CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - 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, 2013		435
Beginning Balance at Dec. 31, 2013	$ 18,040	$ 4	$ 6,437	$ (26)	$ 56	$ 11,569	$ 18,040	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,585					1,581	1,581	4
Issuances of common stock, net of issuance cost of less than $1			39	3			42
Exercise of stock options and other incentive plan activity (in shares)		1
Exercise of stock options and other incentive plan activity			66				66
Dividends on common stock						(945)	(945)
Earned compensation under ESOP			31	5			36
Other comprehensive loss	(9)				(9)		(9)
NEP acquisition of limited partnership interest in NEP OpCo								232
Other						1	1	(98)
Ending Balance (in shares) at Sep. 30, 2014		436
Ending Balance at Sep. 30, 2014	$ 19,144	$ 4	6,573	(18)	47	12,204	18,810	334
Beginning Balance (in shares) at Dec. 31, 2014	443	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	2,252					2,245	2,245	7
Issuances of common stock, net of issuance cost of less than $1 (in shares)		17
Issuances of common stock, net of issuance cost of less than $1		$ 1	1,289	3			1,293
Exercise of stock options and other incentive plan activity (in shares)		1
Exercise of stock options and other incentive plan activity			58				58
Dividends on common stock						(1,031)	(1,031)
Earned compensation under ESOP			31	5			36
Premium on equity units			(80)				(80)
Other comprehensive loss	$ (134)				(128)		(128)	(6)
Issuance costs of equity units			(25)				(25)
Sale of NEER assets to NEP			34				34	261
Distributions to noncontrolling interests								(13)
Other								7
Ending Balance (in shares) at Sep. 30, 2015	461	461
Ending Balance at Sep. 30, 2015	$ 22,826	$ 5	$ 8,500	$ (6)	$ (168)	$ 13,987	$ 22,318	$ 508