CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating Revenues	$ 1,933,105	$ 1,892,532	$ 6,263,597	$ 5,860,736
Operating Expenses:
Purchased Power and Transmission	702,640	716,631	2,549,807	2,318,993
Operations and Maintenance	327,283	344,092	977,306	1,069,015
Depreciation	167,884	153,210	495,389	456,224
Amortization of Regulatory Assets/(Liabilities), Net	(16,851)	(22,531)	42,587	31,826
Energy Efficiency Programs	132,107	118,693	380,559	360,228
Taxes Other Than Income Taxes	150,804	141,527	439,221	421,862
Total Operating Expenses	1,463,867	1,451,622	4,884,869	4,658,148
Operating Income	469,238	440,910	1,378,728	1,202,588
Interest Expense:
Total Interest Expense	92,534	89,738	279,635	272,208
Other Income/(Loss), Net	5,241	11,860	23,866	19,054
Income Before Income Tax Expense	381,945	363,032	1,122,959	949,434
Income Tax Expense	144,146	126,539	420,640	345,858
Net Income	237,799	236,493	702,319	603,576
Net Income Attributable to Noncontrolling Interests	1,879	1,879	5,639	5,639
Net Income Attributable to Controlling Interests	$ 235,920	$ 234,614	$ 696,680	$ 597,937
Basic Earnings Per Common Share	$ 0.74	$ 0.74	$ 2.20	$ 1.89
Diluted Earnings Per Common Share	0.74	0.74	2.19	1.89
Common Stock Dividends Per Share Declared	$ 0.42	$ 0.39	$ 1.25	$ 1.18
Weighted Average Common Shares Outstanding:
Basic	317,452,212	316,340,691	317,296,107	315,941,904
Diluted	318,405,269	317,554,925	318,396,042	317,186,490
The Connecticut Light And Power Company [Member]
Operating Revenues	$ 704,262	$ 695,642	$ 2,175,733	$ 2,017,580
Operating Expenses:
Purchased Power and Transmission	274,762	255,787	861,562	736,952
Operations and Maintenance	122,280	127,285	358,324	368,562
Depreciation	54,809	46,886	159,903	139,598
Amortization of Regulatory Assets/(Liabilities), Net	(22,859)	13,098	17,917	62,644
Energy Efficiency Programs	42,590	41,399	119,360	119,389
Taxes Other Than Income Taxes	71,563	64,994	201,743	194,105
Total Operating Expenses	543,145	549,449	1,718,809	1,621,250
Operating Income	161,117	146,193	456,924	396,330
Interest Expense:
Total Interest Expense	36,716	38,735	109,463	110,448
Other Income/(Loss), Net	2,356	6,456	8,576	10,658
Income Before Income Tax Expense	126,757	113,914	356,037	296,540
Income Tax Expense	46,569	30,038	127,845	95,980
Net Income	80,188	83,876	228,192	200,560
NSTAR Electric Company [Member]
Operating Revenues	750,724	727,909	2,134,728	1,955,609
Operating Expenses:
Purchased Power and Transmission	299,040	317,784	984,035	879,773
Operations and Maintenance	83,486	79,705	228,740	244,610
Depreciation	49,101	47,455	146,818	140,996
Amortization of Regulatory Assets/(Liabilities), Net	2,257	(15,063)	(10,643)	(916)
Energy Efficiency Programs	67,693	56,915	164,843	145,499
Taxes Other Than Income Taxes	34,982	34,513	95,821	99,121
Total Operating Expenses	536,559	521,309	1,609,614	1,509,083
Operating Income	214,165	206,600	525,114	446,526
Interest Expense:
Total Interest Expense	18,992	17,338	57,218	59,091
Other Income/(Loss), Net	513	3,287	3,649	3,011
Income Before Income Tax Expense	195,686	192,549	471,545	390,446
Income Tax Expense	77,062	76,975	187,397	156,655
Net Income	118,624	115,574	284,148	233,791
Public Service Company Of New Hampshire [Member]
Operating Revenues	234,364	223,664	761,086	735,123
Operating Expenses:
Purchased Power and Transmission	53,017	64,397	200,533	247,992
Operations and Maintenance	65,190	65,563	200,085	198,025
Depreciation	26,592	24,568	77,989	73,247
Amortization of Regulatory Assets/(Liabilities), Net	1,967	(9,734)	29,148	(17,565)
Energy Efficiency Programs	3,873	3,766	11,001	10,897
Taxes Other Than Income Taxes	20,104	18,702	61,435	53,051
Total Operating Expenses	170,743	167,262	580,191	565,647
Operating Income	63,621	56,402	180,895	169,476
Interest Expense:
Total Interest Expense	11,647	11,024	34,582	33,995
Other Income/(Loss), Net	685	461	2,313	1,673
Income Before Income Tax Expense	52,659	45,839	148,626	137,154
Income Tax Expense	20,158	17,603	56,135	52,199
Net Income	32,501	28,236	92,491	84,955
Western Massachusetts Electric Company [Member]
Operating Revenues	125,093	118,145	403,151	363,843
Operating Expenses:
Purchased Power and Transmission	36,465	43,926	149,182	130,977
Operations and Maintenance	21,762	20,820	61,651	67,085
Depreciation	11,196	10,506	32,420	31,144
Amortization of Regulatory Assets/(Liabilities), Net	3,930	(8,519)	11,194	(7,778)
Energy Efficiency Programs	12,107	10,983	32,701	33,096
Taxes Other Than Income Taxes	9,599	9,200	28,430	25,679
Total Operating Expenses	95,059	86,916	315,578	280,203
Operating Income	30,034	31,229	87,573	83,640
Interest Expense:
Total Interest Expense	5,901	6,576	19,014	18,929
Other Income/(Loss), Net	587	502	2,406	1,670
Income Before Income Tax Expense	24,720	25,155	70,965	66,381
Income Tax Expense	9,749	10,490	28,555	26,596
Net Income	$ 14,971	$ 14,665	$ 42,410	$ 39,785