OTHER CONTINGENCIES AND COMMITMENTS (Disallowance of Plant Costs) (Details) - USD ($) $ in Millions		12 Months Ended	48 Months Ended
	Jun. 23, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2014
Disallowance of Plant Costs
Loss Contingencies [Line Items]
Gas transmission and storage capital disallowance	$ 696
Permanently disallowed capital	120
Amount subject to audit	$ 576
Capital expenditure charges		$ 219
2011-2014
Loss Contingencies [Line Items]
Gas transmission and storage capital disallowance				$ 134
2015-2018
Loss Contingencies [Line Items]
Gas transmission and storage capital disallowance			$ 44