SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - INVENTORIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2017
Inventory [Line Items]
Natural gas	$ 92		$ 109
LNG	9		11
Materials and supplies	157		187
Inventories	258	[1]	307
SDG&E [Member]
Inventory [Line Items]
Natural gas	2		4
LNG	0		0
Materials and supplies	78		101
Inventories	80		105
SoCalGas [Member]
Inventory [Line Items]
LIFO liquidation	33
Natural gas	11		75
LNG	0		0
Materials and supplies	47		49
Inventories	58		124
Sempra South American Utilities [Member]
Inventory [Line Items]
Natural gas	0		0
LNG	0		0
Materials and supplies	27		30
Inventories	27		30
Sempra Mexico [Member]
Inventory [Line Items]
Natural gas	0		0
LNG	6		7
Materials and supplies	1		2
Inventories	7		9
Sempra Renewables [Member]
Inventory [Line Items]
Natural gas	0		0
LNG	0		0
Materials and supplies	4		5
Inventories	4		5
Sempra LNG & Midstream [Member]
Inventory [Line Items]
Natural gas	79		30
LNG	3		4
Materials and supplies	0		0
Inventories	$ 82		$ 34

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