REVENUES - RECEIVABLES FROM REVENUES FROM CONTRACTS WITH CUSTOMERS (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jan. 01, 2018
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	$ 1,148	$ 1,212
Accounts receivable – trade, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	1,121	1,194
Accounts receivable – other, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	13	10
Due from unconsolidated affiliates – current [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	4	8
Assets held-for-sale [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	10	0
San Diego Gas and Electric Company [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	479	368
San Diego Gas and Electric Company [Member] | Accounts receivable – trade, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	470	362
San Diego Gas and Electric Company [Member] | Accounts receivable – other, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	6	3
San Diego Gas and Electric Company [Member] | Due from unconsolidated affiliates – current [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	3	3
Southern California Gas Company [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	349	524
Southern California Gas Company [Member] | Accounts receivable – trade, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	342	517
Southern California Gas Company [Member] | Accounts receivable – other, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	$ 7	$ 7