Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Millions		Total	Common Stock		Additional paid-in capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Total Stockholders' Equity	Non controlling Interests
Balance at Dec. 31, 2015		$ 15,066	$ 3		$ 13,653		$ 1,449	$ (52)	$ 15,053	$ 13
Balance, shares at Dec. 31, 2015	[1]		308,864,609
Net Income		212					212		212
Other comprehensive income (loss), net of tax		(20)						(20)	(20)
Comprehensive Income Attributable to Avangrid, Inc.		192
Dividends declared		$ (134)					(134)		(134)
Release of common stock held in trust		132,800	132,800	[1]
Issuance of common stock, shares		97,479	97,479	[1]
Balance at Mar. 31, 2016		$ 15,124	$ 3		13,653		1,527	(72)	15,111	13
Balance, shares at Mar. 31, 2016	[1]		309,094,888
Balance at Dec. 31, 2016		$ 15,122	$ 3		13,653	$ (5)	1,544	(86)	15,109	13
Balance, shares at Dec. 31, 2016		308,993,149	308,993,149	[1]
Net Income		$ 239					239		239
Other comprehensive income (loss), net of tax		25						25	25
Comprehensive Income Attributable to Avangrid, Inc.		264
Dividends declared		$ (134)					(134)		(134)
Release of common stock held in trust		5,649	5,649	[1]
Issuance of common stock		$ (1)			(1)				(1)
Issuance of common stock, shares		70,493	70,493	[1]
Stock-based compensation		$ 1			1				1
Balance at Mar. 31, 2017		$ 15,252	$ 3		$ 13,653	$ (5)	$ 1,649	$ (61)	$ 15,239	$ 13
Balance, shares at Mar. 31, 2017		309,069,291	309,069,291	[1]

[1] Par value of share amounts is $0.01