LONG-TERM DEBT (Details) (Public Service Company of New Hampshire [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2011
Public Service Company of New Hampshire [Member]
Debt Instrument Line Items
Proceeds From Issuance Of First Mortgage Bond	$ 122
Interest Rate On PSNH First Mortgage Bonds Issued In 2011	4.05%

The cash inflow from amounts received from debt instrument secured by a first mortgage deed of trust, containing a pledge of real property. The lender has the highest claim on the property in case of default.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 18

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 19
-Subparagraph b

Name:	us-gaap_ProceedsFromIssuanceOfFirstMortgageBond
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration