Fair Value Measurements (Level 3 Rollforward) (Details) - SCE - Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value Disclosures Level 3 [Roll Forward]
Fair value of net liabilities at beginning of period	$ (1,148)	$ (902)
Total realized/unrealized gains (losses):
Included in regulatory assets and liabilities	59	(246)
Fair value of net liabilities at end of period	(1,089)	(1,148)
Change during the period in unrealized gains and losses related to assets and liabilities held at the end of the period	$ (70)	$ (311)