Document and Entity Information (USD $)	6 Months Ended
	Jun. 30, 2011	Jul. 30, 2011	Jun. 30, 2010
Document And Entity Line Items
Entity Registrant Name	NORTHEAST UTILITIES
Document Period End Date	Jun. 30, 2011
Document Type	10-Q
Entity Central Index Key	0000072741
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		176,893,612
Entity Public Float			$ 4,486,982,187
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q2
Amendment Flag	false
The Connecticut Light and Power Company [Member]
Document And Entity Line Items
Entity Registrant Name	The Connecticut Light and Power Company
Entity Central Index Key	0000023426
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Public Service Company of New Hampshire [Member]
Document And Entity Line Items
Entity Registrant Name	Public Service Company of New Hampshire
Entity Central Index Key	0000315256
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Western Massachusetts Electric Company [Member]
Document And Entity Line Items
Entity Registrant Name	Western Massachusetts Electric Company
Entity Central Index Key	0000106170
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer