CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating Activities:
Net Income	$ 614,413	$ 356,482
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	463,635	369,798
Deferred Income Tax Expense (Benefit)	334,225	186,181
Pension and PBOP Expense, Net of PBOP Contributions	146,803	160,209
Pension and Other Postretirement Benefit Contributions	(338,301)	(237,123)
Regulatory (Underrecoveries)/Overrecoveries, Net	66,239	(26,236)
Amortization of Regulatory Assets/(Liabilities), Net	178,668	74,851
Amortization of Rate Reduction Bonds	42,581	102,144
Other Noncash Income (Expense)	3,158	6,640
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(98,432)	(27,677)
Inventory	(13,134)	32,887
Taxes Receivable/(Accrued)	(28,609)	26,302
Change in Accounts Payable	(112,512)	(208,308)
Other Current Assets and Liabilities	(81,766)	(20,145)
Net Cash Flows Provided by Operating Activities	1,176,968	796,005
Investing Activities:
Investments in Property, Plant and Equipment	(1,073,759)	(1,081,750)
Proceeds from Sales of Marketable Securities	487,729	232,911
Purchases of Marketable Securities	(541,070)	(252,762)
DecreaseInRestrictedCash	69,259	6,199
Other Investing Activities	(1,137)	34,066
Net Cash Flows Used in Investing Activities	(1,058,978)	(1,061,336)
Financing Activities:
Cash Dividends on Common Stock	(341,720)	(267,356)
Cash Dividends on Preferred Stock	(5,802)	(5,149)
Increase/(Decrease) in Short-Term Debt	(172,000)	654,250
Issuance of Long-Term Debt	1,350,000	300,000
Retirements of Long-Term Debt	(840,600)	(267,561)
Retirements of Rate Reduction Bonds	(82,139)	(95,225)
Other Financing Activities	(13,536)	13,262
Net Cash Flows Provided by/(Used in) Financing Activities	(105,797)	332,221
Net Increase/(Decrease) in Cash	12,193	66,890
Cash - Beginning of Year	45,748	6,559
Cash - End of Year	57,941	73,449
The Connecticut Light And Power Company [Member]
Operating Activities:
Net Income	219,188	135,804
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	132,356	124,451
Deferred Income Tax Expense (Benefit)	89,084	97,224
Pension and PBOP Expense, Net of PBOP Contributions	16,182	18,394
Regulatory (Underrecoveries)/Overrecoveries, Net	24,061	(13,804)
Amortization of Regulatory Assets/(Liabilities), Net	11,223	19,912
Other Noncash Income (Expense)	(8,759)	(10,701)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(44,523)	(21,632)
Taxes Receivable/(Accrued)	841	21,410
Change in Accounts Payable	(101,949)	(173,107)
Other Current Assets and Liabilities	(29,106)	(49,750)
Net Cash Flows Provided by Operating Activities	308,598	148,201
Investing Activities:
Investments in Property, Plant and Equipment	(294,638)	(332,323)
Other Investing Activities	2,013	13,707
Net Cash Flows Used in Investing Activities	(292,625)	(318,616)
Financing Activities:
Cash Dividends on Common Stock	(114,000)	(100,486)
Cash Dividends on Preferred Stock	(4,169)	(4,169)
Increase/(Decrease) in Short-Term Debt	(89,000)	(31,000)
Issuance of Long-Term Debt	400,000
Increase/(Decrease) in Notes Payable to Affiliate	(62,200)	314,275
Retirements of Long-Term Debt	(125,000)
Other Financing Activities	(6,352)	(1,636)
Net Cash Flows Provided by/(Used in) Financing Activities	(721)	176,984
Net Increase/(Decrease) in Cash	15,252	6,569
Cash - Beginning of Year	1	1
Cash - End of Year	15,253	6,570
NSTAR Electric Company [Member]
Operating Activities:
Net Income	213,162	156,184
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	19,012	53,254
Depreciation	136,323	127,692
Deferred Income Tax Expense (Benefit)	26,358	(20,250)
Pension and PBOP Expense, Net of PBOP Contributions	(55,195)	1,394
Regulatory (Underrecoveries)/Overrecoveries, Net	(11,299)	62,075
Amortization of Regulatory Assets/(Liabilities), Net	173,289	87,912
Amortization of Rate Reduction Bonds	15,054	67,742
Other Noncash Income (Expense)	(48,291)	(29,154)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(80,575)	(61,528)
Inventory	7,961	7,264
Taxes Receivable/(Accrued)	(6,345)	44,142
Change in Accounts Payable	6,856	(81,292)
Other Current Assets and Liabilities	(19,547)	58,890
IncreaseDecreaseInAccountsPayableRelatedParties	(59,173)	(41,760)
Net Cash Flows Provided by Operating Activities	317,590	432,565
Investing Activities:
Investments in Property, Plant and Equipment	(330,635)	(298,424)
DecreaseInRestrictedCash	37,899	25,234
Other Investing Activities	575	375
Net Cash Flows Used in Investing Activities	(292,161)	(272,815)
Financing Activities:
Cash Dividends on Common Stock	(56,000)	(188,700)
Cash Dividends on Preferred Stock	(1,633)	(1,470)
Increase/(Decrease) in Short-Term Debt	(120,000)	104,500
Issuance of Long-Term Debt	200,000	0
Retirements of Long-Term Debt	(1,650)	(688)
Retirements of Rate Reduction Bonds	(43,493)	(84,367)
Other Financing Activities	(878)	13,336
Net Cash Flows Provided by/(Used in) Financing Activities	(23,654)	(157,389)
Net Increase/(Decrease) in Cash	1,775	2,361
Cash - Beginning of Year	13,695	9,373
Cash - End of Year	15,470	11,734
Public Service Company Of New Hampshire [Member]
Operating Activities:
Net Income	84,543	69,726
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	68,433	65,282
Deferred Income Tax Expense (Benefit)	57,066	39,108
Pension and PBOP Expense, Net of PBOP Contributions	20,427	19,508
Pension and Other Postretirement Benefit Contributions	(112,964)	(94,169)
Regulatory (Underrecoveries)/Overrecoveries, Net	(1,346)	1,718
Amortization of Regulatory Assets/(Liabilities), Net	(1,745)	(6,179)
Amortization of Rate Reduction Bonds	19,748	43,855
Other Noncash Income (Expense)	7,165	18,699
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	8,047	(4,274)
Inventory	(30,456)	20,178
Taxes Receivable/(Accrued)	5,103	4,506
Change in Accounts Payable	29,148	(18,567)
Other Current Assets and Liabilities	7,220	18,358
Net Cash Flows Provided by Operating Activities	160,389	177,749
Investing Activities:
Investments in Property, Plant and Equipment	(155,676)	(161,021)
(Increase) Decrease In Notes Receivable From Affiliated Company	0	55,900
DecreaseInRestrictedCash	22,039	2,599
Other Investing Activities	(53)	(99)
Net Cash Flows Used in Investing Activities	(133,690)	(102,621)
Financing Activities:
Cash Dividends on Common Stock	(51,000)	(74,675)
Increase/(Decrease) in Short-Term Debt	165,200	44,200
Retirements of Long-Term Debt	(108,950)	0
Retirements of Rate Reduction Bonds	(29,294)	(41,265)
Other Financing Activities	456	(349)
Net Cash Flows Provided by/(Used in) Financing Activities	(23,588)	(72,089)
Net Increase/(Decrease) in Cash	3,111	3,039
Cash - Beginning of Year	2,493	56
Cash - End of Year	5,604	3,095
Western Massachusetts Electric Company [Member]
Operating Activities:
Net Income	50,041	39,408
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	27,707	22,154
Deferred Income Tax Expense (Benefit)	79,401	30,565
Regulatory (Underrecoveries)/Overrecoveries, Net	11,685	(8,733)
Amortization of Regulatory Assets/(Liabilities), Net	(598)	634
Amortization of Rate Reduction Bonds	7,780	13,127
Other Noncash Income (Expense)	(544)	1,755
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(32,231)	(10,482)
Taxes Receivable/(Accrued)	16,412	7,337
Change in Accounts Payable	20,260	(28,510)
Other Current Assets and Liabilities	(9,857)	(9,185)
Net Cash Flows Provided by Operating Activities	170,056	58,070
Investing Activities:
Investments in Property, Plant and Equipment	(127,352)	(218,184)
Proceeds from Sales of Marketable Securities	53,552	65,131
Purchases of Marketable Securities	(54,042)	(65,664)
(Increase) Decrease In Notes Receivable From Affiliated Company		11,000
Other Investing Activities	7,401	308
Net Cash Flows Used in Investing Activities	(120,441)	(207,409)
Financing Activities:
Cash Dividends on Common Stock	(30,000)	(9,431)
Increase/(Decrease) in Notes Payable to Affiliate	47,900	172,500
Retirements of Long-Term Debt	(55,000)
Retirements of Rate Reduction Bonds	(9,352)	(13,141)
Other Financing Activities	(7)	(54)
Net Cash Flows Provided by/(Used in) Financing Activities	(46,459)	149,874
Net Increase/(Decrease) in Cash	3,156	535
Cash - Beginning of Year	1	1
Cash - End of Year	$ 3,157	$ 536