Variable Interest Entities (Textual) (Details) - Southern California Edison - Variable Interest Entity, Not Primary Beneficiary	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 31, 2017 USD ($)	Jun. 30, 2018 USD ($) $ / shares MW	Jun. 30, 2017 USD ($) MW	Jun. 30, 2018 USD ($) $ / shares MW	Jun. 30, 2017 USD ($) MW	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2012 USD ($)
SCE Power Purchase Contracts
Variable Interest Entity
Power generating capacity (in megawatts) | MW		3,575	4,900	3,575	4,900
Payments to unconsolidated VIEs for power purchase contracts		$ 99,000,000	$ 106,000,000	$ 239,000,000	$ 246,000,000
Trust II
Variable Interest Entity
Common stock		10,000		10,000		$ 10,000
Trust II | Trust Securities
Variable Interest Entity
Security dividend rate						5.10%
Liquidation preference		$ 400,000,000		$ 400,000,000		$ 400,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25		$ 25		$ 25
Common stock						$ 10,000
Trust II | Series F Preferred Stock
Variable Interest Entity
Liquidation value (in dollars per share) | $ / shares						$ 2,500
Trust II | Series G Preferred Stock
Variable Interest Entity
Security dividend rate				5.10%
Liquidation preference		$ 400,000,000		$ 400,000,000		$ 400,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500		$ 2,500
Trust III
Variable Interest Entity
Common stock		$ 10,000		$ 10,000		$ 10,000
Trust III | Trust Securities
Variable Interest Entity
Security dividend rate						5.75%
Liquidation preference		$ 275,000,000		$ 275,000,000		$ 275,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25		$ 25
Trust III | Series H Preferred Stock
Variable Interest Entity
Security dividend rate				5.75%
Liquidation preference		$ 275,000,000		$ 275,000,000		275,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500		$ 2,500
Trust IV
Variable Interest Entity
Common stock		$ 10,000		$ 10,000		$ 10,000
Trust IV | Trust Securities
Variable Interest Entity
Security dividend rate						5.375%
Liquidation preference		$ 325,000,000		$ 325,000,000		$ 325,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25		$ 25
Trust IV | Series J Preferred Stock
Variable Interest Entity
Security dividend rate				5.375%
Liquidation preference		$ 325,000,000		$ 325,000,000		325,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500		$ 2,500
Trust V
Variable Interest Entity
Common stock		$ 10,000		$ 10,000		$ 10,000
Trust V | Trust Securities
Variable Interest Entity
Security dividend rate						5.45%
Liquidation preference		$ 300,000,000		$ 300,000,000		$ 300,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25		$ 25
Trust V | Series K Preferred Stock
Variable Interest Entity
Security dividend rate				5.45%
Liquidation preference		$ 300,000,000		$ 300,000,000		300,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500		$ 2,500
Trust VI
Variable Interest Entity
Common stock		$ 10,000		$ 10,000		$ 10,000
Trust VI | Trust Securities
Variable Interest Entity
Security dividend rate						5.00%
Liquidation preference		$ 475,000,000		$ 475,000,000		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25		$ 25
Trust VI | Series L Preferred Stock
Variable Interest Entity
Security dividend rate				5.00%
Liquidation preference		$ 475,000,000		$ 475,000,000		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500		$ 2,500
Trust I | Trust Securities
Variable Interest Entity
Security dividend rate							5.625%
Liquidation preference	$ 475,000,000
Redemption of trust securities	$ 10,000						$ 10,000
Trust I | Series F Preferred Stock
Variable Interest Entity
Liquidation preference							$ 475,000,000