Compensation and Benefit Plans (Changes in Plan Assets and Benefits Obligations Recognized in OCI) (Details) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension and Other Postretirement Benefits [Line Items]
Net loss	$ 11	$ 19	$ 5
Amortization of net loss	(10)	(7)	(9)
Total recognized in other comprehensive loss	1	12	(4)
Total recognized in expense and other comprehensive loss	59	82	61
SCE
Pension and Other Postretirement Benefits [Line Items]
Net loss	9	21	5
Amortization of net loss	(7)	(5)	(6)
Total recognized in other comprehensive loss	2	16	(1)
Total recognized in expense and other comprehensive loss	$ 56	$ 80	$ 60