COMMITMENTS AND CONTINGENCIES - LEASES (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($) facility
Lessee, Lease, Description [Line Items]
Lease term	12 months
Number of battery storage facilities | facility	3
Leases not yet commenced, future minimum lease payments, 2020 - 2024	$ 1
Leases not yet commenced, future minimum lease payments, thereafter	18
Aggregate maximum lease limit	187
San Diego Gas and Electric Company [Member]
Lessee, Lease, Description [Line Items]
Aggregate maximum lease limit, utilized	53
Southern California Gas Company [Member]
Lessee, Lease, Description [Line Items]
Aggregate maximum lease limit, utilized	$ 75
Minimum [Member]
Lessee, Lease, Description [Line Items]
Termination period	1 year
Annual increase in rent	1.00%
Maximum [Member]
Lessee, Lease, Description [Line Items]
Option to extend terms	25 years
Annual increase in rent	5.00%