CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating Activities:
Net Income	$ 146,974	$ 194,303
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	13,384	9,374
Depreciation	225,324	147,588
Deferred Income Tax Expense (Benefit)	59,509	95,293
Pension, SERP, and PBOP Expense, Net of PBOP Contributions	97,378	69,654
Pension and PBOP Contributions	(164,294)	(37,530)
Regulatory (Underrecoveries)/Overrecoveries, Net	(54,491)	41,612
Amortization of Regulatory Assets/(Liabilities), Net	31,016	50,491
Amortization of Rate Reduction Bonds	59,100	34,367
Changes in Derivative Assets and Liabilities	(5,090)	(9,272)
Other Noncash Income (Expense)	11,226	(7,192)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	83,395	80,696
Inventory	40,695	12,992
Taxes Receivable/(Accrued)	17,709	48,933
Change in Accounts Payable	(176,533)	(23,981)
Other Current Assets and Liabilities	(64,899)	(20,633)
Net Cash Flows (Used in)/ Provided by Operating Activities	320,403	686,695
Investing Activities:
Investments in Property, Plant and Equipment	(690,376)	(468,526)
Proceeds from Sales of Marketable Securities	132,580	72,369
Purchases of Marketable Securities	(143,225)	(73,564)
Proceeds From Sale Of Property Plant And Equipment	0	46,841
Other Investing Activities	11,274	(4,828)
Net Cash Flows Used in Investing Activities	(689,747)	(427,708)
Financing Activities:
Cash Dividends on Common Stock	(159,708)	(97,207)
Cash Dividends on Preferred Stock	(3,269)	(2,779)
Increase/(Decrease) in Short-Term Debt	558,500	(130,000)
Issuance of Long-Term Debt	300,000	122,000
Retirements of Long-Term Debt	(267,699)	(124,086)
Retirements of Rate Reduction Bonds	(36,439)	(34,320)
Other Financing Activities	(117)	(883)
Net Cash Flows Provided by/(Used in) Financing Activities	391,268	(267,275)
Net Increase/(Decrease) in Cash	21,924	(8,288)
Cash - Beginning of Year	6,559	23,395
Cash - End of Year	28,483	15,107
The Connecticut Light And Power Company [Member]
Operating Activities:
Net Income	60,918	116,972
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	743	2,252
Depreciation	82,588	77,917
Deferred Income Tax Expense (Benefit)	30,874	60,425
Pension, SERP, and PBOP Expense, Net of PBOP Contributions	12,030	9,868
Regulatory (Underrecoveries)/Overrecoveries, Net	(19,596)	24,852
Amortization of Regulatory Assets/(Liabilities), Net	11,257	32,339
Other Noncash Income (Expense)	(12,821)	(17,752)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	38,253	34,192
Inventory	(2,457)	(11,761)
Taxes Receivable/(Accrued)	39,985	31,797
Change in Accounts Payable	(170,151)	(12,078)
Other Current Assets and Liabilities	(24,122)	9,968
Net Cash Flows (Used in)/ Provided by Operating Activities	47,501	358,991
Investing Activities:
Investments in Property, Plant and Equipment	(220,712)	(201,966)
Decrease/(Increase) in NU Money Pool Lending	0	(24,125)
Proceeds From Sale Of Property Plant And Equipment	0	46,841
Other Investing Activities	3,460	(6,489)
Net Cash Flows Used in Investing Activities	(217,252)	(185,739)
Financing Activities:
Cash Dividends on Common Stock	(66,991)	(168,744)
Cash Dividends on Preferred Stock	(2,779)	(2,779)
Increase/(Decrease) in Short-Term Debt	299,000	0
Increase/(Decrease) in NU Money Pool Borrowings	(53,525)	(6,225)
Other Financing Activities	(1,432)	(188)
Net Cash Flows Provided by/(Used in) Financing Activities	174,273	(177,936)
Net Increase/(Decrease) in Cash	4,522	(4,684)
Cash - Beginning of Year	1	9,762
Cash - End of Year	4,523	5,078
Public Service Company Of New Hampshire [Member]
Operating Activities:
Net Income	42,494	49,129
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	3,378	3,303
Depreciation	43,018	36,030
Deferred Income Tax Expense (Benefit)	17,885	20,773
Pension, SERP, and PBOP Expense, Net of PBOP Contributions	13,168	14,406
Pension and PBOP Contributions	(91,990)	(18,469)
Regulatory (Underrecoveries)/Overrecoveries, Net	3,625	726
Amortization of Regulatory Assets/(Liabilities), Net	177	18,032
Amortization of Rate Reduction Bonds	27,743	26,139
Other Noncash Income (Expense)	13,165	(2,545)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	3,283	12,844
Inventory	17,365	11,915
Taxes Receivable/(Accrued)	(3,776)	9,767
Change in Accounts Payable	(14,171)	(8,611)
Other Current Assets and Liabilities	(5,231)	(16,885)
Net Cash Flows (Used in)/ Provided by Operating Activities	70,133	156,554
Investing Activities:
Investments in Property, Plant and Equipment	(120,792)	(111,459)
Decrease/(Increase) in NU Money Pool Lending	55,900	0
Other Investing Activities	3,045	1,928
Net Cash Flows Used in Investing Activities	(61,847)	(109,531)
Financing Activities:
Cash Dividends on Common Stock	(58,783)	(29,414)
Increase/(Decrease) in Short-Term Debt	65,000	(8,000)
Issuance of Long-Term Debt	0	122,000
Increase/(Decrease) in NU Money Pool Borrowings	13,500	(4,100)
Retirements of Long-Term Debt	0	(119,800)
Retirements of Rate Reduction Bonds	(27,626)	(26,052)
Capital Contributions from NU Parent	0	20,000
Other Financing Activities	(230)	(1,803)
Net Cash Flows Provided by/(Used in) Financing Activities	(8,139)	(47,169)
Net Increase/(Decrease) in Cash	147	(146)
Cash - Beginning of Year	56	2,559
Cash - End of Year	203	2,413
Western Massachusetts Electric Company [Member]
Operating Activities:
Net Income	25,324	18,137
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	790	1,860
Depreciation	14,691	12,963
Deferred Income Tax Expense (Benefit)	17,708	7,004
Regulatory (Underrecoveries)/Overrecoveries, Net	(17,645)	9,222
Amortization of Regulatory Assets/(Liabilities), Net	(387)	728
Amortization of Rate Reduction Bonds	8,776	8,228
Other Noncash Income (Expense)	1,127	(2,034)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	694	405
Inventory	(2,793)	(398)
Taxes Receivable/(Accrued)	533	9,523
Change in Accounts Payable	(433)	1,021
Other Current Assets and Liabilities	(4,541)	(281)
Net Cash Flows (Used in)/ Provided by Operating Activities	43,844	66,378
Investing Activities:
Investments in Property, Plant and Equipment	(152,687)	(76,898)
Proceeds from Sales of Marketable Securities	45,516	57,746
Purchases of Marketable Securities	(45,889)	(57,888)
Decrease/(Increase) in NU Money Pool Lending	11,000	0
Other Investing Activities	1,096	(792)
Net Cash Flows Used in Investing Activities	(140,964)	(77,832)
Financing Activities:
Cash Dividends on Common Stock	(9,432)	(13,153)
Increase/(Decrease) in Short-Term Debt	110,000	20,000
Increase/(Decrease) in NU Money Pool Borrowings	5,400	7,700
Retirements of Rate Reduction Bonds	(8,813)	(8,268)
Capital Contributions from NU Parent	0	5,186
Other Financing Activities	(35)	(11)
Net Cash Flows Provided by/(Used in) Financing Activities	97,120	11,454
Net Increase/(Decrease) in Cash	0	0
Cash - Beginning of Year	1	1
Cash - End of Year	1	1
NSTAR Electric Company [Member]
Operating Activities:
Net Income	49,422	103,547
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	46,726	8,284
Depreciation	85,198	83,157
Deferred Income Tax Expense (Benefit)	(17,069)	3,413
Pension, SERP, and PBOP Expense, Net of PBOP Contributions	16,822	(31,298)
Regulatory (Underrecoveries)/Overrecoveries, Net	16,371	70,319
Amortization of Regulatory Assets/(Liabilities), Net	46,024	29,669
Amortization of Rate Reduction Bonds	45,161	45,161
Other Noncash Income (Expense)	(24,559)	8,807
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(19,555)	(33,830)
Inventory	10,387	(4,673)
Taxes Receivable/(Accrued)	(29,978)	174,103
Change in Accounts Payable	(64,317)	(100,840)
Other Current Assets and Liabilities	(1,222)	4,125
Net Cash Flows (Used in)/ Provided by Operating Activities	159,411	359,944
Investing Activities:
Investments in Property, Plant and Equipment	(189,229)	(156,842)
Other Investing Activities	7,242	20,641
Net Cash Flows Used in Investing Activities	(181,987)	(136,201)
Financing Activities:
Cash Dividends on Common Stock	(135,400)	(113,300)
Cash Dividends on Preferred Stock	(980)	(980)
Increase/(Decrease) in Short-Term Debt	203,000	(64,500)
Retirements of Long-Term Debt	(825)	(825)
Retirements of Rate Reduction Bonds	(43,548)	(43,581)
Net Cash Flows Provided by/(Used in) Financing Activities	22,247	(223,186)
Net Increase/(Decrease) in Cash	(329)	557
Cash - Beginning of Year	9,373	8,964
Cash - End of Year	$ 9,044	$ 9,521