118.9)
Interest expense, net	0.0	(9.0)	(17.4)	(25.5)
Other income	0.0	8.1	18.6	22.0
Loss before income taxes	0.0	(30.5)	(55.9)	(122.4)
Income tax expense	0.0	(0.6)	(0.9)	(2.0)
Net loss from discontinued operations	0.0	(31.1)	(56.8)	(124.4)
Discontinued Operations, Disposed of by Sale [Member] | Commodity sales - nonaffiliate [Member]
Operating revenues:
Operating revenues	0.0	440.7	1,085.0	1,197.9
Discontinued Operations, Disposed of by Sale [Member] | Commodity sales - affiliate [Member]
Operating revenues:
Operating revenues	0.0	1.3	9.4	7.9
Discontinued Operations, Disposed of by Sale [Member] | Transportation and other services - nonaffiliate [Member]
Operating revenues:
Operating revenues	0.0	44.0	66.7	139.7
Discontinued Operations, Disposed of by Sale [Member] | Commodity costs - affiliate [Member]
Operating expenses:
Commodity costs	0.0	7.9	42.1	29.1
Discontinued Operations, Disposed of by Sale [Member] | Operating and administrative - affiliate [Member]
Operating expenses:
Operating and administrative	$ 0.0	$ 35.8	$ 68.7	$ 112.6