DISPOSITIONS, ASSET IMPAIRMENT AND DISCONTINUED OPERATIONS (Consolidated Statements of Financial Position) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Current assets related to discontinued operations:
Cash and cash equivalents	$ 0.0	$ 7.4	$ 0.0	$ 18.0
Current assets related to discontinued operations, Total	0.0	138.6
Non-current assets related to discontinued operations:
Non-current assets related to discontinued operations, Total	0.0	4,775.3
Current liabilities related to discontinued operations:
Current liabilities related to discontinued operations, Total	0.0	299.8
Non-current liabilities related to discontinued operations:
Non-current liabilities related to discontinued operations, Total	$ 0.0	844.3
Discontinued Operations, Disposed of by Sale [Member]
Current assets related to discontinued operations:
Cash and cash equivalents		7.4
Restricted cash		11.0
Receivables, trade and other, net of allowance for doubtful accounts		8.5
Due from General Partner and affiliates		2.1
Accrued receivables		20.8
Inventory		28.1
Other current assets		60.7
Current assets related to discontinued operations, Total		138.6
Non-current assets related to discontinued operations:
Property, plant and equipment, net		4,114.5
Equity investment in joint venture		360.7
Intangible assets, net		251.8
Other assets, net		48.3
Non-current assets related to discontinued operations, Total		4,775.3
Current liabilities related to discontinued operations:
Accounts payable and other		66.9
Due to General Partner and affiliates		38.8
Environmental liabilities		0.1
Accrued purchases		171.8
Property and other taxes payable		17.2
Interest payable		5.0
Current liabilities related to discontinued operations, Total		299.8
Non-current liabilities related to discontinued operations:
Long-term debt		818.5
Other long-term liabilities		25.8
Non-current liabilities related to discontinued operations, Total		$ 844.3