SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - CREDIT LOSSES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	$ 29	$ 21	$ 25
Provisions for expected credit losses	124	22	10
Write-offs	(16)	(14)	(14)
Allowances for credit losses at December 31	138	29	21
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1, 2020	0
Reduction to expected credit losses	(3)
Allowances for credit losses at December 31, 2020	3	0
Sempra LNG [Member]
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Maximum exposure of guarantor obligations	4,000
Reduction of credit loss liability	(4)
Accounts Receivable, Trade, Net [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	7
Allowances for credit losses at December 31	111	7
Accounts receivable – other, net [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	22
Allowances for credit losses at December 31	27	22
Due from Unconsolidated Affiliates - Noncurrent [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at December 31, 2020	3
Current liabilities: Other [Member] | Sempra LNG [Member]
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Liability for credit losses	2
Cumulative Effect, Period of Adoption, Adjustment
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	1	0	0
Allowances for credit losses at December 31		1	0
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1, 2020	6
Allowances for credit losses at December 31, 2020		6
Cumulative Effect, Period of Adoption, Adjustment | Sempra LNG [Member]
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Liability for credit losses		6
San Diego Gas and Electric Company [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	14	11	9
Provisions for expected credit losses	65	10	9
Write-offs	(10)	(7)	(7)
Allowances for credit losses at December 31	69	14	11
San Diego Gas and Electric Company [Member] | Accounts Receivable, Trade, Net [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	4
Allowances for credit losses at December 31	55	4
San Diego Gas and Electric Company [Member] | Accounts receivable – other, net [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	10
Allowances for credit losses at December 31	14	10
Southern California Gas Company [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	15	10	16
Provisions for expected credit losses	59	12	1
Write-offs	(6)	(7)	(7)
Allowances for credit losses at December 31	68	15	$ 10
Southern California Gas Company [Member] | Accounts Receivable, Trade, Net [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	3
Allowances for credit losses at December 31	55	3
Southern California Gas Company [Member] | Accounts receivable – other, net [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowances for credit losses at January 1	12
Allowances for credit losses at December 31	$ 13	$ 12