COMMITMENTS AND CONTINGENCIES - LEASES CASH FLOW INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Cash paid for operating leases	$ 79	$ 101
Cash paid for finance leases	173	173
Cash paid for finance leases	35	24
Increase (decrease) in operating lease obligations for right-of-use assets	20	585
Increase in finance lease obligations for investment in property, plant and equipment	77	38	$ 556
San Diego Gas and Electric Company [Member]
Lessee, Lease, Description [Line Items]
Cash paid for operating leases	31	33
Cash paid for finance leases	171	173
Cash paid for finance leases	23	18
Increase (decrease) in operating lease obligations for right-of-use assets	(1)	158
Increase in finance lease obligations for investment in property, plant and equipment	30	16	550
Southern California Gas Company [Member]
Lessee, Lease, Description [Line Items]
Cash paid for operating leases	24	27
Cash paid for finance leases	2	0
Cash paid for finance leases	12	6
Increase (decrease) in operating lease obligations for right-of-use assets	1	118
Increase in finance lease obligations for investment in property, plant and equipment	$ 47	$ 22	$ 6