CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating Activities:
Net Income	$ 403,032	$ 146,974
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	314,530	225,324
Deferred Income Tax Expense (Benefit)	256,294	59,509
Pension and PBOP Expense, Net of PBOP Contributions	97,671	97,378
Pension and Other Postretirement Benefit Contributions	(122,826)	(164,294)
Regulatory (Underrecoveries)/Overrecoveries, Net	(4,793)	(54,491)
Amortization of Regulatory Assets/(Liabilities), Net	108,623	31,016
Amortization of Rate Reduction Bonds	42,581	59,100
Other Noncash Income (Expense)	19,932	19,520
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(101,229)	83,395
Inventory	10,964	40,695
Taxes Receivable/(Accrued)	(58,350)	17,709
Change in Accounts Payable	(127,379)	(176,533)
Other Current Assets and Liabilities	(70,026)	(64,899)
Net Cash Flows Provided by Operating Activities	769,024	320,403
Investing Activities:
Investments in Property, Plant and Equipment	(700,252)	(690,376)
Proceeds from Sales of Marketable Securities	342,251	132,580
Purchases of Marketable Securities	(424,096)	(143,225)
DecreaseInRestrictedCash	65,121	(11,852)
Other Investing Activities	(843)	23,126
Net Cash Flows Used in Investing Activities	(717,819)	(689,747)
Financing Activities:
Cash Dividends on Common Stock	(232,068)	(159,708)
Cash Dividends on Preferred Stock	(3,922)	(3,269)
Increase/(Decrease) in Short-Term Debt	(720,500)	558,500
Issuance of Long-Term Debt	1,350,000	300,000
Retirements of Long-Term Debt	(360,635)	(267,699)
Retirements of Rate Reduction Bonds	(82,139)	(36,439)
Other Financing Activities	(11,634)	(117)
Net Cash Flows Provided by/(Used in) Financing Activities	(60,898)	391,268
Net Increase/(Decrease) in Cash	(9,693)	21,924
Cash - Beginning of Year	45,748	6,559
Cash - End of Year	36,055	28,483
The Connecticut Light And Power Company [Member]
Operating Activities:
Net Income	152,865	60,918
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	87,570	82,588
Deferred Income Tax Expense (Benefit)	99,045	30,874
Pension and PBOP Expense, Net of PBOP Contributions	13,826	12,030
Regulatory (Underrecoveries)/Overrecoveries, Net	(36,902)	(19,596)
Amortization of Regulatory Assets/(Liabilities), Net	11,249	11,257
Other Noncash Income (Expense)	(13,476)	(12,078)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(33,976)	38,253
Taxes Receivable/(Accrued)	(14,081)	39,985
Change in Accounts Payable	(95,487)	(170,151)
Other Current Assets and Liabilities	7,548	(26,579)
Net Cash Flows Provided by Operating Activities	178,181	47,501
Investing Activities:
Investments in Property, Plant and Equipment	(184,875)	(220,712)
Other Investing Activities	884	3,460
Net Cash Flows Used in Investing Activities	(183,991)	(217,252)
Financing Activities:
Cash Dividends on Common Stock	(76,000)	(66,991)
Cash Dividends on Preferred Stock	(2,779)	(2,779)
Increase/(Decrease) in Short-Term Debt	(89,000)	299,000
Issuance of Long-Term Debt	400,000
Increase/(Decrease) in Notes Payable to Affiliate	(215,800)	(53,525)
Other Financing Activities	(6,345)	(1,432)
Net Cash Flows Provided by/(Used in) Financing Activities	10,076	174,273
Net Increase/(Decrease) in Cash	4,266	4,522
Cash - Beginning of Year	1	1
Cash - End of Year	4,267	4,523
NSTAR Electric Company [Member]
Operating Activities:
Net Income	106,153	49,422
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	11,307	46,726
Depreciation	90,882	85,198
Deferred Income Tax Expense (Benefit)	28,750	(16,389)
Pension and PBOP Expense, Net of PBOP Contributions	(5,139)	16,822
Regulatory (Underrecoveries)/Overrecoveries, Net	(33,901)	16,371
Amortization of Regulatory Assets/(Liabilities), Net	100,548	46,024
Amortization of Rate Reduction Bonds	15,054	45,161
Other Noncash Income (Expense)	(47,574)	(25,239)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(60,174)	(19,555)
Inventory	3,294	10,387
Taxes Receivable/(Accrued)	(39,813)	(29,978)
Change in Accounts Payable	(8,686)	(64,317)
Other Current Assets and Liabilities	(11,702)	24,899
IncreaseDecreaseInAccountsPayableRelatedParties	(57,369)	(26,121)
Net Cash Flows Provided by Operating Activities	91,630	159,411
Investing Activities:
Investments in Property, Plant and Equipment	(207,380)	(189,229)
DecreaseInRestrictedCash	38,429	6,867
Other Investing Activities	77	375
Net Cash Flows Used in Investing Activities	(168,874)	(181,987)
Financing Activities:
Cash Dividends on Common Stock	(56,000)	(135,400)
Cash Dividends on Preferred Stock	(1,143)	(980)
Increase/(Decrease) in Short-Term Debt	(23,000)	203,000
Issuance of Long-Term Debt	200,000
Retirements of Long-Term Debt	(1,650)	(825)
Retirements of Rate Reduction Bonds	(43,493)	(43,548)
Net Cash Flows Provided by/(Used in) Financing Activities	74,714	22,247
Net Increase/(Decrease) in Cash	(2,530)	(329)
Cash - Beginning of Year	13,695	9,373
Cash - End of Year	11,165	9,044
Public Service Company Of New Hampshire [Member]
Operating Activities:
Net Income	56,189	42,494
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	45,515	43,018
Deferred Income Tax Expense (Benefit)	25,450	17,885
Pension and PBOP Expense, Net of PBOP Contributions	14,228	13,168
Pension and Other Postretirement Benefit Contributions	(45,721)	(91,990)
Regulatory (Underrecoveries)/Overrecoveries, Net	4,844	3,625
Amortization of Regulatory Assets/(Liabilities), Net	(1,969)	177
Amortization of Rate Reduction Bonds	19,748	27,743
Other Noncash Income (Expense)	3,123	16,543
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	597	3,283
Inventory	(13,289)	17,365
Taxes Receivable/(Accrued)	21,584	(3,776)
Change in Accounts Payable	26,159	(14,171)
Other Current Assets and Liabilities	(17,743)	(5,231)
Net Cash Flows Provided by Operating Activities	138,715	70,133
Investing Activities:
Investments in Property, Plant and Equipment	(109,565)	(120,792)
(Increase) Decrease In Notes Receivable From Affiliated Company	0	55,900
DecreaseInRestrictedCash	22,039	3,111
Other Investing Activities	(13)	(66)
Net Cash Flows Used in Investing Activities	(87,539)	(61,847)
Financing Activities:
Cash Dividends on Common Stock	(34,000)	(58,783)
Increase/(Decrease) in Short-Term Debt	118,900	78,500
Retirements of Long-Term Debt	108,985
Retirements of Rate Reduction Bonds	(29,294)	(27,626)
Other Financing Activities	(225)	(230)
Net Cash Flows Provided by/(Used in) Financing Activities	(53,604)	(8,139)
Net Increase/(Decrease) in Cash	(2,428)	147
Cash - Beginning of Year	2,493	56
Cash - End of Year	65	203
Western Massachusetts Electric Company [Member]
Operating Activities:
Net Income	35,016	25,324
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	18,280	14,691
Deferred Income Tax Expense (Benefit)	33,317	17,708
Regulatory (Underrecoveries)/Overrecoveries, Net	(5,094)	(17,645)
Amortization of Regulatory Assets/(Liabilities), Net	814	(387)
Amortization of Rate Reduction Bonds	7,780	8,776
Other Noncash Income (Expense)	572	1,917
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(8,681)	694
Taxes Receivable/(Accrued)	21,081	533
Change in Accounts Payable	21,389	(433)
Other Current Assets and Liabilities	(5,166)	(7,334)
Net Cash Flows Provided by Operating Activities	119,308	43,844
Investing Activities:
Investments in Property, Plant and Equipment	(96,051)	(152,687)
Proceeds from Sales of Marketable Securities	41,604	45,516
Purchases of Marketable Securities	(41,961)	(45,889)
(Increase) Decrease In Notes Receivable From Affiliated Company		(11,000)
Other Investing Activities	4,601	1,096
Net Cash Flows Used in Investing Activities	(91,807)	(140,964)
Financing Activities:
Cash Dividends on Common Stock	(20,000)	(9,432)
Increase/(Decrease) in Short-Term Debt	0	110,000
Increase/(Decrease) in Notes Payable to Affiliate	3,300	5,400
Retirements of Rate Reduction Bonds	(9,352)	(8,813)
Other Financing Activities	(31)	(35)
Net Cash Flows Provided by/(Used in) Financing Activities	(26,083)	97,120
Net Increase/(Decrease) in Cash	1,418	0
Cash - Beginning of Year	1
Cash - End of Year	$ 1,419	$ 1