SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Summary of Significant Accounting Policies - PPE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 3,199	$ 3,242
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	419	355
Net property, plant and equipment	2,780	2,887
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3	3
Construction Work-In-Process [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	27	54
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	162	174
Pipelines [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,571	2,540
Natural Gas Storage [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	279	277
Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	157	194
Sea Robin [Member]
Property, Plant and Equipment [Line Items]
Tangible Asset Impairment Charges	$ 127	$ 133