ACQUISTION AND DIVESTITURE ACTIVITY - ASSETS ACQUIRED AND LIABILITIES ASSUMED (Details) - USD ($) $ in Millions			3 Months Ended			12 Months Ended
	Dec. 14, 2016	Sep. 26, 2016	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Business Acquisition [Line Items]
Fair value of equity interest in IEnova Pipelines immediately prior to acquisition						$ 28	$ 1,144	[1]	$ 0	[1]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Goodwill			$ 2,397	$ 2,364	[2]	2,397	2,364	[2]	$ 819
Acquisition of business – measurement period adjustment						(13)
Sempra Mexico [Member] | IEnova Pipelines [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)		$ 1,144
Fair value of equity interest in IEnova Pipelines immediately prior to acquisition		1,144
Total fair value of business combination		2,288
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and cash equivalents		66
Restricted cash		0
Accounts receivable		39
Other current assets		6
Other intangible assets		0
Deferred income taxes		0
Regulatory assets		33
Property, plant and equipment		1,248
Other noncurrent assets		1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Short-term debt		0
Accounts payable		(11)
Due to unconsolidated affiliates		(3)
Current portion of long-term debt		(49)
Fixed-price contracts and other derivatives, current		(6)
Other current liabilities		(20)
Long-term debt		(315)
Asset retirement obligations		(5)
Deferred income taxes		(127)
Fixed-price contracts and other derivatives, noncurrent		(19)
Other noncurrent liabilities		(11)
Total identifiable net assets		827
Goodwill		$ 1,461
Sempra Mexico [Member] | IEnova Pipelines [Member] | Scenario, Adjustment [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Regulatory assets				33			33
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Deferred income taxes				(119)			$ (119)
Acquisition of business – measurement period adjustment				$ 86
Sempra Mexico [Member] | Ventika [Member]
Business Acquisition [Line Items]
Cash consideration (fair value of total consideration)	$ 310
Fair value of equity interest in IEnova Pipelines immediately prior to acquisition	0
Total fair value of business combination	310
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and cash equivalents	0
Restricted cash	68
Accounts receivable	14
Other current assets	1
Other intangible assets	154
Deferred income taxes	36
Regulatory assets	0
Property, plant and equipment	673
Other noncurrent assets	3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Short-term debt	(125)
Accounts payable	(1)
Due to unconsolidated affiliates	0
Current portion of long-term debt	(7)
Fixed-price contracts and other derivatives, current	(4)
Other current liabilities	(8)
Long-term debt	(478)
Asset retirement obligations	(2)
Deferred income taxes	(120)
Fixed-price contracts and other derivatives, noncurrent	(10)
Other noncurrent liabilities	0
Total identifiable net assets	194
Goodwill	$ 116
Sempra Mexico [Member] | Ventika [Member] | Scenario, Adjustment [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Deferred income taxes			13			$ 13
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Acquisition of business – measurement period adjustment			$ (13)

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

[2] Reflects reclassifications to conform to current year presentation, which we discuss in Note 1.