CONDENSED FINANCIAL INFORMATION OF PARENT - Statements of Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Statement of Income Captions [Line Items]
Net Income	$ 707	$ 581	$ 667
Comprehensive Income Attributable to Avangrid, Inc.	545	565	656
AVANGRID
Condensed Statement of Income Captions [Line Items]
Net Income	707	581	667
Other comprehensive loss of subsidiaries	(162)	(16)	(11)
Comprehensive Income Attributable to Avangrid, Inc.	$ 545	$ 565	$ 656