Background and Nature of Operations (Details) $ / shares in Units, $ in Millions	May 18, 2021 USD ($) placement $ / shares shares	Apr. 15, 2021	Oct. 20, 2020 USD ($) $ / shares	Dec. 31, 2022 $ / shares	Dec. 31, 2021 $ / shares	Dec. 31, 2020 $ / shares
Noncontrolling Interest [Line Items]
Sale of stock, number of shares issued (in shares) | shares	77,821,012
Sale of stock, number of placements | placement	2
Common stock, par value (in dollars per share) | $ / shares	$ 0.01			$ 0.01	$ 0.01	$ 0.01
Sale of stock, price (in dollars per share) | $ / shares	$ 51.40
Proceeds of private placements	$ 4,000
Proceeds of private placements used to repay debt	3,000
NM Green Holdings, Inc.
Noncontrolling Interest [Line Items]
Merger agreement, share price (in dollars per share) | $ / shares			$ 50.30
Merger agreement term, ownership percentage benchmark			15.00%
Merger agreement, termination rights term, extension period			3 months
Merger agreement, termination rights term, termination fees			$ 130
Merger agreement, termination rights term, termination fees as remedy			184
Merger agreement, termination rights term, termination fees, out-of-pocket fees and expenses reimbursable limit (up to)			$ 10
NM Green Holdings, Inc. | Side Letter Agreement Associated With Merger
Noncontrolling Interest [Line Items]
Debt basis spread on variable rate		0.75%
Facility fee percentage on undrawn portion of funding commitment		0.12%
Merger With PNMR
Noncontrolling Interest [Line Items]
Acquisition, commitment letter amount	$ 4,300
Hyde Member LLC and Subsidiary of Qatar Investment Authority
Noncontrolling Interest [Line Items]
Sale of stock, number of shares issued (in shares) | shares	14,396,887
Iberdrola S.A.
Noncontrolling Interest [Line Items]
Sale of stock, number of shares issued (in shares) | shares	63,424,125
Avangrid | Iberdrola S.A.
Noncontrolling Interest [Line Items]
Parent company, ownership percentage				81.60%
Avangrid | Various Shareholders
Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners				18.40%