Investments (Unconsolidated Equity Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Carrying value	$ 585	$ 542	$ 508
Equity (income) / loss	(61)	(51)	(62)
ATC Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value	386	358
Equity (income) / loss	$ (49)	(41)	(43)
ATC LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	16.00%
ATC Holdco LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	20.00%
Non-utility wind farm in Oklahoma [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	50.00%
Carrying value	$ 104	101
Equity (income) / loss	(7)	(5)	(4)
Corporate venture investments [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value	74	62
Equity (income) / loss	(2)	(3)	(13)
Other [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value	21	21
Equity (income) / loss	(3)	(2)	(2)
Total [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value	585	542
Equity (income) / loss	$ (61)	$ (51)	$ (62)