CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Millions, $ in Millions		Total		Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]		Retained Earnings [Member]	Total Common Shareholders' Equity Parent [Member]		Noncontrolling Interest [Member]
Beginning Balance (in shares) at Dec. 31, 2016				468
Beginning Balance at Dec. 31, 2016		$ 25,331		$ 5	$ 8,948	$ (70)		$ 15,458	$ 24,341		$ 990
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)		3,252	[1],[2]					3,223	3,223		29
Issuances of common stock, net of issuance cost of less than $1 (in shares)				2
Issuances of common stock, net of issuance cost of less than $1					24				24
Share-based payment activity					77				77
Dividends on common stock								(1,382)	(1,382)
Other comprehensive income		129				118			118		11
Sale of NEER assets to NEP											(17)
Other					(3)				(3)		(90)
Ending Balance (in shares) at Sep. 30, 2017				470
Ending Balance at Sep. 30, 2017		$ 27,321		$ 5	9,046	48		17,299	26,398		923
Beginning Balance (in shares) at Dec. 31, 2017		471		471
Beginning Balance at Dec. 31, 2017		$ 29,498		$ 5	9,100	111		18,992	28,208		1,290
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)		5,475						6,229	6,229		(754)
Issuances of common stock, net of issuance cost of less than $1 (in shares)				6
Issuances of common stock, net of issuance cost of less than $1					700				700
Share-based payment activity (in shares)				1
Share-based payment activity					82				82
Dividends on common stock								(1,570)	(1,570)
Other comprehensive income		1				1			1
Impact of NEP deconsolidation		$ (2,700)				58	[3]		58	[3]	(2,695)	[3]
Adoption of accounting standards updates	[4]				593	(328)		285	550		5,303
Other					(5)			(1)	(6)		(58)
Ending Balance (in shares) at Sep. 30, 2018		478		478
Ending Balance at Sep. 30, 2018		$ 37,338		$ 5	$ 10,470	$ (158)		$ 23,935	$ 34,252		$ 3,086

[1] Prior period amounts have been retrospectively adjusted as discussed in Note 11 - Restricted Cash.

[2] Prior period amounts have been retrospectively adjusted as discussed in Note 3 - Amendments to Presentation of Retirement Benefits.

[3] See Note 2.

[4] See Notes 1, 5 - Financial Instruments Accounting Standards Update, 6 and 11 - Accounting for Partial Sales of Nonfinancial Assets.