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, 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		1,591	[1],[2]					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				$ 0	6					6
Dividends on common stock								(460)		(460)
Other comprehensive income (loss)		41				30				30		11
Other					(3)			0		(3)		(37)
Ending Balance (in shares) at Mar. 31, 2017				468
Ending Balance at Mar. 31, 2017		$ 26,469		$ 5	8,951	(40)		16,581		25,497		972
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		3,831						4,428		4,428		(597)
Share-based payment activity (in shares)				0
Share-based payment activity					5					5
Dividends on common stock								(523)		(523)
Other comprehensive income (loss)		(19)				(19)				(19)		0
NEP deconsolidation		$ (2,700)				58	[3]	0	[3]	58	[3]	(2,695)	[3]
Adoption of accounting standards updates(b)	[4]				593	(328)		285		550		5,303
Other					0	0		(1)		(1)		(14)
Ending Balance (in shares) at Mar. 31, 2018		471		471
Ending Balance at Mar. 31, 2018		$ 35,993		$ 5	$ 9,698	$ (178)		$ 23,181		$ 32,706		$ 3,287

[1] Prior period amounts have been retrospectively adjusted as discussed in Note 10 - 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 10 - Accounting for Partial Sales of Nonfinancial Assets.