ACQUISTION AND DIVESTITURE ACTIVITY - ACQUISITION ACTIVITY (Details) $ in Millions										1 Months Ended		3 Months Ended								12 Months Ended
	Jan. 12, 2018 USD ($)	Nov. 15, 2017 USD ($)	Oct. 03, 2017 USD ($)	Aug. 21, 2017 USD ($) director	Jul. 10, 2017 USD ($) ppa MW	Dec. 14, 2016 USD ($) MW	Oct. 13, 2016 USD ($)	Sep. 26, 2016 USD ($)	Jul. 01, 2016 USD ($) MW	Sep. 30, 2016 USD ($)	Mar. 31, 2015 USD ($) MW	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)		Nov. 14, 2017	Sep. 06, 2017 USD ($)	Sep. 25, 2016	Jan. 01, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Cash paid, net of cash and cash equivalents acquired																				$ (147.0)	$ (1,342.0)	[1]	$ (3.0)	[1]
Revenues																				11,207.0	10,183.0		10,231.0
Earnings/Income attributable to common shares												$ (501.0)	$ 57.0	$ 259.0	$ 441.0	$ 379.0	$ 622.0	$ 16.0	$ 353.0	256.0	1,370.0		1,349.0
Issuances of common stock																				47.0	51.0	[1]	52.0	[1]
Restricted cash												76.0				$ 76.0				76.0	$ 76.0
IEnova [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)							$ 351.0
Ventika [Member] | IEnova [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)							$ 50.0
Energy Future Holdings Corp. [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Consideration transferred				$ 9,450.0
Shares issued			$ 25.9
Percentage of consideration funded by equity issuance				65.00%
Percentage of consideration funded by debt issuance				35.00%
Plan percentage of capital structure allocated to debt				57.50%
Plan percentage of capital structure allocated to equity				42.50%
Transaction costs incurred												$ 43.0								$ 43.0
Number of directors on board | director				13
Fee receivable if agreement terminated																										$ 190.0
Sempra Mexico [Member] | IEnova [Member]
Business Acquisition [Line Items]
Ownership percentage held by noncontrolling owners												33.60%				33.60%				33.60%	33.60%							33.60%	18.90%
Sempra Mexico [Member] | Ramones Norte Pipeline [Member] | IEnova [Member]
Business Acquisition [Line Items]
Ownership percentage in equity method investee								25.00%
Sempra Mexico [Member] | Ductos Energéticos del Norte [Member] | IEnova [Member]
Business Acquisition [Line Items]
Acquired percentage interest		50.00%
Debt assumed		$ 96.0
Ownership percentage before acquisition		100.00%																							50.00%
Ownership percentage in consolidated entity		100.00%
Ownership percentage in equity method investee																									50.00%
Cash paid, net of cash and cash equivalents acquired		$ 165.0
Weighted average life of finite-lived intangible acquired		23 years
Cash Acquired from Acquisition		$ 18.0
Other intangible assets		$ 66.0
Sempra Mexico [Member] | Ductos Energéticos del Norte [Member] | Ramones Norte Pipeline [Member] | IEnova [Member]
Business Acquisition [Line Items]
Ownership percentage before acquisition		50.00%																							25.00%
Ownership percentage in consolidated entity		50.00%
Sempra Mexico [Member] | IEnova Pipelines [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)								$ 1,144.0
Cash and cash equivalents								66.0
Other intangible assets								$ 0.0
Sempra Mexico [Member] | IEnova Pipelines [Member] | IEnova [Member]
Business Acquisition [Line Items]
Acquired percentage interest								50.00%
Cash consideration (fair value of total consideration)								$ 1,144.0
Cash and cash equivalents								66.0
Debt assumed								$ 364.0
Ownership percentage before acquisition																											50.00%
Ownership percentage in consolidated entity								100.00%
Cash paid, net of cash and cash equivalents acquired								$ 1,078.0
Proceeds from debt issued								$ 1,150.0
Gain on acquisition of remaining voting rights										$ 617.0											$ 617.0
Gain on acquisition of remaining voting rights, net of tax										$ 432.0											432.0
Accrued Merger-related transaction costs																					4.0		$ 1.0
Revenues																					82.0
Earnings/Income attributable to common shares																					33.0
Sempra Mexico [Member] | Ventika [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)						$ 310.0
Cash and cash equivalents						0.0
Other intangible assets						$ 154.0
Sempra Mexico [Member] | Ventika [Member] | IEnova [Member]
Business Acquisition [Line Items]
Acquired percentage interest						100.00%
Debt assumed						$ 610.0
Proceeds from debt issued						250.0
Cash						10.0
Accrued Merger-related transaction costs																					1.0
Revenues																					4.0
Earnings/Income attributable to common shares																					$ 3.0
Consideration transferred						$ 310.0
Generating capacity (in mw) | MW						252
Power purchase agreement term						20 years
Issuances of common stock						$ 50.0
Restricted cash						$ 68.0
Sempra Mexico [Member] | Ventika [Member] | IEnova [Member] | Renewable energy and consumption permit [Member]
Business Acquisition [Line Items]
Weighted average life of finite-lived intangible acquired						19 years
Sempra Renewables [Member] | Great Valley Solar [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)					$ 124.0
Generating capacity (in mw) | MW					200
Number of purchase power agreements | ppa					4
Power purchase agreement term					18 years
Sempra Renewables [Member] | Huron County, Michigan [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)									$ 18.0							$ 4.0
Ownership percentage in consolidated entity									100.00%
Consideration transferred									$ 22.0
Generating capacity (in mw) | MW									100
Power purchase agreement term									15 years
Sempra Renewables [Member] | Stearns County, Minnesota [Member]
Business Acquisition [Line Items]
Ownership percentage in consolidated entity											100.00%
Consideration transferred											$ 8.0
Generating capacity (in mw) | MW											78
Power purchase agreement term											20 years
Oncor Holdings Electric Delivery Company LLC [Member] | Energy Future Holdings Corp. [Member] | Energy Future Intermediate Holding Company LLC [Member]
Business Acquisition [Line Items]
Ownership percentage in consolidated entity				100.00%
Energy Future Intermediate Holding Company LLC [Member] | Energy Future Holdings Corp. [Member] | Energy Future Holdings Corp. [Member]
Business Acquisition [Line Items]
Ownership percentage in consolidated entity				100.00%
Energy Future Holdings Corp. [Member] | Energy Future Holdings Corp. [Member]
Business Acquisition [Line Items]
Ownership percentage in consolidated entity				100.00%
Oncor Electric Delivery Company LLC. [Member] | Energy Future Holdings Corp. [Member]
Business Acquisition [Line Items]
Acquired percentage interest				80.03%
Oncor Electric Delivery Company LLC. [Member] | Energy Future Holdings Corp. [Member] | Texas Transmission Investment LLC [Member]
Business Acquisition [Line Items]
Ownership percentage held by noncontrolling owners				19.75%
Oncor Electric Delivery Company LLC. [Member] | Energy Future Holdings Corp. [Member] | Current and Former Directors and Officers of Oncor [Member]
Business Acquisition [Line Items]
Ownership percentage held by noncontrolling owners				0.22%
Independent Director [Member] | Energy Future Holdings Corp. [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Number of directors on board | director				7
Management [Member] | Energy Future Holdings Corp. [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Number of directors on board | director				2
Energy Future Intermediate Holding Company LLC [Member] | Director Appointed by Related Party [Member] | Energy Future Holdings Corp. [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Number of directors on board | director				2
Texas Transmission Investment LLC [Member] | Director Appointed by Related Party [Member] | Energy Future Holdings Corp. [Member] | Oncor Electric Delivery Company LLC. [Member]
Business Acquisition [Line Items]
Number of directors on board | director				2
Subsequent Event [Member] | Energy Future Holdings Corp. [Member]
Business Acquisition [Line Items]
Proceeds from issuance of debt	$ 4,900.0
Commercial paper [Member] | Subsequent Event [Member] | Energy Future Holdings Corp. [Member]
Business Acquisition [Line Items]
Proceeds from issuance of debt	$ 2,700.0

[1] As adjusted for the retrospective adoption of ASU 2016-15 and ASU 2016-18, which we discuss in Note 2.