GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	$ 448		$ 250
Accumulated amortization	(51)		(48)
Net intangible assets	397		202
Amortization expense	3	$ 3
Future amortization expense per year	20
Expected amortization charged against revenue	11
Future amortization expense, per year, next four years	26
Expected amortization expense, recorded in revenue, next four years	14
Renewable energy transmission and consumption permit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	169		169
Accumulated amortization	$ (34)		(32)
Renewable energy transmission and consumption permit [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	15 years
Renewable energy transmission and consumption permit [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	19 years
O&M agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	23 years
Gross intangible assets	$ 66		66
Accumulated amortization	$ (9)		(9)
PPA [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	14 years
Gross intangible assets	$ 198		0
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	15		15
Accumulated amortization	$ (8)		$ (7)
Other [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	10 years
Sempra Mexico [Member] | PPA [Member]
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	$ 198