Audit Information	12 Months Ended
	Dec. 31, 2021
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut
The Connecticut Light and Power Company
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut
NSTAR Electric Company
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut
Public Service Company of New Hampshire
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut