SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION (Revenues from Product Sales and Services) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 534.1	$ 555.6	$ 743.2	$ 157.0	$ 696.3	$ 741.8	$ 714.3	$ 180.0	$ 1,989.9	$ 2,332.4	$ 1,866.0
Accounts Receivable, Allowance for Credit Loss	$ 0.0				$ 0.0				0.0	0.0	0.0
Product [Member]
Disaggregation of Revenue [Line Items]
Revenues									1,848.1	2,172.3	1,644.6
Freight [Member]
Disaggregation of Revenue [Line Items]
Revenues									141.8	160.1	166.7
Venture partners' cost reimbursements [Member]
Disaggregation of Revenue [Line Items]
Revenues									$ 0.0	$ 0.0	$ 54.7