ACQUISTION AND DIVESTITURE ACTIVITY - ACQUISITION ACTIVITY (Details) $ in Millions						1 Months Ended	3 Months Ended
	Mar. 09, 2018 USD ($)	Mar. 08, 2018 USD ($) shares	Feb. 28, 2018 USD ($) MW	Jan. 12, 2018 USD ($)	Jan. 09, 2018 shares	Jan. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	[1]
Business Acquisition [Line Items]
Cash paid, net of cash and cash equivalents acquired							$ (9,566)	$ 0
Repayments of debt				$ 800		$ 800
Issuances of common stock, net of $24 in offering costs							$ 1,278	$ 17
Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Acquired percentage interest	80.25%
Oncor Holdings [Member]
Business Acquisition [Line Items]
Consideration	$ 9,566
Fisterra Midstream Mexico [Member] | Sempra Mexico [Member]
Business Acquisition [Line Items]
Cash consideration			$ 5
Commitment to Invest			$ 130
Generating capacity (in mw) | MW			125
Term of power purchase agreement			15 years
Oncor Electric Delivery Company LLC Additional Acquisition [Member] | Sempra Texas Intermediate Holding Company LLC [Member] | Oncor Holdings [Member]
Business Acquisition [Line Items]
Cash consideration	$ 26
Oncor Electric Delivery Company LLC Additional Acquisition [Member] | Oncor Electric Delivery Company LLC. [Member] | Oncor Holdings [Member]
Business Acquisition [Line Items]
Acquired percentage interest	0.22%
Ownership percentage in consolidated entity	0.22%
Consideration	$ 26
Sempra Texas Holdings Corp [Member]
Business Acquisition [Line Items]
Proceeds from Issuance of Debt and Equity						$ 7,000
Proceeds from issuance of debt				$ 4,900
Sempra Texas Holdings Corp [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Acquired percentage interest	80.03%
Sempra Texas Holdings Corp [Member] | Sempra Texas Intermediate Holding Company LLC [Member] | Oncor Holdings [Member]
Business Acquisition [Line Items]
Ownership percentage in consolidated entity	100.00%
Sempra Texas Holdings Corp [Member] | Texas Transmission Investment LLC [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Ownership percentage held by noncontrolling owners	19.75%
Sempra Texas Holdings Corp [Member] | Oncor Holdings [Member]
Business Acquisition [Line Items]
Cash consideration	$ 9,450
Adjustment for dividends	31
Transaction costs incurred	$ 59
Sempra Texas Holdings Corp [Member] | Oncor Holdings [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Ownership percentage in consolidated entity	80.25%
Common Stock [Member]
Business Acquisition [Line Items]
Shares issued | shares		8,556,630			26,869,158
Common Stock [Member] | Settlement of Forward Sale Contracts [Member]
Business Acquisition [Line Items]
Issuances of common stock, net of $24 in offering costs		$ 900
Commercial Paper [Member] | Sempra Texas Holdings Corp [Member] | Oncor Holdings [Member]
Business Acquisition [Line Items]
Proceeds from issuance of debt		$ 2,600
Weighted average maturity		47 days
Weighted average interest rate		2.20%

[1] As adjusted for the retrospective adoption of ASU 2016-18, which we discuss in Note 2.