GENERAL INFORMATION AND OTHER FINANCIAL DATA - DUE TO DUE FROM AFFILIATES (Details) $ in Billions	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)		Mar. 31, 2018 MXN ($)
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - current	$ 63,000,000	$ 37,000,000	[1]
Due from unconsolidated affiliates - noncurrent	666,000,000	598,000,000	[1]
Due to unconsolidated affiliates, current	(6,000,000)	(7,000,000)	[1]
Due to Affiliate, Noncurrent	$ (35,000,000)	(35,000,000)	[1]
ESJ joint venture [Member] | LIBOR [Member]
Related Party Transaction [Line Items]
Spread on variable rate	637.50%
Interest rate on due from affiliate, noncurrent	8.26%
TAG Pipeline Norte [Member]
Related Party Transaction [Line Items]
Interest rate on due from affiliate, noncurrent	5.35%
TAG Pipeline Norte [Member] | LIBOR [Member]
Related Party Transaction [Line Items]
Spread on variable rate	290.00%
San Diego Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Due to unconsolidated affiliates, current	$ (43,000,000)	(40,000,000)	[1]
Maximum borrowing capacity	750,000,000
San Diego Gas and Electric Company [Member] | Due to/from Other affiliates [Member]
Related Party Transaction [Line Items]
Due to unconsolidated affiliates, current	(6,000,000)	(6,000,000)
San Diego Gas and Electric Company [Member] | Due to/from Sempra Energy [Member]
Related Party Transaction [Line Items]
Due to unconsolidated affiliates, current	(32,000,000)	(30,000,000)
Income taxes due (to) from Sempra Energy	(39,000,000)	27,000,000
San Diego Gas and Electric Company [Member] | Due to/from SoCalGas [Member]
Related Party Transaction [Line Items]
Due to unconsolidated affiliates, current	(5,000,000)	(4,000,000)
Southern California Gas Company [Member]
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - current	6,000,000	4,000,000	[1]
Due to unconsolidated affiliates, current	(37,000,000)	(35,000,000)	[1]
Maximum borrowing capacity	750,000,000
Southern California Gas Company [Member] | Due to/from Other affiliates [Member]
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - current	1,000,000	0
Southern California Gas Company [Member] | Due to/from Sempra Energy [Member]
Related Party Transaction [Line Items]
Due to unconsolidated affiliates, current	(37,000,000)	(35,000,000)
Income taxes due (to) from Sempra Energy	(2,000,000)	10,000,000
Southern California Gas Company [Member] | Due to/from SDG&E [Member]
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - current	5,000,000	4,000,000
Sempra South American Utilities [Member] | Eletrans [Member]
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - noncurrent	$ 38,000,000	103,000,000
Interest rate on due from affiliate, noncurrent	4.00%
Sempra South American Utilities [Member] | Due to/from Other affiliates [Member]
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - noncurrent	$ 1,000,000	1,000,000
Sempra Mexico [Member] | IMG [Member]
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - noncurrent	621,000,000	487,000,000
Maximum borrowing capacity	$ 777,000,000			$ 14.2
Sempra Mexico [Member] | IMG [Member] | Interbank Equilibrium Rate [Member]
Related Party Transaction [Line Items]
Spread on variable rate	220.00%
Interest rate on due from affiliate, noncurrent	10.07%
Sempra Mexico [Member] | ESJ joint venture [Member]
Related Party Transaction [Line Items]
Due from unconsolidated affiliates - noncurrent	$ 6,000,000	7,000,000
Sempra Mexico [Member] | TAG Pipeline Norte [Member]
Related Party Transaction [Line Items]
Due to Affiliate, Noncurrent	$ (35,000,000)	$ (35,000,000)

[1] Derived from audited financial statements.