COMMITMENTS AND CONTINGENCIES - FUTURE MINIMUM LEASE PAYMENTS UNDER TOPIC 840 (Details) $ in Millions	Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
2019	$ 215
2020	210
2021	211
2022	211
2023	211
Thereafter	3,196
Total undiscounted lease payments	4,254
2019	77
2020	55
2021	53
2022	50
2023	42
Thereafter	253
Total undiscounted lease payments	530
Less: estimated executory costs	(480)
Less: imputed interest	(2,483)
Total future minimum lease payments	1,291
HQ Build To Suit Arrangement [Member]
Operating Leased Assets [Line Items]
2019	10
2020	11
2021	11
2022	11
2023	11
Thereafter	217
Total undiscounted lease payments	271
Southern California Gas Company [Member]
Operating Leased Assets [Line Items]
2019	3
2020	0
2021	0
2022	0
2023	0
Thereafter	0
Total undiscounted lease payments	3
2019	26
2020	22
2021	21
2022	20
2023	16
Thereafter	28
Total undiscounted lease payments	133
Less: estimated executory costs	0
Less: imputed interest	0
Total future minimum lease payments	3
San Diego Gas and Electric Company [Member]
Operating Leased Assets [Line Items]
2019	212
2020	210
2021	211
2022	211
2023	211
Thereafter	3,196
Total undiscounted lease payments	4,251
2019	23
2020	22
2021	22
2022	21
2023	17
Thereafter	48
Total undiscounted lease payments	153
Less: estimated executory costs	(480)
Less: imputed interest	(2,483)
Total future minimum lease payments	$ 1,288