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	$ 22,574	$ 538
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,988				1,946	1,946	42
Issuances of common stock, net of issuance cost of less than $1 (in shares)		5
Issuances of common stock, net of issuance cost of less than $1		$ 0	523			523
Share-based payment activity (in shares)		1
Share-based payment activity			96			96
Dividends on common stock					(1,205)	(1,205)
Premium on equity units			(200)			(200)
Other comprehensive income (loss)	112			131		131	(19)
Sale of NEER assets to NEP			49			49	440
Distributions to noncontrolling interests							(37)
Other			(25)		18	(7)	(2)
Ending Balance (in shares) at Sep. 30, 2016		467
Ending Balance at Sep. 30, 2016	$ 24,869	$ 5	9,039	(36)	14,899	23,907	962
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	3,252				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 (in shares)		0
Share-based payment activity			77			77
Dividends on common stock					(1,382)	(1,382)
Other comprehensive income (loss)	$ 129			118		118	11
Sale of NEER assets to NEP			0			0	(17)
Distributions to noncontrolling interests							(64)
Other			(3)			(3)	(26)
Ending Balance (in shares) at Sep. 30, 2017	470	470
Ending Balance at Sep. 30, 2017	$ 27,321	$ 5	$ 9,046	$ 48	$ 17,299	$ 26,398	$ 923