Acquisitions, Development and Divestitures - Development (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Business Acquisition [Line Items]
Goodwill, Acquired During Period						$ 1,585
Transition Service Agreement Cost	$ 59				$ 179
Goodwill	2,247				2,247		$ 2,248
Operating Revenues from external customers	2,043	$ 2,134			6,281	5,612
Net income (loss)	230	174			627	566
Indemnification for Safari sale/leaseback					25
Narragansett Electric
Business Acquisition [Line Items]
Total cash consideration				$ 3,800
Disposal Group, Held-for-Sale, Not Discontinued Operations [Member] | Safari Holdings LLC, Consolidated
Business Acquisition [Line Items]
Gain (Loss) on Disposition of Business		(67)			(6)	(67)
gain (loss) on disposition of business, net of tax		(50)			(5)	(50)
Rhode Island Regulated
Business Acquisition [Line Items]
Goodwill			$ 725
Operating Revenues from external customers	413	384			1,355	512
Net income (loss)	6	(26)			70	(55)
Corporate and Other [Member]
Business Acquisition [Line Items]
Goodwill, Acquired During Period			860
Goodwill, Purchase Accounting Adjustments			$ 1
Operating Revenues from external customers	0	7			0	19
Net income (loss)	(87)	$ (107)			(259)	$ (254)
Rhode Island Energy | Rhode Island Energy TSA
Business Acquisition [Line Items]
Other Nonrecurring (Income) Expense	69				193
Rhode Island Energy | Accrual for TSA Markup
Business Acquisition [Line Items]
Other Nonrecurring (Income) Expense	$ 2				$ 6