CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities:
Net Income	$ 702,319	$ 603,576
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	495,389	456,224
Deferred Income Tax Expense (Benefit)	153,353	64,755
Pension, SERP and PBOP Expense	71,802	74,296
Pension and PBOP Contributions	(162,880)	(74,681)
Regulatory Over/(Under) Recoveries, Net	31,874	290,111
Amortization of Regulatory Assets/(Liabilities), Net	42,587	31,826
Proceeds from DOE Damages Claim, Net	0	132,138
Other	(49,548)	(17,096)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(148,442)	(66,463)
Increase Decrease in Fuel, Materials and Supplies	47,380	(27,147)
Taxes Receivable/(Accrued)	383,047	26,533
Accounts Payable	(233,660)	(69,448)
Other Current Assets and Liabilities, Net	8,370	(20,607)
Net Cash Flows Provided by Operating Activities	1,341,591	1,404,017
Investing Activities:
Investments in Property, Plant and Equipment	(1,177,285)	(1,117,493)
Proceeds from Sales of Marketable Securities	556,582	388,352
Purchases of Marketable Securities	(535,044)	(389,406)
Other Investing Activities	(2,769)	(4,669)
Net Cash Flows Used in Investing Activities	(1,158,516)	(1,123,216)
Financing Activities:
Cash Dividends on Common Stock	(397,363)	(356,080)
Cash Dividends on Preferred Stock	(5,639)	(5,639)
Increase/(Decrease) in Short-Term Debt	(387,575)	6,000
Issuance of Long-Term Debt	825,000	650,000
Retirements of Long-Term Debt	(216,700)	(576,650)
Other Financing Activities	(3,720)	(90)
Net Cash Flows Provided by/(Used in) Financing Activities	(185,997)	(282,459)
Net Increase/(Decrease) in Cash	(2,922)	(1,658)
Cash - Beginning of Year	38,703	43,364
Cash - End of Year	35,781	41,706
The Connecticut Light And Power Company [Member]
Operating Activities:
Net Income	228,192	200,560
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	159,903	139,598
Deferred Income Tax Expense (Benefit)	(11,011)	(14,400)
Pension, SERP and PBOP Expense, Net of Contributions	10,654	8,050
Regulatory Over/(Under) Recoveries, Net	12,504	62,929
Amortization of Regulatory Assets/(Liabilities), Net	17,917	62,644
Proceeds from DOE Damages Claim		68,610
Other	(13,048)	(11,290)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(91,842)	(87,922)
Taxes Receivable/(Accrued)	160,031	39,805
Accounts Payable	(20,485)	16,984
Other Current Assets and Liabilities, Net	(31,044)	(2,575)
Net Cash Flows Provided by Operating Activities	421,771	482,993
Investing Activities:
Investments in Property, Plant and Equipment	(359,339)	(371,660)
Other Investing Activities	(740)	(4,539)
Net Cash Flows Used in Investing Activities	(360,079)	(376,199)
Financing Activities:
Cash Dividends on Common Stock	(147,000)	(128,400)
Cash Dividends on Preferred Stock	(4,169)	(4,169)
Issuance of Long-Term Debt	300,000	250,000
Increase/(Decrease) in Notes Payable to Affiliate	(133,400)	(181,900)
Retirements of Long-Term Debt	(162,000)	(150,000)
Capital Contributions from NU Parent	105,000	120,000
Other Financing Activities	(9,072)	(3,268)
Net Cash Flows Provided by/(Used in) Financing Activities	(50,641)	(97,737)
Net Increase/(Decrease) in Cash	11,051	9,057
Cash - Beginning of Year	2,356	7,237
Cash - End of Year	13,407	16,294
NSTAR Electric Company [Member]
Operating Activities:
Net Income	284,148	233,791
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	146,818	140,996
Deferred Income Tax Expense (Benefit)	54,188	(39,399)
Pension, SERP and PBOP Expense, Net of Contributions	(1,138)	(11,046)
Regulatory Over/(Under) Recoveries, Net	(48,903)	155,357
Amortization of Regulatory Assets/(Liabilities), Net	(10,643)	(916)
Proceeds from DOE Damages Claim		30,193
Other	(34,223)	(41,601)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(107,711)	(47,770)
Increase Decrease in Fuel, Materials and Supplies	21,863	(20,837)
Taxes Receivable/(Accrued)	207,516	60,252
Accounts Payable	(41,447)	(40,594)
Accounts Payable Related Parties	(14,878)	66,758
Other Current Assets and Liabilities, Net	46,671	32,340
Net Cash Flows Provided by Operating Activities	502,261	517,524
Investing Activities:
Investments in Property, Plant and Equipment	(314,055)	(309,248)
Net Cash Flows Used in Investing Activities	(314,055)	(309,248)
Financing Activities:
Cash Dividends on Common Stock	(148,500)	(253,000)
Cash Dividends on Preferred Stock	(1,470)	(1,470)
Increase/(Decrease) in Short-Term Debt	(43,500)	56,000
Issuance of Long-Term Debt	0	300,000
Retirements of Long-Term Debt	(4,700)	(301,650)
Other Financing Activities	0	(5,137)
Net Cash Flows Provided by/(Used in) Financing Activities	(198,170)	(205,257)
Net Increase/(Decrease) in Cash	(9,964)	3,019
Cash - Beginning of Year	12,773	8,021
Cash - End of Year	2,809	11,040
Public Service Company Of New Hampshire [Member]
Operating Activities:
Net Income	92,491	84,955
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	77,989	73,247
Deferred Income Tax Expense (Benefit)	42,563	67,827
Regulatory Over/(Under) Recoveries, Net	2,639	16,813
Amortization of Regulatory Assets/(Liabilities), Net	29,148	(17,565)
Proceeds from DOE Damages Claim		14,453
Other	10,894	10,834
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(25,126)	(7,467)
Increase Decrease in Fuel, Materials and Supplies	4,156	(17,350)
Taxes Receivable/(Accrued)	9,026	(24,108)
Accounts Payable	(20,058)	(9,297)
Other Current Assets and Liabilities, Net	20,141	13,470
Net Cash Flows Provided by Operating Activities	243,863	205,812
Investing Activities:
Investments in Property, Plant and Equipment	(209,522)	(170,127)
Other Investing Activities	241	(148)
Net Cash Flows Used in Investing Activities	(209,281)	(170,275)
Financing Activities:
Cash Dividends on Common Stock	(79,500)	(49,500)
Increase/(Decrease) in Notes Payable to Affiliate	46,800	66,800
Retirements of Long-Term Debt		(50,000)
Other Financing Activities	(268)	(217)
Net Cash Flows Provided by/(Used in) Financing Activities	(32,968)	(32,917)
Net Increase/(Decrease) in Cash	1,614	2,620
Cash - Beginning of Year	489	130
Cash - End of Year	2,103	2,750
Western Massachusetts Electric Company [Member]
Operating Activities:
Net Income	42,410	39,785
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	32,420	31,144
Deferred Income Tax Expense (Benefit)	5,531	13,479
Regulatory Over/(Under) Recoveries, Net	4,024	33,630
Amortization of Regulatory Assets/(Liabilities), Net	11,194	(7,778)
Proceeds from DOE Damages Claim		18,883
Other	(4,500)	615
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(32,664)	36,075
Taxes Receivable/(Accrued)	24,064	(15,831)
Accounts Payable	(14,018)	(12,847)
Other Current Assets and Liabilities, Net	(463)	(16,551)
Net Cash Flows Provided by Operating Activities	67,998	120,604
Investing Activities:
Investments in Property, Plant and Equipment	(93,705)	(82,546)
Proceeds from Sales of Marketable Securities	71,110	58,788
Purchases of Marketable Securities	(71,625)	(59,280)
Net Cash Flows Used in Investing Activities	(94,220)	(83,038)
Financing Activities:
Cash Dividends on Common Stock	(27,900)	(49,000)
Increase/(Decrease) in Notes Payable to Affiliate	104,800	13,200
Retirements of Long-Term Debt	50,000
Other Financing Activities	(20)	(29)
Net Cash Flows Provided by/(Used in) Financing Activities	26,880	(35,829)
Net Increase/(Decrease) in Cash	658	1,737
Cash - Beginning of Year	0	0
Cash - End of Year	$ 658	$ 1,737