CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (unaudited) - USD ($) shares in Millions, $ in Millions	Total		Common Stock [Member]	Additional Paid-in Capital [Member]	Unearned ESOP Compensation [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, 2014			443
Beginning Balance at Dec. 31, 2014	$ 20,168		$ 4	$ 7,193	$ (14)	$ (40)	$ 12,773	$ 19,916	$ 252
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,371						1,366	1,366	5
Issuances of common stock, net of issuance cost of less than $1 (in shares)			8
Issuances of common stock, net of issuance cost of less than $1			$ 1	626	2			629
Exercise of stock options and other incentive plan activity (in shares)			1
Exercise of stock options and other incentive plan activity				17				17
Dividends on common stock							(683)	(683)
Earned compensation under ESOP				20	3			23
Other comprehensive income (loss)	34					36		36	(2)
Sale of NEER assets to NEP				34				34	17
Distributions to noncontrolling interests									(7)
Other changes in noncontrolling interests in subsidiaries									(2)
Ending Balance (in shares) at Jun. 30, 2015			452
Ending Balance at Jun. 30, 2015	$ 21,601		$ 5	7,890	(9)	(4)	13,456	21,338	263
Beginning Balance (in shares) at Dec. 31, 2015	461		461
Beginning Balance at Dec. 31, 2015	$ 23,112		$ 5	8,597	(1)	(167)	14,140	22,574	538
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,198	[1]					1,193	1,193	5
Issuances of common stock, net of issuance cost of less than $1				16				16
Exercise of stock options and other incentive plan activity (in shares)			1
Exercise of stock options and other incentive plan activity				37				37
Dividends on common stock							(803)	(803)
Earned compensation under ESOP				26	1			27
Other comprehensive income (loss)	$ 72					85		85	(13)
Sale of NEER assets to NEP				27				27	199
Distributions to noncontrolling interests									(23)
Other changes in noncontrolling interests in subsidiaries									2
Adoption of accounting standards update							18	18
Ending Balance (in shares) at Jun. 30, 2016	462		462
Ending Balance at Jun. 30, 2016	$ 23,882		$ 5	$ 8,703	$ 0	$ (82)	$ 14,548	$ 23,174	$ 708

[1] Reflects the adoption in the second quarter of 2016 of an accounting standards update. See Note 6 - Stock-Based Compensation.