Condensed Consolidated Statements of Income (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Operating Revenues	$ 1,789	$ 1,842
Operating Expenses
Purchased power, natural gas and fuel used	475	563
Operations and maintenance	570	553
Depreciation and amortization	251	222
Taxes other than income taxes	166	163
Total Operating Expenses	1,462	1,501
Operating Income	327	341
Other Income and (Expense)
Other expense	(3)	(7)
(Losses) earnings from equity method investments	(6)	1
Interest expense, net of capitalization	(76)	(78)
Income Before Income Tax	242	257
Income tax expense	12	41
Net Income	230	216
Net loss attributable to noncontrolling interests	10	1
Net Income Attributable to Avangrid, Inc.	$ 240	$ 217
Earnings Per Common Share, Basic (in usd per share)	$ 0.78	$ 0.70
Earnings Per Common Share, Diluted (in usd per share)	$ 0.78	$ 0.70
Weighted-average Number of Common Shares Outstanding:
Basic (in shares)	309,491,082	309,491,082
Diluted (in shares)	309,623,573	309,712,308