Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Data [Line Items]
Total operating revenue	$ 3,157	$ 4,644	$ 2,987	$ 2,790	$ 2,970	$ 3,741	$ 2,812	$ 2,824	$ 13,578	$ 12,347	$ 12,657
Operating income (loss)	794	(379)	500	302	287	636	500	352	1,217	1,775	(552)
Net income (loss)	552	(242)	348	213	173	502	422	308	$ 871	$ 1,405	$ (316)
Net income attributable to common shareholders	$ 526	$ (288)	$ 318	$ 183	$ 143	$ 471	$ 392	$ 278
Basic earnings (loss) per share (in dollars per share)	$ 1.39	$ (0.76)	$ 0.85	$ 0.50	$ 0.40	$ 1.36	$ 1.20	$ 0.85	$ 1.98	$ 3.78	$ (1.30)
Diluted earnings (loss) per share (in dollars per share)	1.39	(0.76)	0.85	0.50	0.40	1.35	1.20	0.85	1.98	3.77	(1.30)
Dividends declared per common share (in dollars per share)	$ 0.6625	$ 0.6375	$ 0.6375	$ 0.6375	$ 0.6375	$ 0.6125	$ 0.6125	$ 0.6125	$ 2.5750	$ 2.4750	$ 2.4275
SCE
Quarterly Financial Data [Line Items]
Total operating revenue	$ 3,151	$ 4,635	$ 2,980	$ 2,780	$ 2,958	$ 3,732	$ 2,800	$ 2,816	$ 13,546	$ 12,306	$ 12,611
Operating income (loss)	678	(364)	548	316	325	649	513	358	1,178	1,845	(406)
Net income (loss)	500	(218)	411	249	224	534	449	323	942	1,530	(189)
Net income attributable to common shareholders	474	(264)	381	219	194	503	419	293	$ 810	$ 1,409	$ (310)
Dividends declared per common share (in dollars per share)									$ 2.6030	$ 1.3797	$ 1.3245
Common dividends declared	$ 325	$ 269	$ 269	$ 269	$ 200	$ 200	$ 0	$ 200