Summary of Significant Accounting Policies (Regulatory Proceedings) (Details) - Southern California Edison - USD ($) $ in Millions		1 Months Ended	3 Months Ended		12 Months Ended	15 Months Ended
	Aug. 31, 2020	Sep. 30, 2020	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
CPUC | 2018 GRC
Public Utilities, General Disclosures [Line Items]
Impact of decision non-core impairment of utility core earnings, net of tax				$ 66	$ 65	$ 131
Reduction in revenue						$ 265
Reduction in authorized revenue					$ 289
Increase in approved revenue				$ 24
Impact of decision non-core impairment of utility property, plant and equipment			$ 170
Impact of decision non-core impairment of utility property, plant and equipment, net of tax			$ 123
FERC | 2019 Formula Rate Settlement
Public Utilities, General Disclosures [Line Items]
Approved ROE		10.30%
Alternative ROE		47.50%
Settlement period base ROE	11.97%