ESTIMATES, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND BALANCE SHEET DETAIL Estimates, Significant Accounting Policies and Balance Sheet Detail - PPE (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Interest Costs Capitalized		$ 1	$ 3	$ 2
Property, Plant and Equipment, Gross	$ 3,199	3,196	3,199
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	419	507	419
Net property, plant and equipment	2,780	$ 2,689	2,780
Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P6Y0M
Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P46Y0M
Pipelines And Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P5Y0M
Pipelines And Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P46Y0M
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3	$ 3	3
Construction Work-In-Process [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	27	37	27
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	162	158	162
Pipelines [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,571	2,556	2,571
Natural Gas, Storage [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	279	$ 282	279
Natural Gas, Storage [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P26Y0M
Natural Gas, Storage [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P46Y0M
Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	157	$ 160	157
Property, Plant and Equipment, Other Types [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P3Y0M
Property, Plant and Equipment, Other Types [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives		P21Y0M
Sea Robin [Member]
Property, Plant and Equipment [Line Items]
Tangible Asset Impairment Charges	$ 127		$ 133