Equity (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	May 31, 2019
Class of Stock [Line Items]
Shares issued (in shares)	14,181,882
Proceeds received	$ 800.0
Offering expenses	$ 14.0
Shares issued		$ 815.0	$ 88.0
ATM
Class of Stock [Line Items]
Shares issued (in shares)		0		391,501
Proceeds received				$ 27.0
Offering expenses				0.3
Aggregate sales price (up to)					$ 1,500.0
Aggregate sales price remaining		$ 1,300.0		1,300.0
401(k) defined contribution savings plan
Class of Stock [Line Items]
Proceeds received		$ 26.0		$ 72.0
Issuance of new common stock (in shares)		448,000		1,171,800
Stock compensation awards
Class of Stock [Line Items]
Proceeds received		$ 1.0		$ 14.0
Issuance of new common stock (in shares)		20,571		333,693
In lieu of dividend payment
Class of Stock [Line Items]
Proceeds received		$ 5.0		$ 9.0
Issuance of new common stock (in shares)		72,910		129,019
Southern California Edison
Class of Stock [Line Items]
Capital contributions		$ 619.0		$ 888.0