Variable Interest Entities (Variable Interest in VIEs that are not Consolidated) (Details)	1 Months Ended	12 Months Ended
	Jul. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) $ / shares MW	Dec. 31, 2016 USD ($) $ / shares MW	Dec. 31, 2015 USD ($)
Unconsolidated Trust
Stock redeemed		$ 475,000,000	$ 125,000,000	$ 325,000,000
SCE
Unconsolidated Trust
Stock redeemed		$ 475,000,000	$ 125,000,000	$ 325,000,000
SCE | Series F Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.625%
SCE | Series G Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.10%
SCE | Series H Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.75%
SCE | Series J Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.375%
SCE | Series K Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.45%
SCE | Series L Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.00%
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Power Purchase Contracts
Details of projects or entities
Power generating capacity for majority interest (in megawatts) | MW		4,898	4,353
Payments to unconsolidated VIEs for power purchase contracts		$ 767,000,000	$ 788,000,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust I
Unconsolidated Trust
Common stock		$ 10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust I | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.625%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25
Common stock		$ 10,000
Stock redeemed	$ 10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust I | Series F Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.625%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust II
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust II | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.10%
Liquidation preference		$ 400,000,000	$ 400,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust II | Series G Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.10%
Liquidation preference		$ 400,000,000	$ 400,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust III
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust III | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.75%
Liquidation preference		$ 275,000,000	$ 275,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust III | Series H Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.75%
Liquidation preference		$ 275,000,000	$ 275,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust IV
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust IV | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.375%
Liquidation preference		$ 325,000,000	$ 325,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust IV | Series J Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.375%
Liquidation preference		$ 325,000,000	$ 325,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust V
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust V | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.45%
Liquidation preference		$ 300,000,000	$ 300,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust V | Series K Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.45%
Liquidation preference		$ 300,000,000	$ 300,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust VI
Unconsolidated Trust
Common stock		$ 10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust VI | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.00%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25
Stock redeemed	$ 475,000,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust VI | Series L Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.00%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500