CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (unaudited) - 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, 2015			461
Beginning Balance at Dec. 31, 2015	$ 23,112		$ 5	$ 8,596	$ (167)	$ 14,140	[1]	$ 22,574	$ 538
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	654	[1]				653	[1]	653	1
Issuances of common stock, net of issuance cost of less than $1 (in shares)			0
Issuances of common stock, net of issuance cost of less than $1			$ 0	8				8
Share-based payment activity (in shares)			0
Share-based payment activity				14				14
Dividends on common stock						(401)	[1]	(401)
Other comprehensive income (loss)	40	[1]			54			54	(14)
Sale of NEER assets to NEP				27				27	198
Other changes in noncontrolling interests in subsidiaries				0		18	[1]	18	(5)
Ending Balance (in shares) at Mar. 31, 2016			461
Ending Balance at Mar. 31, 2016	$ 23,665		$ 5	8,645	(113)	14,410	[1]	22,947	718
Beginning Balance (in shares) at Dec. 31, 2016	468		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	1,591					1,583		1,583	8
Issuances of common stock, net of issuance cost of less than $1 (in shares)			0
Issuances of common stock, net of issuance cost of less than $1				6				6
Dividends on common stock						(460)		(460)
Other comprehensive income (loss)	$ 41				30			30	11
Other changes in noncontrolling interests in subsidiaries				(3)				(3)	(37)
Ending Balance (in shares) at Mar. 31, 2017	468		468
Ending Balance at Mar. 31, 2017	$ 26,469		$ 5	$ 8,951	$ (40)	$ 16,581		$ 25,497	$ 972

[1] Amounts have been retrospectively adjusted. See Note 7 - Stock-Based Compensation.