LONG-TERN DEBT - Long-Term Debt Provisions (Details)	12 Months Ended
Dec. 31, 2016
Public Service Company Of New Hampshire [Member] \| Senior Notes [Member] \| Adjustable Rate Tax Exempt Series A Notes Due 2021 [Member]
Debt Instrument [Line Items]
Par value of stock (as a percentage)	100.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Balance Type:	na
Period Type:	duration