CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating Revenues	$ 1,099,623	$ 1,235,251
Operating Expenses:
Fuel, Purchased and Net Interchange Power	398,013	474,109
Other Operating Expenses	225,958	251,978
Maintenance	69,826	67,764
Depreciation	80,839	73,951
Amortization of Regulatory Assets/(Liabilities), Net	6,209	34,407
Amortization of Rate Reduction Bonds	18,347	17,282
Taxes Other Than Income Taxes	86,038	88,403
Total Operating Expenses	885,230	1,007,894
Operating Income	214,393	227,357
Interest Expense:
Interest on Long-Term Debt	59,968	57,399
Interest on Rate Reduction Bonds	1,431	2,578
Other Interest	5,048	(1,428)
Total Interest Expense	66,447	58,549
Other Income/(Loss), Net	8,773	10,313
Income Before Income Tax Expense	156,719	179,121
Income Tax Expense	55,964	63,537
Net Income	100,755	115,584
Net Income Attributable to Noncontrolling Interests	1,493	1,429
Net Income Attributable to Controlling Interests	99,262	114,155
Earnings Per Share Basic And Diluted	$ 0.56	$ 0.64
Common Stock Dividends Per Share Declared	$ 0.29	$ 0.28
Weighted Average Common Shares Outstanding:
Basic	178,055,716	177,188,207
Diluted	178,437,453	177,480,996
The Connecticut Light And Power Company [Member]
Operating Revenues	591,965	673,682
Operating Expenses:
Fuel, Purchased and Net Interchange Power	223,835	255,369
Other Operating Expenses	108,824	134,262
Maintenance	42,788	40,782
Depreciation	41,070	39,475
Amortization of Regulatory Assets/(Liabilities), Net	8,313	19,343
Taxes Other Than Income Taxes	55,270	58,468
Total Operating Expenses	480,100	547,699
Operating Income	111,865	125,983
Interest Expense:
Interest on Long-Term Debt	31,521	33,328
Other Interest	1,987	(3,575)
Total Interest Expense	33,508	29,753
Other Income/(Loss), Net	5,300	4,606
Income Before Income Tax Expense	83,657	100,836
Income Tax Expense	29,672	36,499
Net Income	53,985	64,337
Public Service Company Of New Hampshire [Member]
Operating Revenues	242,997	269,470
Operating Expenses:
Fuel, Purchased and Net Interchange Power	73,197	87,132
Other Operating Expenses	56,999	56,422
Maintenance	19,413	18,704
Depreciation	21,208	17,907
Amortization of Regulatory Assets/(Liabilities), Net	(2,622)	15,567
Amortization of Rate Reduction Bonds	13,930	13,135
Taxes Other Than Income Taxes	15,486	13,667
Total Operating Expenses	197,611	222,534
Operating Income	45,386	46,936
Interest Expense:
Interest on Long-Term Debt	11,563	8,624
Interest on Rate Reduction Bonds	1,016	1,893
Other Interest	234	(60)
Total Interest Expense	12,813	10,457
Other Income/(Loss), Net	2,042	4,459
Income Before Income Tax Expense	34,615	40,938
Income Tax Expense	13,353	13,474
Net Income	21,262	27,464
Western Massachusetts Electric Company [Member]
Operating Revenues	114,025	106,684
Operating Expenses:
Fuel, Purchased and Net Interchange Power	39,504	40,204
Other Operating Expenses	24,019	26,230
Maintenance	4,724	4,771
Depreciation	7,697	6,338
Amortization of Regulatory Assets/(Liabilities), Net	121	(600)
Amortization of Rate Reduction Bonds	4,418	4,146
Taxes Other Than Income Taxes	4,882	4,543
Total Operating Expenses	85,365	85,632
Operating Income	28,660	21,052
Interest Expense:
Interest on Long-Term Debt	5,766	4,754
Interest on Rate Reduction Bonds	415	684
Other Interest	214	136
Total Interest Expense	6,395	5,574
Other Income/(Loss), Net	1,092	739
Income Before Income Tax Expense	23,357	16,217
Income Tax Expense	9,171	6,251
Net Income	$ 14,186	$ 9,966