MEMBERS' EQUITY Narrative 1 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cash distributions, timing description	Our limited liability company agreement requires that, within 50 days after the end of each quarter, we distribute all of our available cash to the holders of record of our units on the applicable record date.
Pension and Other Postretirement Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax effect of Employee Transfer		$ 2.4