CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues	$ 1,817,061	$ 1,677,614	$ 4,330,491	$ 3,968,204
Operating Expenses:
Purchased Power and Transmission	685,118	624,211	1,847,167	1,602,362
Operations and Maintenance	316,641	373,234	650,024	724,922
Depreciation	163,668	152,207	327,505	303,014
Amortization of Regulatory Assets/(Liabilities), Net	(1,166)	(3,542)	59,438	54,356
Energy Efficiency Programs	101,850	102,711	248,452	241,536
Taxes Other Than Income Taxes	138,935	134,803	288,415	280,335
Total Operating Expenses	1,405,046	1,383,624	3,421,001	3,206,525
Operating Income	412,015	293,990	909,490	761,679
Interest Expense:
Interest on Long-Term Debt	88,021	87,491	175,735	174,868
Other Interest	4,238	5,004	11,367	7,603
Total Interest Expense	92,259	92,495	187,102	182,471
Other Income/(Loss), Net	12,899	5,526	18,626	7,194
Income Before Income Tax Expense	332,655	207,021	741,014	586,402
Income Tax Expense	123,268	77,774	276,494	219,319
Net Income	209,387	129,247	464,520	367,083
Net Income Attributable to Noncontrolling Interests	1,880	1,880	3,759	3,759
Net Income Attributable to Controlling Interests	$ 207,507	$ 127,367	$ 460,761	$ 363,324
Earnings Per Share Basic And Diluted	$ 0.65	$ 0.40	$ 1.45	$ 1.15
Common Stock Dividends Per Share Declared	$ 0.42	$ 0.39	$ 0.84	$ 0.79
Weighted Average Common Shares Outstanding:
Basic	317,613,166	315,950,510	317,352,004	315,742,511
Diluted	318,559,568	317,112,801	318,525,378	317,002,461
The Connecticut Light And Power Company [Member]
Operating Revenues	$ 666,554	$ 587,324	$ 1,471,471	$ 1,321,938
Operating Expenses:
Purchased Power and Transmission	253,180	199,785	586,799	481,165
Operations and Maintenance	118,687	131,762	236,044	241,276
Depreciation	52,191	46,581	105,094	92,712
Amortization of Regulatory Assets/(Liabilities), Net	(7,530)	19,615	40,776	49,546
Energy Efficiency Programs	33,963	35,296	76,770	77,991
Taxes Other Than Income Taxes	62,102	62,159	130,181	129,111
Total Operating Expenses	512,593	495,198	1,175,664	1,071,801
Operating Income	153,961	92,126	295,807	250,137
Interest Expense:
Interest on Long-Term Debt	33,423	34,639	66,904	67,548
Other Interest	2,701	2,831	5,844	4,165
Total Interest Expense	36,124	37,470	72,748	71,713
Other Income/(Loss), Net	4,062	3,130	6,221	4,202
Income Before Income Tax Expense	121,899	57,786	229,280	182,626
Income Tax Expense	43,129	20,401	81,276	65,942
Net Income	78,770	37,385	148,004	116,684
NSTAR Electric Company [Member]
Operating Revenues	617,196	561,513	1,384,004	1,227,701
Operating Expenses:
Purchased Power and Transmission	283,129	242,907	684,995	561,989
Operations and Maintenance	69,430	78,981	145,254	164,905
Depreciation	48,949	46,915	97,716	93,540
Amortization of Regulatory Assets/(Liabilities), Net	(7,336)	(1,517)	(12,901)	14,147
Energy Efficiency Programs	41,733	40,255	97,150	88,584
Taxes Other Than Income Taxes	29,876	32,458	60,841	64,610
Total Operating Expenses	465,781	439,999	1,073,055	987,775
Operating Income	151,415	121,514	310,949	239,926
Interest Expense:
Interest on Long-Term Debt	18,579	19,732	37,225	40,489
Other Interest	(798)	960	1,002	1,263
Total Interest Expense	17,781	20,692	38,227	41,752
Other Income/(Loss), Net	2,533	(246)	3,136	(277)
Income Before Income Tax Expense	136,167	100,576	275,858	197,897
Income Tax Expense	54,204	40,447	110,335	79,681
Net Income	81,963	60,129	165,523	118,216
Public Service Company Of New Hampshire [Member]
Operating Revenues	241,875	211,626	526,722	511,458
Operating Expenses:
Purchased Power and Transmission	47,938	68,349	147,516	183,595
Operations and Maintenance	76,468	70,249	134,895	132,462
Depreciation	25,751	24,464	51,397	48,679
Amortization of Regulatory Assets/(Liabilities), Net	12,050	(20,393)	27,181	(7,831)
Energy Efficiency Programs	3,356	3,292	7,128	7,131
Taxes Other Than Income Taxes	22,249	16,635	41,331	34,348
Total Operating Expenses	187,812	162,596	409,448	398,384
Operating Income	54,063	49,030	117,274	113,074
Interest Expense:
Interest on Long-Term Debt	11,359	11,390	22,758	22,916
Other Interest	303	(391)	177	55
Total Interest Expense	11,662	10,999	22,935	22,971
Other Income/(Loss), Net	1,245	946	1,628	1,212
Income Before Income Tax Expense	43,646	38,977	95,967	91,315
Income Tax Expense	15,701	14,897	35,977	34,597
Net Income	27,945	24,080	59,990	56,718
Western Massachusetts Electric Company [Member]
Operating Revenues	125,194	108,289	278,058	245,698
Operating Expenses:
Purchased Power and Transmission	43,055	37,619	112,716	87,050
Operations and Maintenance	20,104	23,686	39,889	46,265
Depreciation	10,848	10,317	21,223	20,638
Amortization of Regulatory Assets/(Liabilities), Net	3,336	343	7,264	741
Energy Efficiency Programs	9,519	10,249	20,594	22,114
Taxes Other Than Income Taxes	9,398	8,396	18,833	16,479
Total Operating Expenses	96,260	90,610	220,519	193,287
Operating Income	28,934	17,679	57,539	52,411
Interest Expense:
Interest on Long-Term Debt	6,015	6,104	12,060	12,165
Other Interest	276	603	1,052	188
Total Interest Expense	6,291	6,707	13,112	12,353
Other Income/(Loss), Net	1,245	594	1,819	1,168
Income Before Income Tax Expense	23,888	11,566	46,246	41,226
Income Tax Expense	9,693	4,548	18,807	16,106
Net Income	$ 14,195	$ 7,018	$ 27,439	$ 25,120