REVENUES - Receivables From Revenues From Contracts With Customers (Details) - USD ($) $ in Millions	Mar. 31, 2018	Jan. 01, 2018
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	$ 1,246	$ 1,212
Accounts receivable – trade, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	1,226	1,194
Accounts receivable – other, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	11	10
Due from unconsolidated affiliates – current [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	9	8
San Diego Gas and Electric Company [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	385	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	376	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	512	524
Southern California Gas Company [Member] | Accounts receivable – trade, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	509	517
Southern California Gas Company [Member] | Accounts receivable – other, net [Member]
Contract with Customer, Asset [Line Items]
Receivables from revenues from contracts with customers	$ 3	$ 7