SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - VARIABLE INTEREST ENTITIES (Details)		9 Months Ended	12 Months Ended
	Mar. 09, 2018	Oct. 03, 2019 MW	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Variable Interest Entity [Line Items]
Total finance leases			$ 1,330,000,000	$ 1,289,000,000
Property, plant and equipment, net			40,003,000,000	36,452,000,000
Equity method investment			12,440,000,000	11,519,000,000
Assets			66,623,000,000	65,665,000,000	$ 60,638,000,000
San Diego Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Total finance leases			1,276,000,000	1,270,000,000
Property, plant and equipment, net			18,421,000,000	16,967,000,000
Assets			22,311,000,000	20,560,000,000
San Diego Gas and Electric Company [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total finance leases			1,237,000,000	1,255,000,000
Property, plant and equipment, net			1,237,000,000	1,255,000,000
Sempra Energy [Member] | ECA LNG JV [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets			207,000,000
Liabilities			49,000,000
Sempra Mexico [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets				126,000,000
Sempra LNG [Member]
Variable Interest Entity [Line Items]
Debt instrument, maximum borrowing amount			4,000,000,000.0
Sempra LNG [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Debt instrument, maximum borrowing amount			979,000,000
Sempra LNG [Member] | Cameron LNG Holdings [Member]
Variable Interest Entity [Line Items]
Equity method investment			433,000,000	1,256,000,000
Oncor Electric Delivery Holdings Company LLC [Member] | Sempra Texas Utilities [Member]
Variable Interest Entity [Line Items]
Equity method investment			$ 12,440,000,000	$ 11,519,000,000
Sempra Texas Holdings Corp [Member] | Oncor Electric Delivery Holdings Company LLC [Member] | Sempra Texas Intermediate Holding Company LLC [Member]
Variable Interest Entity [Line Items]
Ownership percentage in consolidated entity	100.00%		100.00%
Sempra Texas Holdings Corp [Member] | Oncor Electric Delivery Company LLC [Member] | Sempra Texas Intermediate Holding Company LLC [Member]
Variable Interest Entity [Line Items]
Ownership percentage in consolidated entity	100.00%
Otay Mesa VIE [Member] | San Diego Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Generating capacity (in mw) | MW		605