CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Operating Activities:
Net Income	$ 285,734	$ 262,884
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	12,435	24,632
Depreciation	222,784	228,685
Deferred Income Taxes	133,528	105,070
Pension and PBOP Expense, Net of PBOP Contributions	103,106	74,744
Pension and Other Postretirement Benefit Contributions	(159,220)	(78,035)
Regulatory (Underrecoveries)/Overrecoveries, Net	(26,001)	44,479
Amortization of Regulatory Assets/(Liabilities), Net	88,409	50,908
Amortization of Rate Reduction Bonds	52,047	175,000
Changes in Derivative Assets and Liabilities	(33,767)	(9,228)
Other Noncash Income (Expense)	(14,802)	(46,190)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	61,657	20,905
Inventory	(4,072)	33,337
Taxes Receivable/(Accrued)	109,410	(12,904)
Change in Accounts Payable	66,618	(59,601)
Other Current Assets and Liabilities	(9,419)	28,961
Net Cash Flows Provided by Operating Activities	888,447	843,647
Investing Activities:
Investments in Property, Plant and Equipment	(749,060)	(677,579)
Proceeds from Sales of Marketable Securities	116,463	146,305
Purchases of Marketable Securities	(118,251)	(148,075)
Proceeds From Sale Of Property Plant And Equipment	46,841	0
Other Investing Activities	(5,849)	(10,412)
Net Cash Flows Used in Investing Activities	(709,856)	(689,761)
Financing Activities:
Cash Dividends on Common Stock	(145,865)	(135,349)
Cash Dividends on Preferred Stock	(4,169)	(4,169)
Increase/(Decrease) in Short-Term Debt	(237,000)	55,687
Issuance of Long-Term Debt	382,000	145,000
Retirements of Long-Term Debt	(124,086)	(4,286)
Retirements of Rate Reduction Bonds	(51,198)	(195,724)
Other Financing Activities	(4,947)	(818)
Net Cash Flows Provided by/(Used in) Financing Activities	(185,265)	(139,659)
Net Increase/(Decrease) in Cash	(6,674)	14,227
Cash - Beginning of Year	23,395	26,952
Cash - End of Year	16,721	41,179
The Connecticut Light and Power Company [Member]
Operating Activities:
Net Income	183,500	161,543
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	2,115	7,088
Depreciation	117,629	133,568
Deferred Income Taxes	67,948	49,636
Pension and PBOP Expense, Net of PBOP Contributions	10,473	388
Regulatory (Underrecoveries)/Overrecoveries, Net	(50,234)	57,696
Amortization of Regulatory Assets/(Liabilities), Net	48,736	55,308
Amortization of Rate Reduction Bonds	0	125,985
Other Noncash Income (Expense)	(22,435)	(38,073)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	26,164	2,653
Inventory	(12,669)	3,331
Taxes Receivable/(Accrued)	64,779	(13,016)
Change in Accounts Payable	73,809	(55,383)
Other Current Assets and Liabilities	(23,245)	36
Net Cash Flows Provided by Operating Activities	486,570	490,760
Investing Activities:
Investments in Property, Plant and Equipment	(305,595)	(274,193)
Decrease/(Increase) in NU Money Pool Lending	(6,925)	97,775
Proceeds From Sale Of Property Plant And Equipment	46,841	0
Other Investing Activities	(6,693)	205
Net Cash Flows Used in Investing Activities	(272,372)	(176,213)
Financing Activities:
Cash Dividends on Common Stock	(205,981)	(181,841)
Cash Dividends on Preferred Stock	(4,169)	(4,169)
Increase/(Decrease) in NU Money Pool Borrowings	(6,225)	26,325
Retirements of Rate Reduction Bonds	0	(147,533)
Other Financing Activities	(349)	(256)
Net Cash Flows Provided by/(Used in) Financing Activities	(216,724)	(307,474)
Net Increase/(Decrease) in Cash	(2,526)	7,073
Cash - Beginning of Year	9,762	45
Cash - End of Year	7,236	7,118
Public Service Company of New Hampshire [Member]
Operating Activities:
Net Income	74,763	66,180
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	5,202	7,237
Depreciation	54,432	49,443
Deferred Income Taxes	51,809	31,876
Pension and PBOP Expense, Net of PBOP Contributions	21,568	20,767
Pension and Other Postretirement Benefit Contributions	(99,780)	(51,060)
Regulatory (Underrecoveries)/Overrecoveries, Net	2,581	(5,450)
Amortization of Regulatory Assets/(Liabilities), Net	35,303	(2,809)
Amortization of Rate Reduction Bonds	39,748	37,481
Changes in Derivative Assets and Liabilities	(18,072)	0
Insurance Proceeds	0	10,000
Other Noncash Income (Expense)	(15,501)	(32,525)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	9,332	(8,973)
Inventory	11,981	28,188
Taxes Receivable/(Accrued)	18,758	15,066
Change in Accounts Payable	(6,905)	(11,599)
Other Current Assets and Liabilities	14,613	21,852
Net Cash Flows Provided by Operating Activities	199,832	175,674
Investing Activities:
Investments in Property, Plant and Equipment	(167,383)	(217,954)
Decrease/(Increase) in NU Money Pool Lending	(50,300)	0
Other Investing Activities	1,026	(7,753)
Net Cash Flows Used in Investing Activities	(216,657)	(225,707)
Financing Activities:
Cash Dividends on Common Stock	(44,121)	(37,938)
Increase/(Decrease) in Short-Term Debt	(30,000)	0
Issuance of Long-Term Debt	282,000	0
Increase/(Decrease) in NU Money Pool Borrowings	(47,900)	(100)
Retirements of Long-Term Debt	(119,800)	0
Retirements of Rate Reduction Bonds	(38,881)	(36,635)
Capital Contributions from NU Parent	20,000	123,551
Other Financing Activities	(4,162)	(176)
Net Cash Flows Provided by/(Used in) Financing Activities	17,136	48,702
Net Increase/(Decrease) in Cash	311	(1,331)
Cash - Beginning of Year	2,559	1,974
Cash - End of Year	2,870	643
Western Massachusetts Electric Company [Member]
Operating Activities:
Net Income	26,571	18,245
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Bad Debt Expense	2,352	5,602
Depreciation	19,644	17,658
Deferred Income Taxes	9,323	4,712
Regulatory (Underrecoveries)/Overrecoveries, Net	20,757	(8,696)
Amortization of Regulatory Assets/(Liabilities), Net	4,584	445
Amortization of Rate Reduction Bonds	12,299	11,534
Changes in Derivative Assets and Liabilities	(6,859)	0
Other Noncash Income (Expense)	(3,396)	(4,961)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(7,804)	(2,896)
Inventory	67	(878)
Taxes Receivable/(Accrued)	10,675	1,203
Change in Accounts Payable	4,294	(9,900)
Other Current Assets and Liabilities	(3,830)	(1,381)
Net Cash Flows Provided by Operating Activities	88,677	30,687
Investing Activities:
Investments in Property, Plant and Equipment	(153,470)	(77,710)
Proceeds from Sales of Marketable Securities	96,134	94,575
Purchases of Marketable Securities	(96,312)	(94,896)
Decrease/(Increase) in NU Money Pool Lending	(70,700)	0
Other Investing Activities	(1,664)	(754)
Net Cash Flows Used in Investing Activities	(226,012)	(78,785)
Financing Activities:
Cash Dividends on Common Stock	(19,729)	(11,162)
Issuance of Long-Term Debt	100,000	95,000
Increase/(Decrease) in NU Money Pool Borrowings	(20,400)	(125,900)
Retirements of Rate Reduction Bonds	(12,318)	(11,557)
Capital Contributions from NU Parent	91,812	102,600
Other Financing Activities	(1,761)	(883)
Net Cash Flows Provided by/(Used in) Financing Activities	137,604	48,098
Net Increase/(Decrease) in Cash	269	0
Cash - Beginning of Year	1	1
Cash - End of Year	$ 270	$ 1