REGULATORY MATTERS (Cost Recovery Mechanisms) (Details) $ in Millions	1 Months Ended			12 Months Ended
	Feb. 28, 2017 $ / kWh	May 31, 2016 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2025	Dec. 31, 2020	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) $ / kWh	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Months approved rate in effect unless modified							12 months
Months of preceding period for true up component							12 months
Over-Recovered Costs for Purchased Power and Fuel							$ 38	$ 18
Renewable Energy Program [Member]
Public Utilities, General Disclosures [Line Items]
Renewable Energy Target Percentage							6.00%
Approved Spending Budget		$ 57
Approved Carryover of Unused Funds		9
Approved Recovery of Spending Budget		$ 48
Recovery Revenue							$ 3
Renewable Energy Actual Percentage							10.00%
Renewable Energy Program [Member] | Scenario, Forecast [Member]
Public Utilities, General Disclosures [Line Items]
Renewable Energy Target Percentage				15.00%
Distributed Generation Requirement Target Percentage				30.00%
Recovery Revenue						$ 1
Renewable Energy Budget Spending						$ 54
Energy Efficiency Standards [Member]
Public Utilities, General Disclosures [Line Items]
Approved Recovery of Spending Budget			$ 14
Percentage of Cumulative Annual Retail Kilowatt Savings, Actual							12.00%
Energy Efficiency Standards [Member] | Scenario, Forecast [Member]
Public Utilities, General Disclosures [Line Items]
Percentage of Electric Energy Efficiency Standards Target Retail Savings on Sales					22.00%
Demand Side Management - Energy Efficiency Standards [Member]
Public Utilities, General Disclosures [Line Items]
Recovery Revenue							$ 2	3	$ 2
Lost Fixed Cost Recovery Mechanism - Energy Efficiency Standards [Member]
Public Utilities, General Disclosures [Line Items]
Recovery Revenue							$ 18	$ 12	$ 11
Cap on Increase in Lost Fixed Cost Recovery Rate							1.00%
Effective May 2016 through February 2017 [Member] | Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Purchased Power And Fuel Adjustment Clause Rate [cents per kwh] | $ / kWh							0.0015
Effective April 2015 through March 2016 [Member] | Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Purchased Power And Fuel Adjustment Clause Rate [cents per kwh] | $ / kWh							0.0068
Effective October 2014 through March 2015 [Member] | Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Purchased Power And Fuel Adjustment Clause Rate [cents per kwh] | $ / kWh							0.0050
Effective May 2014 through September 2014 [Member] | Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Purchased Power And Fuel Adjustment Clause Rate [cents per kwh] | $ / kWh							0.0010
Effective July 2013 through April 2014 [Member] | Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Purchased Power And Fuel Adjustment Clause Rate [cents per kwh] | $ / kWh							(0.0014)
Subsequent Event [Member] | Effective March 2017 through March 2018 [Member] | Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Purchased Power And Fuel Adjustment Clause Rate [cents per kwh] | $ / kWh	(0.0020)