Western Massachusetts Electric 10-Q 4 Nov 16 2016 Q3 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	9 Months Ended
	Sep. 30, 2016	Oct. 31, 2016
Document And Entity [Line Items]
Entity Registrant Name	Eversource Energy
Entity Central Index Key	72,741
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Amendment Flag	false
Trading Symbol	ES
Entity Common Stock, Shares Outstanding (in shares)		316,885,808
The Connecticut Light And Power Company [Member]
Document And Entity [Line Items]
Entity Registrant Name	The Connecticut Light and Power Company
Entity Central Index Key	23,426
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		6,035,205
NSTAR Electric Company [Member]
Document And Entity [Line Items]
Entity Registrant Name	NSTAR Electric Company
Entity Central Index Key	13,372
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		100
Public Service Company Of New Hampshire [Member]
Document And Entity [Line Items]
Entity Registrant Name	Public Service Company of New Hampshire
Entity Central Index Key	315,256
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		301
Western Massachusetts Electric Company [Member]
Document And Entity [Line Items]
Entity Registrant Name	Western Massachusetts Electric Company
Entity Central Index Key	106,170
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		434,653

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current Assets:
Cash and Cash Equivalents	$ 40,056	$ 23,947
Receivables, Net	963,279	775,480
Unbilled Revenues	187,749	202,647
Taxes Receivable	4,527	305,359
Fuel, Materials, Supplies and Inventory	311,051	336,476
Regulatory Assets	752,378	845,843
Prepayments and Other Current Assets	155,612	129,034
Total Current Assets	2,414,652	2,618,786
Property, Plant and Equipment, Net	20,807,943	19,892,441
Deferred Debits and Other Assets:
Regulatory Assets	3,469,879	3,737,960
Goodwill	3,519,401	3,519,401
Marketable Securities	525,809	516,478
Other Long-Term Assets	344,653	295,243
Total Deferred Debits and Other Assets	7,859,742	8,069,082
Total Assets	31,082,337	30,580,309
Current Liabilities:
Notes Payable	734,500	1,160,953
Long-Term Debt - Current Portion	373,883	228,883
Accounts Payable	679,505	813,646
Obligations to Third Party Suppliers	166,845	128,564
Regulatory Liabilities	160,442	107,759
Other Current Liabilities	526,853	549,985
Total Current Liabilities	2,642,028	2,989,790
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	5,442,856	5,147,678
Regulatory Liabilities	550,162	513,595
Derivative Liabilities	427,382	337,102
Accrued Pension, SERP and PBOP	1,116,240	1,407,288
Other Long-Term Liabilities	875,589	871,499
Total Deferred Credits and Other Liabilities	8,412,229	8,277,162
Capitalization:
Long-Term Debt	9,235,128	8,805,574
Noncontrolling Interest - Preferred Stock of Subsidiaries	155,568	155,568
Common Shareholders' Equity:
Common Shares	1,669,392	1,669,313
Capital Surplus, Paid In	6,256,580	6,262,368
Retained Earnings	3,087,006	2,797,355
Accumulated Other Comprehensive Income (Loss)	(65,617)	(66,844)
Treasury Stock	(309,977)	(309,977)
Common Stockholder's Equity	10,637,384	10,352,215
Total Capitalization	20,028,080	19,313,357
Total Liabilities and Capitalization	31,082,337	30,580,309
The Connecticut Light And Power Company [Member]
Current Assets:
Cash and Cash Equivalents	8,607	1,057
Receivables, Net	425,421	352,536
Accounts Receivable from Affiliated Companies	24,012	21,214
Unbilled Revenues	87,771	99,879
Taxes Receivable	0	137,643
Regulatory Assets	267,733	268,318
Materials and Supplies	51,598	43,124
Prepaid Property Taxes	54,619	18,019
Prepayments and Other Current Assets	15,439	14,215
Total Current Assets	935,200	956,005
Property, Plant and Equipment, Net	7,453,200	7,156,809
Deferred Debits and Other Assets:
Regulatory Assets	1,398,610	1,369,028
Other Long-Term Assets	131,049	111,115
Total Deferred Debits and Other Assets	1,529,659	1,480,143
Total Assets	9,918,059	9,592,957
Current Liabilities:
Notes Payable to Eversource Parent	108,500	277,400
Long-Term Debt - Current Portion	250,000	0
Accounts Payable	228,744	267,764
Accounts Payable to Affiliated Companies	63,718	66,456
Obligations to Third Party Suppliers	66,952	60,746
Accrued Taxes	71,238	12,068
Regulatory Liabilities	75,654	61,155
Derivative Liabilities	85,342	91,820
Other Current Liabilities	94,762	98,563
Total Current Liabilities	1,044,910	935,972
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,931,369	1,820,865
Regulatory Liabilities	89,599	74,830
Derivative Liabilities	426,053	336,189
Accrued Pension, SERP and PBOP	274,456	271,056
Other Long-Term Liabilities	130,477	133,446
Total Deferred Credits and Other Liabilities	2,851,954	2,636,386
Capitalization:
Long-Term Debt	2,515,444	2,763,682
Noncontrolling Interest - Preferred Stock of Subsidiaries	116,200	116,200
Common Shareholders' Equity:
Common Shares	60,352	60,352
Capital Surplus, Paid In	2,056,402	1,910,663
Retained Earnings	1,272,962	1,170,278
Accumulated Other Comprehensive Income (Loss)	(165)	(576)
Common Stockholder's Equity	3,389,551	3,140,717
Total Capitalization	6,021,195	6,020,599
Total Liabilities and Capitalization	9,918,059	9,592,957
NSTAR Electric Company [Member]
Current Assets:
Cash and Cash Equivalents	6,154	3,346
Receivables, Net	300,692	229,936
Accounts Receivable from Affiliated Companies	8,891	4,034
Unbilled Revenues	40,370	29,464
Taxes Receivable	0	70,236
Fuel, Materials, Supplies and Inventory	44,827	75,487
Regulatory Assets	259,213	348,408
Prepayments and Other Current Assets	11,025	11,448
Total Current Assets	671,172	772,359
Property, Plant and Equipment, Net	5,875,874	5,655,458
Deferred Debits and Other Assets:
Regulatory Assets	1,043,237	1,112,977
Other Long-Term Assets	118,924	62,467
Total Deferred Debits and Other Assets	1,162,161	1,175,444
Total Assets	7,709,207	7,603,261
Current Liabilities:
Notes Payable	36,000	62,500
Long-Term Debt - Current Portion	0	200,000
Accounts Payable	194,894	228,250
Accounts Payable to Affiliated Companies	64,912	38,648
Obligations to Third Party Suppliers	87,183	56,718
Accrued Taxes	78,429	6,585
Renewable Portfolio Standards Compliance Obligations	56,741	104,847
Regulatory Liabilities	48,842	3,281
Other Current Liabilities	56,879	65,422
Total Current Liabilities	623,880	766,251
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,795,763	1,760,339
Regulatory Liabilities	357,168	264,352
Accrued Pension, SERP and PBOP	91,788	209,153
Other Long-Term Liabilities	125,137	120,939
Total Deferred Credits and Other Liabilities	2,369,856	2,354,783
Capitalization:
Long-Term Debt	2,077,955	1,829,766
Noncontrolling Interest - Preferred Stock of Subsidiaries	43,000	43,000
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	1,020,378	995,378
Retained Earnings	1,573,624	1,613,538
Accumulated Other Comprehensive Income (Loss)	514	545
Common Stockholder's Equity	2,594,516	2,609,461
Total Capitalization	4,715,471	4,482,227
Total Liabilities and Capitalization	7,709,207	7,603,261
Public Service Company Of New Hampshire [Member]
Current Assets:
Cash and Cash Equivalents	4,436	1,733
Receivables, Net	97,613	77,546
Accounts Receivable from Affiliated Companies	4,190	2,352
Unbilled Revenues	39,168	38,207
Taxes Receivable	7,913	43,128
Fuel, Materials, Supplies and Inventory	160,882	156,868
Regulatory Assets	100,598	104,971
Prepayments and Other Current Assets	4,271	24,302
Total Current Assets	419,071	449,107
Property, Plant and Equipment, Net	2,973,057	2,855,363
Deferred Debits and Other Assets:
Regulatory Assets	252,609	257,873
Other Long-Term Assets	35,793	34,176
Total Deferred Debits and Other Assets	288,402	292,049
Total Assets	3,680,530	3,596,519
Current Liabilities:
Notes Payable to Eversource Parent	107,500	231,300
Long-Term Debt - Current Portion	70,000	0
Accounts Payable	76,762	87,925
Accounts Payable to Affiliated Companies	34,350	24,214
Regulatory Liabilities	5,519	6,898
Other Current Liabilities	48,339	43,921
Total Current Liabilities	342,470	394,258
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	774,737	705,894
Regulatory Liabilities	46,428	47,851
Accrued Pension, SERP and PBOP	84,547	89,579
Other Long-Term Liabilities	50,249	50,746
Total Deferred Credits and Other Liabilities	955,961	894,070
Capitalization:
Long-Term Debt	1,001,790	1,071,017
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	843,134	748,634
Retained Earnings	542,530	494,901
Accumulated Other Comprehensive Income (Loss)	(5,355)	(6,361)
Common Stockholder's Equity	1,380,309	1,237,174
Total Capitalization	2,382,099	2,308,191
Total Liabilities and Capitalization	3,680,530	3,596,519
Western Massachusetts Electric Company [Member]
Current Assets:
Cash and Cash Equivalents	0	834
Receivables, Net	59,685	50,912
Accounts Receivable from Affiliated Companies	11,962	18,633
Unbilled Revenues	12,169	15,065
Taxes Receivable	1	33,407
Fuel, Materials, Supplies and Inventory	8,068	5,992
Regulatory Assets	54,081	56,166
Prepayments and Other Current Assets	1,374	1,890
Total Current Assets	147,340	182,899
Property, Plant and Equipment, Net	1,643,335	1,575,306
Deferred Debits and Other Assets:
Regulatory Assets	128,308	135,010
Other Long-Term Assets	28,165	24,875
Total Deferred Debits and Other Assets	156,473	159,885
Total Assets	1,947,148	1,918,090
Current Liabilities:
Notes Payable to Eversource Parent	48,200	143,400
Accounts Payable	38,191	58,364
Accounts Payable to Affiliated Companies	14,501	19,896
Obligations to Third Party Suppliers	11,444	9,654
Renewable Portfolio Standards Compliance Obligations	16,314	6,395
Regulatory Liabilities	12,384	13,122
Other Current Liabilities	12,258	13,878
Total Current Liabilities	153,292	264,709
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	486,137	470,539
Regulatory Liabilities	14,422	11,597
Accrued Pension, SERP and PBOP	16,032	19,515
Other Long-Term Liabilities	42,072	36,819
Total Deferred Credits and Other Liabilities	558,663	538,470
Capitalization:
Long-Term Debt	566,657	517,329
Common Shareholders' Equity:
Common Shares	10,866	10,866
Capital Surplus, Paid In	444,399	391,398
Retained Earnings	215,743	198,140
Accumulated Other Comprehensive Income (Loss)	(2,472)	(2,822)
Common Stockholder's Equity	668,536	597,582
Total Capitalization	1,235,193	1,114,911
Total Liabilities and Capitalization	$ 1,947,148	$ 1,918,090

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Revenues	$ 2,039,706	$ 1,933,105	$ 5,862,525	$ 6,263,597
Operating Expenses:
Purchased Power, Fuel and Transmission	665,810	702,640	2,001,929	2,549,807
Operations and Maintenance	324,734	327,283	965,584	977,306
Depreciation	181,288	167,884	531,781	495,389
Amortization of Regulatory Assets/(Liabilities), Net	43,942	(16,851)	56,223	42,587
Energy Efficiency Programs	149,121	132,107	405,962	380,559
Taxes Other Than Income Taxes	164,942	150,804	479,219	439,221
Total Operating Expenses	1,529,837	1,463,867	4,440,698	4,884,869
Operating Income/(Loss)	509,869	469,238	1,421,827	1,378,728
Interest Expense	99,865	92,534	298,568	279,635
Other Income, Net	13,641	5,241	23,689	23,866
Income Before Income Tax Expense	423,645	381,945	1,146,948	1,122,959
Income Tax Expense	156,446	144,146	428,186	420,640
Net Income	267,199	237,799	718,762	702,319
Net Income Attributable to Noncontrolling Interests	1,880	1,879	5,639	5,639
Net Income Attributable to Common Shareholders	$ 265,319	$ 235,920	$ 713,123	$ 696,680
Basic Earnings Per Common Share (in dollars per share)	$ 0.83	$ 0.74	$ 2.24	$ 2.20
Diluted Earnings Per Common Share (in dollars per share)	0.83	0.74	2.24	2.19
Dividends Declared Per Common Share (in dollars per share)	$ 0.45	$ 0.42	$ 1.34	$ 1.25
Weighted Average Common Shares Outstanding:
Basic (in shares)	317,787,836	317,452,212	317,696,823	317,296,107
Diluted (in shares)	318,577,079	318,405,269	318,511,609	318,396,042
The Connecticut Light And Power Company [Member]
Operating Revenues	$ 760,037	$ 704,262	$ 2,175,141	$ 2,175,733
Operating Expenses:
Purchased Power, Fuel and Transmission	253,509	274,762	760,613	861,562
Operations and Maintenance	123,034	122,280	356,409	358,324
Depreciation	57,675	54,809	172,175	159,903
Amortization of Regulatory Assets/(Liabilities), Net	23,418	(22,859)	30,308	17,917
Energy Efficiency Programs	44,381	42,590	117,969	119,360
Taxes Other Than Income Taxes	81,948	71,563	227,981	201,743
Total Operating Expenses	583,965	543,145	1,665,455	1,718,809
Operating Income/(Loss)	176,072	161,117	509,686	456,924
Interest Expense	36,083	36,716	108,561	109,463
Other Income, Net	3,669	2,356	10,881	8,576
Income Before Income Tax Expense	143,658	126,757	412,006	356,037
Income Tax Expense	57,026	46,569	155,453	127,845
Net Income	86,632	80,188	256,553	228,192
NSTAR Electric Company [Member]
Operating Revenues	780,462	750,724	1,985,979	2,134,728
Operating Expenses:
Purchased Power, Fuel and Transmission	291,382	299,040	764,907	984,035
Operations and Maintenance	96,282	83,486	279,932	228,740
Depreciation	54,695	49,101	159,151	146,818
Amortization of Regulatory Assets/(Liabilities), Net	9,621	2,257	18,275	(10,643)
Energy Efficiency Programs	84,717	67,693	212,882	164,843
Taxes Other Than Income Taxes	35,050	34,982	101,800	95,821
Total Operating Expenses	571,747	536,559	1,536,947	1,609,614
Operating Income/(Loss)	208,715	214,165	449,032	525,114
Interest Expense	21,101	18,992	62,206	57,218
Other Income, Net	5,022	513	7,524	3,649
Income Before Income Tax Expense	192,636	195,686	394,350	471,545
Income Tax Expense	75,440	77,062	154,493	187,397
Net Income	117,196	118,624	239,857	284,148
Public Service Company Of New Hampshire [Member]
Operating Revenues	266,946	234,364	727,753	761,086
Operating Expenses:
Purchased Power, Fuel and Transmission	59,833	53,017	155,700	200,533
Operations and Maintenance	64,183	65,190	187,184	200,085
Depreciation	29,646	26,592	86,524	77,989
Amortization of Regulatory Assets/(Liabilities), Net	14,158	1,967	14,490	29,148
Energy Efficiency Programs	3,983	3,873	10,862	11,001
Taxes Other Than Income Taxes	20,460	20,104	64,543	61,435
Total Operating Expenses	192,263	170,743	519,303	580,191
Operating Income/(Loss)	74,683	63,621	208,450	180,895
Interest Expense	12,397	11,647	37,386	34,582
Other Income, Net	574	685	1,007	2,313
Income Before Income Tax Expense	62,860	52,659	172,071	148,626
Income Tax Expense	24,345	20,158	66,242	56,135
Net Income	38,515	32,501	105,829	92,491
Western Massachusetts Electric Company [Member]
Operating Revenues	124,042	125,093	368,533	403,151
Operating Expenses:
Purchased Power, Fuel and Transmission	32,178	36,465	104,406	149,182
Operations and Maintenance	24,125	21,762	68,018	61,651
Depreciation	11,567	11,196	34,414	32,420
Amortization of Regulatory Assets/(Liabilities), Net	1,102	3,930	3,305	11,194
Energy Efficiency Programs	12,389	12,107	33,593	32,701
Taxes Other Than Income Taxes	10,609	9,599	30,440	28,430
Total Operating Expenses	91,970	95,059	274,176	315,578
Operating Income/(Loss)	32,072	30,034	94,357	87,573
Interest Expense	6,222	5,901	18,298	19,014
Other Income, Net	179	587	133	2,406
Income Before Income Tax Expense	26,029	24,720	76,192	70,965
Income Tax Expense	10,018	9,749	30,089	28,555
Net Income	$ 16,011	$ 14,971	$ 46,103	$ 42,410

CONDENSED CONSOLIDATED STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Income	$ 267,199	$ 237,799	$ 718,762	$ 702,319
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	534	526	1,602	1,544
Changes in Unrealized Gains/(Losses) on Marketable Securities	946	(2,803)	2,271	(3,919)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	(1,733)	764	(2,646)	2,838
Net OCI	(253)	(1,513)	1,227	463
Comprehensive Income Attributable to Noncontrolling Interests	(1,880)	(1,879)	(5,639)	(5,639)
Comprehensive Income Attributable to Common Shareholders	265,066	234,407	714,350	697,143
The Connecticut Light And Power Company [Member]
Net Income	86,632	80,188	256,553	228,192
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	111	111	333	333
Changes in Unrealized Gains/(Losses) on Marketable Securities	33	(98)	78	(137)
Net OCI	144	13	411	196
Comprehensive Income Attributable to Common Shareholders	86,776	80,201	256,964	228,388
NSTAR Electric Company [Member]
Net Income	117,196	118,624	239,857	284,148
Other Comprehensive (Loss)/Income, Net of Tax:
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	(10)	(2)	(31)	(184)
Net OCI	(10)	(2)	(31)	(184)
Comprehensive Income Attributable to Common Shareholders	117,186	118,622	239,826	283,964
Public Service Company Of New Hampshire [Member]
Net Income	38,515	32,501	105,829	92,491
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	290	291	871	872
Changes in Unrealized Gains/(Losses) on Marketable Securities	56	(169)	135	(236)
Net OCI	346	122	1,006	636
Comprehensive Income Attributable to Common Shareholders	38,861	32,623	106,835	93,127
Western Massachusetts Electric Company [Member]
Net Income	16,011	14,971	46,103	42,410
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	109	101	328	270
Changes in Unrealized Gains/(Losses) on Marketable Securities	9	(27)	22	(38)
Net OCI	118	74	350	232
Comprehensive Income Attributable to Common Shareholders	$ 16,129	$ 15,045	$ 46,453	$ 42,642

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities:
Net Income	$ 718,762	$ 702,319
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	531,781	495,389
Deferred Income Taxes	301,413	153,353
Pension, SERP and PBOP Expense	31,627	71,802
Pension and PBOP Contributions	(121,854)	(162,880)
Regulatory Over/(Under) Recoveries, Net	152,808	31,874
Amortization of Regulatory Assets/(Liabilities), Net	56,223	42,587
Other	(27,671)	(39,822)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(191,454)	(148,442)
Fuel, Materials, Supplies and Inventory	25,425	47,380
Taxes Receivable/Accrued, Net	347,898	383,047
Accounts Payable	(121,513)	(233,660)
Other Current Assets and Liabilities, Net	(53,077)	8,370
Net Cash Flows Provided by Operating Activities	1,650,368	1,351,317
Investing Activities:
Investments in Property, Plant and Equipment	(1,359,171)	(1,177,285)
Proceeds from Sales of Marketable Securities	444,209	556,582
Purchases of Marketable Securities	(437,197)	(535,044)
Other Investing Activities	(9,463)	(2,769)
Net Cash Flows Used in Investing Activities	(1,361,622)	(1,158,516)
Financing Activities:
Cash Dividends on Common Shares	(423,471)	(397,363)
Cash Dividends on Preferred Stock	(5,639)	(5,639)
Decrease in Notes Payable	(426,453)	(387,575)
Issuance of Long-Term Debt	800,000	825,000
Retirements of Long-Term Debt	(200,000)	(216,700)
Other Financing Activities	(17,074)	(13,446)
Net Cash Flows Used in Financing Activities	(272,637)	(195,723)
Net Increase/(Decrease) in Cash and Cash Equivalents	16,109	(2,922)
Cash and Cash Equivalents - Beginning of Period	23,947	38,703
Cash and Cash Equivalents - End of Period	40,056	35,781
The Connecticut Light And Power Company [Member]
Operating Activities:
Net Income	256,553	228,192
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	172,175	159,903
Deferred Income Taxes	109,637	(11,011)
Pension and PBOP Contributions, Net of Pension, SERP and PBOP Expense	4,825	10,654
Regulatory Over/(Under) Recoveries, Net	33,492	12,504
Amortization of Regulatory Assets/(Liabilities), Net	30,308	17,917
Other	(14,873)	(13,048)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(100,074)	(91,842)
Taxes Receivable/Accrued, Net	197,422	160,031
Accounts Payable	(30,168)	(20,485)
Other Current Assets and Liabilities, Net	(44,908)	(31,044)
Net Cash Flows Provided by Operating Activities	614,389	421,771
Investing Activities:
Investments in Property, Plant and Equipment	(438,518)	(359,339)
Proceeds from the Sale of Property, Plant and Equipment	9,047	0
Other Investing Activities	310	(740)
Net Cash Flows Used in Investing Activities	(429,161)	(360,079)
Financing Activities:
Cash Dividends on Common Shares	(149,700)	(147,000)
Cash Dividends on Preferred Stock	(4,169)	(4,169)
(Decrease)/Increase in Notes Payable to Eversource Parent	(168,900)	(133,400)
Issuance of Long-Term Debt	0	300,000
Retirements of Long-Term Debt	0	(162,000)
Capital Contributions from Eversource Parent	145,700	105,000
Other Financing Activities	(609)	(9,072)
Net Cash Flows Used in Financing Activities	(177,678)	(50,641)
Net Increase/(Decrease) in Cash and Cash Equivalents	7,550	11,051
Cash and Cash Equivalents - Beginning of Period	1,057	2,356
Cash and Cash Equivalents - End of Period	8,607	13,407
NSTAR Electric Company [Member]
Operating Activities:
Net Income	239,857	284,148
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	159,151	146,818
Deferred Income Taxes	40,960	54,188
Pension and PBOP Contributions, Net of Pension, SERP and PBOP Expense	(25,364)	(1,138)
Regulatory Over/(Under) Recoveries, Net	131,774	(48,903)
Amortization of Regulatory Assets/(Liabilities), Net	18,275	(10,643)
Other	(20,088)	(34,223)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(103,444)	(84,587)
Fuel, Materials, Supplies and Inventory	30,659	21,863
Taxes Receivable/Accrued, Net	141,379	207,516
Accounts Payable	(22,913)	(79,449)
Other Current Assets and Liabilities, Net	(25,942)	46,671
Net Cash Flows Provided by Operating Activities	564,304	502,261
Investing Activities:
Investments in Property, Plant and Equipment	(327,731)	(314,055)
Net Cash Flows Used in Investing Activities	(327,731)	(314,055)
Financing Activities:
Cash Dividends on Common Shares	(278,300)	(148,500)
Cash Dividends on Preferred Stock	(1,470)	(1,470)
Decrease in Notes Payable	(26,500)	(43,500)
Issuance of Long-Term Debt	250,000	0
Retirements of Long-Term Debt	(200,000)	(4,700)
Capital Contributions from Eversource Parent	25,000	0
Other Financing Activities	(2,495)	0
Net Cash Flows Used in Financing Activities	(233,765)	(198,170)
Net Increase/(Decrease) in Cash and Cash Equivalents	2,808	(9,964)
Cash and Cash Equivalents - Beginning of Period	3,346	12,773
Cash and Cash Equivalents - End of Period	6,154	2,809
Public Service Company Of New Hampshire [Member]
Operating Activities:
Net Income	105,829	92,491
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	86,524	77,989
Deferred Income Taxes	74,522	42,563
Regulatory Over/(Under) Recoveries, Net	(4,289)	2,639
Amortization of Regulatory Assets/(Liabilities), Net	14,490	29,148
Other	(12,660)	10,894
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(28,754)	(25,126)
Fuel, Materials, Supplies and Inventory	(4,014)	4,156
Taxes Receivable/Accrued, Net	33,589	9,026
Accounts Payable	14,508	(20,058)
Other Current Assets and Liabilities, Net	26,207	20,141
Net Cash Flows Provided by Operating Activities	305,952	243,863
Investing Activities:
Investments in Property, Plant and Equipment	(215,804)	(209,522)
Other Investing Activities	272	241
Net Cash Flows Used in Investing Activities	(215,532)	(209,281)
Financing Activities:
Cash Dividends on Common Shares	(58,200)	(79,500)
(Decrease)/Increase in Notes Payable to Eversource Parent	(123,800)	46,800
Capital Contributions from Eversource Parent	94,500	0
Other Financing Activities	(217)	(268)
Net Cash Flows Used in Financing Activities	(87,717)	(32,968)
Net Increase/(Decrease) in Cash and Cash Equivalents	2,703	1,614
Cash and Cash Equivalents - Beginning of Period	1,733	489
Cash and Cash Equivalents - End of Period	4,436	2,103
Western Massachusetts Electric Company [Member]
Operating Activities:
Net Income	46,103	42,410
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	34,414	32,420
Deferred Income Taxes	15,587	5,531
Regulatory Over/(Under) Recoveries, Net	323	4,024
Amortization of Regulatory Assets/(Liabilities), Net	3,305	11,194
Other	(2,532)	(4,500)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	1,933	(32,664)
Taxes Receivable/Accrued, Net	36,658	24,064
Accounts Payable	(16,240)	(14,018)
Other Current Assets and Liabilities, Net	5,277	(463)
Net Cash Flows Provided by Operating Activities	124,828	67,998
Investing Activities:
Investments in Property, Plant and Equipment	(104,811)	(93,705)
Proceeds from Sales of Marketable Securities	1,934	71,110
Purchases of Marketable Securities	(1,894)	(71,625)
Net Cash Flows Used in Investing Activities	(104,771)	(94,220)
Financing Activities:
Cash Dividends on Common Shares	(28,500)	(27,900)
(Decrease)/Increase in Notes Payable to Eversource Parent	(95,200)	104,800
Issuance/(Retirement) of Long-Term Debt	50,000	(50,000)
Capital Contributions from Eversource Parent	53,000	0
Other Financing Activities	(191)	(20)
Net Cash Flows Used in Financing Activities	(20,891)	26,880
Net Increase/(Decrease) in Cash and Cash Equivalents	(834)	658
Cash and Cash Equivalents - Beginning of Period	834	0
Cash and Cash Equivalents - End of Period	$ 0	$ 658

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES A. Basis of Presentation Eversource Energy is a public utility holding company primarily engaged, through its wholly owned regulated utility subsidiaries, in the energy delivery business. Eversource Energy’s wholly owned regulated utility subsidiaries consist of CL&P, NSTAR Electric, PSNH, WMECO, Yankee Gas and NSTAR Gas. Eversource provides energy delivery service to approximately 3.6 million electric and natural gas customers through these six regulated utilities in Connecticut, Massachusetts and New Hampshire. The unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH include the accounts of each of their respective subsidiaries. Intercompany transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH and the unaudited condensed financial statements of CL&P and WMECO are herein collectively referred to as the “financial statements.” The combined notes to the financial statements have been prepared pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures included in annual financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. The accompanying financial statements should be read in conjunction with the Combined Notes to Financial Statements included in Item 8, “Financial Statements and Supplementary Data,” of the Eversource 2015 Form 10-K, which was filed with the SEC. The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The financial statements contain, in the opinion of management, all adjustments (including normal, recurring adjustments) necessary to present fairly Eversource’s, CL&P’s, NSTAR Electric’s, PSNH’s and WMECO’s financial position as of September 30, 2016 and December 31, 2015 , the results of operations and comprehensive income for the three and nine months ended September 30, 2016 and 2015 , and the cash flows for the nine months ended September 30, 2016 and 2015 . The results of operations and comprehensive income for the three and nine months ended September 30, 2016 and 2015 and the cash flows for the nine months ended September 30, 2016 and 2015 are not necessarily indicative of the results expected for a full year. Eversource consolidates CYAPC and YAEC because CL&P’s, NSTAR Electric’s, PSNH’s and WMECO’s combined ownership interest in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and WMECO and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements. Access Northeast is a natural gas pipeline and storage project (the Project) being developed jointly by Eversource, Spectra Energy Partners, LP (Spectra), and National Grid plc (National Grid) through Algonquin Gas Transmission, LLC (AGT). The Project will enhance the Algonquin and Maritimes & Northeast pipeline systems using existing routes and will include two new LNG storage tanks and liquefaction and vaporization facilities in Acushnet, Massachusetts that will be connected to the Algonquin natural gas pipeline. Eversource and Spectra each own a 40 percent interest in the Project, with the remaining 20 percent interest owned by National Grid. The total projected cost for both the pipeline and the LNG storage facilities will be funded in proportion to the respective ownership interest. Eversource’s cumulative equity investment in the Project as of September 30, 2016 of $28.6 million is presented in Other Long-Term Assets. Eversource’s utility subsidiaries’ distribution (including generation) and transmission businesses are subject to rate-regulation that is based on cost recovery and meets the criteria for application of accounting guidance for entities with rate-regulated operations, which considers the effect of regulation on the differences in the timing of the recognition of certain revenues and expenses from those of other businesses and industries. See Note 2, “Regulatory Accounting,” for further information. Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation and as a result of the adoption of new accounting guidance. See Note 1B, “Summary of Significant Accounting Policies – Accounting Standards,” for further information. B. Accounting Standards Accounting Standards Issued but not Yet Effective: In May 2014, the Financial Accounting Standards Board (FASB) issued an Accounting Standards Update (ASU) 2014-9, Revenue from Contracts with Customers , which amends existing revenue recognition guidance and is required to be applied retrospectively (either to each reporting period presented or cumulatively at the date of initial application). In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers – Deferral of the Effective Date , which defers the effective date of ASU 2014-9 to the first quarter of 2018, with 2017 application permitted. The guidance continues to be interpreted on an industry specific level. The Company is evaluating the requirements and potential impacts of ASU 2014-9 and will implement the standard in the first quarter of 2018. The ASU is not currently expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric, PSNH or WMECO. In January 2016, the FASB issued ASU 2016-1, Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Liabilities , which is required to be implemented in the first quarter of 2018. The Company is reviewing the requirements of the ASU. The ASU will remove the available-for-sale designation for equity securities, whereby changes in fair value are recorded in accumulated other comprehensive income within shareholders’ equity, and will require changes in fair value of all equity securities to be recorded in earnings beginning on January 1, 2018, with the unrealized gain or loss on available-for-sale equity securities as of that date reclassified to retained earnings as a cumulative effect of adoption. The fair value of available-for-sale equity securities subject to this guidance as of September 30, 2016 was approximately $50 million . The remaining available-for-sale equity securities included in marketable securities on the balance sheet are held in nuclear decommissioning trusts and are subject to regulatory accounting treatment and will not be impacted by this guidance. Implementation of the ASU for other financial instruments is not expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric, PSNH or WMECO. In February 2016, the FASB issued ASU 2016-2, Leases , which changes existing lease accounting guidance and is required to be applied in the first quarter of 2019, with earlier application permitted. The ASU is required to be implemented for leases beginning on the date of initial application. For prior periods presented, leases are required to be recognized and measured using a modified retrospective approach. The Company is reviewing the requirements of ASU 2016-2, including balance sheet recognition of leases previously deemed operating leases, and expects to implement the ASU in the first quarter of 2019. Recently Adopted Accounting Standards: In March 2016, the FASB issued ASU 2016-9, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting . The ASU is intended to simplify some aspects of the accounting for share-based payment transactions. The Company implemented this guidance in the first quarter of 2016, as permitted by early adoption. Beginning in the first quarter of 2016, the excess tax benefits associated with the distribution of stock compensation awards, previously recognized in Capital Surplus, Paid In within Common Shareholders’ Equity on the balance sheet, are recognized in income tax expense in the income statement. The implementation reduced income tax expense by $2.9 million for the nine months ended September 30, 2016 . Also, beginning in 2016, in the statement of cash flows, the excess tax benefits are presented as an operating activity rather than a financing activity, and in both periods presented, cash paid to satisfy the statutory income tax withholding obligation previously reflected within operating activities in 2015 is now treated as a financing activity. The cash payments to satisfy this obligation for the nine months ended September 30, 2016 and 2015 were $9.1 million and $9.7 million , respectively, and are included in Other Financing Activities on the statements of cash flows. C. Provision for Uncollectible Accounts Eversource, including CL&P, NSTAR Electric, PSNH and WMECO, presents its receivables at estimated net realizable value by maintaining a provision for uncollectible accounts. This provision is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. The estimate is based upon historical collection and write-off experience and management’s assessment of collectability from customers. Management continuously assesses the collectability of receivables and adjusts collectability estimates based on actual experience. Receivable balances are written off against the provision for uncollectible accounts when the customer accounts are terminated and these balances are deemed to be uncollectible. The PURA allows CL&P and Yankee Gas to accelerate the recovery of accounts receivable balances attributable to qualified customers under financial or medical duress (uncollectible hardship accounts receivable) outstanding for greater than 180 days and 90 days, respectively. The DPU allows WMECO and NSTAR Gas to also recover in rates amounts associated with certain uncollectible hardship accounts receivable. Certain of NSTAR Electric’s uncollectible hardship accounts receivable are expected to be recovered in future rates, similar to WMECO and NSTAR Gas. These uncollectible customer account balances are included in Regulatory Assets or Other Long-Term Assets on the balance sheets. The total provisions for uncollectible accounts and for uncollectible hardship accounts, which is included in the total provision, are included in Receivables, Net on the balance sheets, and were as follows: Total Provision for Uncollectible Accounts Uncollectible Hardship (Millions of Dollars) As of September 30, 2016 As of December 31, 2015 As of September 30, 2016 As of December 31, 2015 Eversource $ 208.1 $ 190.7 $ 126.5 $ 118.5 CL&P 85.3 79.5 66.9 68.1 NSTAR Electric 59.9 52.6 30.3 25.3 PSNH 9.9 8.7 — — WMECO 16.8 14.0 10.7 7.4 D. Fair Value Measurements Fair value measurement guidance is applied to derivative contracts that are not elected or designated as “normal purchases or normal sales” (normal) and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill and AROs, and the estimated fair value of preferred stock and long-term debt. Fair Value Hierarchy: In measuring fair value, Eversource uses observable market data when available in order to minimize the use of unobservable inputs. Inputs used in fair value measurements are categorized into three fair value hierarchy levels for disclosure purposes. The entire fair value measurement is categorized based on the lowest level of input that is significant to the fair value measurement. Eversource evaluates the classification of assets and liabilities measured at fair value on a quarterly basis, and Eversource’s policy is to recognize transfers between levels of the fair value hierarchy as of the end of the reporting period. The three levels of the fair value hierarchy are described below: Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 - Inputs are quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs are observable. Level 3 - Quoted market prices are not available. Fair value is derived from valuation techniques in which one or more significant inputs or assumptions are unobservable. Where possible, valuation techniques incorporate observable market inputs that can be validated to external sources such as industry exchanges, including prices of energy and energy-related products. Determination of Fair Value: The valuation techniques and inputs used in Eversource’s fair value measurements are described in Note 4, “Derivative Instruments,” Note 5, “Marketable Securities,” and Note 10, “Fair Value of Financial Instruments,” to the financial statements. E. Other Income, Net Items included within Other Income, Net on the statements of income primarily consist of investment income/(loss), interest income, AFUDC related to equity funds, and equity in earnings of equity method investees. Investment income/(loss) primarily relates to debt and equity securities held in trust. For further information, see Note 5, “Marketable Securities,” to the financial statements. F. Other Taxes Gross receipts taxes levied by the state of Connecticut are collected by CL&P and Yankee Gas from their respective customers. These gross receipts taxes are shown separately with collections in Operating Revenues and with payments in Taxes Other Than Income Taxes on the statements of income as follows: For the Three Months Ended For the Nine Months Ended (Millions of Dollars) September 30, 2016 September 30, 2015 September 30, 2016 September 30, 2015 Eversource $ 45.1 $ 37.8 $ 124.8 $ 112.9 CL&P 42.6 35.5 112.2 98.0 As agents for state and local governments, Eversource’s companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income. G. Supplemental Cash Flow Information Non-cash investing activities include plant additions included in Accounts Payable as follows: (Millions of Dollars) As of September 30, 2016 As of September 30, 2015 Eversource $ 203.6 $ 160.7 CL&P 64.5 46.0 NSTAR Electric 39.4 31.2 PSNH 31.0 33.8 WMECO 17.6 15.5

REGULATORY ACCOUNTING

REGULATORY ACCOUNTING	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
REGULATORY ACCOUNTING	REGULATORY ACCOUNTING Eversource’s Regulated companies are subject to rate-regulation that is based on cost recovery and meets the criteria for application of accounting guidance for rate-regulated operations, which considers the effect of regulation on the timing of the recognition of certain revenues and expenses. The Regulated companies’ financial statements reflect the effects of the rate-making process. The rates charged to the customers of Eversource’s Regulated companies are designed to collect each company’s costs to provide service, including a return on investment. Management believes it is probable that each of the Regulated companies will recover their respective investments in long-lived assets, including regulatory assets. If management were to determine that it could no longer apply the accounting guidance applicable to rate-regulated enterprises to any of the Regulated companies’ operations, or if management could not conclude it is probable that costs would be recovered from customers in future rates, the costs would be charged to net income in the period in which the determination is made. Regulatory Assets: The components of regulatory assets were as follows: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Eversource Eversource Benefit Costs $ 1,618.7 $ 1,828.2 Derivative Liabilities 443.7 388.0 Income Taxes, Net 641.7 650.9 Storm Restoration Costs 407.7 436.9 Goodwill-related 469.5 484.9 Regulatory Tracker Mechanisms 454.1 526.5 Contractual Obligations - Yankee Companies 66.0 134.4 Other Regulatory Assets 120.9 134.0 Total Regulatory Assets 4,222.3 4,583.8 Less: Current Portion 752.4 845.8 Total Long-Term Regulatory Assets $ 3,469.9 $ 3,738.0 As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH WMECO Benefit Costs $ 407.1 $ 414.6 $ 174.7 $ 82.1 $ 413.6 $ 479.9 $ 164.2 $ 84.9 Derivative Liabilities 441.0 2.7 — — 380.8 1.3 — — Income Taxes, Net 438.5 88.3 27.0 31.2 444.4 85.7 34.5 31.8 Storm Restoration Costs 253.7 115.1 20.8 18.1 271.4 110.9 31.5 23.1 Goodwill-related — 403.1 — — — 416.3 — — Regulatory Tracker Mechanisms 50.6 230.4 99.9 37.8 45.1 311.0 101.2 40.1 Other Regulatory Assets 75.4 48.2 30.8 13.2 82.0 56.3 31.5 11.3 Total Regulatory Assets 1,666.3 1,302.4 353.2 182.4 1,637.3 1,461.4 362.9 191.2 Less: Current Portion 267.7 259.2 100.6 54.1 268.3 348.4 105.0 56.2 Total Long-Term Regulatory Assets $ 1,398.6 $ 1,043.2 $ 252.6 $ 128.3 $ 1,369.0 $ 1,113.0 $ 257.9 $ 135.0 Regulatory Costs in Other Long-Term Assets: The Regulated companies had $87.9 million (including $4.0 million for CL&P, $40.2 million for NSTAR Electric, $6.1 million for PSNH and $20.1 million for WMECO) and $75.3 million (including $3.1 million for CL&P, $35.4 million for NSTAR Electric, $4.8 million for PSNH, and $16.7 million for WMECO) of additional regulatory costs as of September 30, 2016 and December 31, 2015 , respectively, that were included in Other Long-Term Assets on the balance sheets. These amounts represent incurred costs for which recovery has not yet been specifically approved by the applicable regulatory agency. However, based on regulatory policies or past precedent on similar costs, management believes it is probable that these costs will ultimately be approved and recovered from customers in rates. Regulatory Liabilities: The components of regulatory liabilities were as follows: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Eversource Eversource Cost of Removal $ 457.7 $ 437.1 Regulatory Tracker Mechanisms 153.4 99.7 AFUDC - Transmission 65.8 66.1 Other Regulatory Liabilities 33.7 18.5 Total Regulatory Liabilities 710.6 621.4 Less: Current Portion 160.4 107.8 Total Long-Term Regulatory Liabilities $ 550.2 $ 513.6 As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH WMECO Cost of Removal $ 39.7 $ 269.5 $ 45.8 $ 5.8 $ 24.1 $ 257.4 $ 47.2 $ 2.8 Benefit Costs — 81.7 — — — — — — Regulatory Tracker Mechanisms 62.2 48.4 2.6 12.2 56.2 3.3 3.4 12.9 AFUDC - Transmission 50.6 6.4 — 8.8 51.5 5.7 — 8.9 Other Regulatory Liabilities 12.8 — 3.5 — 4.2 1.3 4.2 0.1 Total Regulatory Liabilities 165.3 406.0 51.9 26.8 136.0 267.7 54.8 24.7 Less: Current Portion 75.7 48.8 5.5 12.4 61.2 3.3 6.9 13.1 Total Long-Term Regulatory Liabilities $ 89.6 $ 357.2 $ 46.4 $ 14.4 $ 74.8 $ 264.4 $ 47.9 $ 11.6

PROPERTY, PLANT AND EQUIPMENT A

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION	PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION The following tables summarize the investments in utility property, plant and equipment by asset category: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Eversource Eversource Distribution - Electric $ 13,536.1 $ 13,054.8 Distribution - Natural Gas 2,865.8 2,727.2 Transmission - Electric 8,033.0 7,691.9 Generation 1,218.9 1,194.1 Electric and Natural Gas Utility 25,653.8 24,668.0 Other (1) 635.3 558.6 Property, Plant and Equipment, Gross 26,289.1 25,226.6 Less: Accumulated Depreciation Electric and Natural Gas Utility (6,442.3 ) (6,141.1 ) Other (285.8 ) (255.6 ) Total Accumulated Depreciation (6,728.1 ) (6,396.7 ) Property, Plant and Equipment, Net 19,561.0 18,829.9 Construction Work in Progress 1,246.9 1,062.5 Total Property, Plant and Equipment, Net $ 20,807.9 $ 19,892.4 (1) These assets are primarily comprised of building improvements, computer software, hardware and equipment at Eversource Service. As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH WMECO Distribution $ 5,513.9 $ 5,309.2 $ 1,918.3 $ 834.6 $ 5,377.2 $ 5,100.5 $ 1,804.8 $ 812.3 Transmission 3,752.7 2,211.7 1,005.5 1,014.9 3,618.0 2,131.3 928.2 964.9 Generation — — 1,182.9 36.0 — — 1,158.1 36.0 Property, Plant and Equipment, Gross 9,266.6 7,520.9 4,106.7 1,885.5 8,995.2 7,231.8 3,891.1 1,813.2 Less: Accumulated Depreciation (2,102.3 ) (1,996.8 ) (1,243.8 ) (330.6 ) (2,041.9 ) (1,886.8 ) (1,171.0 ) (307.0 ) Property, Plant and Equipment, Net 7,164.3 5,524.1 2,862.9 1,554.9 6,953.3 5,345.0 2,720.1 1,506.2 Construction Work in Progress 288.9 351.8 110.2 88.4 203.5 310.5 135.3 69.1 Total Property, Plant and Equipment, Net $ 7,453.2 $ 5,875.9 $ 2,973.1 $ 1,643.3 $ 7,156.8 $ 5,655.5 $ 2,855.4 $ 1,575.3

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS	DERIVATIVE INSTRUMENTS The Regulated companies purchase and procure energy and energy-related products, which are subject to price volatility, for their customers. The costs associated with supplying energy to customers are recoverable from customers in future rates. The Regulated companies manage the risks associated with the price volatility of energy and energy-related products through the use of derivative and nonderivative contracts. Many of the derivative contracts meet the definition of, and are designated as, normal and qualify for accrual accounting under the applicable accounting guidance. The costs and benefits of derivative contracts that meet the definition of normal are recognized in Operating Expenses or Operating Revenues on the statements of income, as applicable, as electricity or natural gas is delivered. Derivative contracts that are not designated as normal are recorded at fair value as current or long-term Derivative Assets or Derivative Liabilities on the balance sheets. For the Regulated companies, regulatory assets or regulatory liabilities are recorded to offset the fair values of derivatives, as contract settlement amounts are recovered from, or refunded to, customers in their respective energy supply rates. The gross fair values of derivative assets and liabilities with the same counterparty are offset and reported as net Derivative Assets or Derivative Liabilities, with current and long-term portions, on the balance sheets. The following table presents the gross fair values of contracts, categorized by risk type, and the net amounts recorded as current or long-term derivative assets or liabilities: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Commodity Supply and Price Risk Management Netting (1) Net Amount Recorded as a Derivative Commodity Supply and Price Risk Netting (1) Net Amount Recorded as a Derivative Current Derivative Assets: Level 2: Eversource $ 2.6 $ (0.2 ) $ 2.4 $ — $ — $ — Level 3: Eversource 15.7 (10.4 ) 5.3 16.7 (10.9 ) 5.8 CL&P 15.3 (10.4 ) 4.9 16.7 (10.9 ) 5.8 NSTAR Electric 0.4 — 0.4 — — — Long-Term Derivative Assets: Level 2: Eversource $ — $ — $ — $ 0.1 $ — $ 0.1 Level 3: Eversource 79.3 (13.8 ) 65.5 62.0 (19.3 ) 42.7 CL&P 79.3 (13.8 ) 65.5 60.7 (19.3 ) 41.4 NSTAR Electric — — — 1.3 — 1.3 Current Derivative Liabilities: Level 2: Eversource $ — $ — $ — $ (5.8 ) $ — $ (5.8 ) Level 3: Eversource (87.1 ) — (87.1 ) (92.3 ) — (92.3 ) CL&P (85.3 ) — (85.3 ) (91.8 ) — (91.8 ) NSTAR Electric (1.8 ) — (1.8 ) (0.5 ) — (0.5 ) Long-Term Derivative Liabilities: Level 3: Eversource $ (427.4 ) $ — $ (427.4 ) $ (337.1 ) $ — $ (337.1 ) CL&P (426.1 ) — (426.1 ) (336.2 ) — (336.2 ) NSTAR Electric (1.3 ) — (1.3 ) (0.9 ) — (0.9 ) (1) Amounts represent derivative assets and liabilities that Eversource elected to record net on the balance sheets. These amounts are subject to master netting agreements or similar agreements for which the right of offset exists. For further information on the fair value of derivative contracts, see Note 1D, “Summary of Significant Accounting Policies - Fair Value Measurements,” to the financial statements. Derivative Contracts at Fair Value with Offsetting Regulatory Amounts Commodity Supply and Price Risk Management : As required by regulation, CL&P, along with UI, has capacity-related contracts with generation facilities. CL&P has a sharing agreement with UI, with 80 percent of the costs or benefits of each contract borne by or allocated to CL&P and 20 percent borne by or allocated to UI. The combined capacity of these contracts is 787 MW. The capacity contracts extend through 2026 and obligate both CL&P and UI to make or receive payments on a monthly basis to or from the generation facilities based on the difference between a set capacity price and the capacity market price received in the ISO-NE capacity markets. In addition, CL&P has a contract to purchase 0.1 million MWh of energy per year through 2020. NSTAR Electric has a renewable energy contract to purchase 0.1 million MWh of energy per year through 2018 and a capacity-related contract to purchase up to 35 MW per year through 2019. As of September 30, 2016 and December 31, 2015 , Eversource had NYMEX financial contracts for natural gas futures in order to reduce variability associated with the purchase price of approximately 10.2 million and 9.1 million MMBtu of natural gas, respectively. For the three months ended September 30, 2016 and 2015 , there were losses of $53.4 million and $8.8 million , respectively, deferred as regulatory costs, which reflect the change in fair value associated with Eversource’s derivative contracts. For the nine months ended September 30, 2016 and 2015 , these losses were $127.8 million and $58.9 million , respectively. Fair Value Measurements of Derivative Instruments Derivative contracts classified as Level 2 in the fair value hierarchy relate to the financial contracts for natural gas futures. Prices are obtained from broker quotes and are based on actual market activity. The contracts are valued using NYMEX natural gas prices. Valuations of these contracts also incorporate discount rates using the yield curve approach. The fair value of derivative contracts classified as Level 3 utilizes significant unobservable inputs. The fair value is modeled using income techniques, such as discounted cash flow valuations adjusted for assumptions relating to exit price. Significant observable inputs for valuations of these contracts include energy and energy-related product prices in future years for which quoted prices in an active market exist. Fair value measurements categorized in Level 3 of the fair value hierarchy are prepared by individuals with expertise in valuation techniques, pricing of energy and energy-related products, and accounting requirements. The future power and capacity prices for periods that are not quoted in an active market or established at auction are based on available market data and are escalated based on estimates of inflation in order to address the full time period of the contract. Valuations of derivative contracts using a discounted cash flow methodology include assumptions regarding the timing and likelihood of scheduled payments and also reflect non-performance risk, including credit, using the default probability approach based on the counterparty’s credit rating for assets and the Company’s credit rating for liabilities. Valuations incorporate estimates of premiums or discounts that would be required by a market participant to arrive at an exit price, using historical market transactions adjusted for the terms of the contract. The following is a summary of Eversource’s, including CL&P’s and NSTAR Electric’s, Level 3 derivative contracts and the range of the significant unobservable inputs utilized in the valuations over the duration of the contracts: As of September 30, 2016 As of December 31, 2015 Range Period Covered Range Period Covered Capacity Prices: Eversource $ 5.50 — 9.75 per kW-Month 2020 - 2026 $ 10.81 — 15.82 per kW-Month 2016 - 2026 CL&P $ 5.50 — 9.75 per kW-Month 2020 - 2026 $ 10.81 — 12.60 per kW-Month 2019 - 2026 Forward Reserve: Eversource, CL&P $ 1.40 — 2.00 per kW-Month 2016 - 2024 $2.00 per kW-Month 2016 - 2024 REC Prices: Eversource, NSTAR Electric $ 29 — 37 per REC 2016 - 2018 $ 45 — 51 per REC 2016 - 2018 Exit price premiums of 4 percent through 21 percent are also applied on these contracts and reflect the uncertainty and liquidity premiums that would be required based on the most recent market activity available for similar type contracts. Significant increases or decreases in future energy or capacity prices in isolation would decrease or increase, respectively, the fair value of the derivative liability. Any increases in risk premiums would increase the fair value of the derivative liability. Changes in these fair values are recorded as a regulatory asset or liability and do not impact net income. Valuations using significant unobservable inputs: The following table presents changes in the Level 3 category of derivative assets and derivative liabilities measured at fair value on a recurring basis. The derivative assets and liabilities are presented on a net basis. For the Three Months Ended September 30, 2016 2015 (Millions of Dollars) Eversource CL&P NSTAR Electric Eversource CL&P NSTAR Derivatives, Net: Fair Value as of Beginning of Period $ (412.6 ) $ (411.3 ) $ (1.3 ) $ (422.4 ) $ (420.2 ) $ (2.2 ) Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets and Liabilities (52.3 ) (49.8 ) (2.5 ) (6.0 ) (7.6 ) 1.6 Settlements 21.2 20.1 1.1 21.4 20.9 0.5 Fair Value as of End of Period $ (443.7 ) $ (441.0 ) $ (2.7 ) $ (407.0 ) $ (406.9 ) $ (0.1 ) For the Nine Months Ended September 30, 2016 2015 (Millions of Dollars) Eversource CL&P NSTAR Eversource CL&P NSTAR Derivatives, Net: Fair Value as of Beginning of Period $ (380.9 ) $ (380.8 ) $ (0.1 ) $ (415.4 ) $ (410.9 ) $ (4.5 ) Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets and Liabilities (128.9 ) (122.0 ) (6.9 ) (55.3 ) (56.6 ) 1.3 Settlements 66.1 61.8 4.3 63.7 60.6 3.1 Fair Value as of End of Period $ (443.7 ) $ (441.0 ) $ (2.7 ) $ (407.0 ) $ (406.9 ) $ (0.1 )

MARKETABLE SECURITIES

MARKETABLE SECURITIES	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]	5. MARKETABLE SECURITIES Eversource maintains trusts that hold marketable securities to fund certain non-qualified executive benefits. These trusts are not subject to regulatory oversight by state or federal agencies. CYAPC and YAEC maintain legally restricted trusts, each of which holds marketable securities, to fund the decommissioning and spent nuclear fuel removal obligations of their nuclear fuel storage facilities. Trading Securities: Eversource has elected to record certain equity securities as trading securities, with the changes in fair values recorded in Other Income, Net on the statements of income. As of September 30, 2016 and December 31, 2015 , these securities were classified as Level 1 in the fair value hierarchy and totaled $10.3 million and $14.2 million , respectively. For the three months ended September 30, 2016 and 2015 , net gains on these securities of $0.1 million and net losses of $0.5 million , respectively, and for the nine months ended September 30, 2016 and 2015 , net gains of $0.6 million and $1.6 million , respectively, were recorded in Other Income, Net on the statements of income. Dividend income is recorded in Other Income, Net when dividends are declared. Available-for-Sale Securities: The following is a summary of available-for-sale securities, which are recorded at fair value and are included in current and long-term Marketable Securities on the balance sheets. As of September 30, 2016 As of December 31, 2015 Eversource (Millions of Dollars) Amortized Cost Pre-Tax Unrealized Gains Pre-Tax Unrealized Losses Fair Value Amortized Cost Pre-Tax Unrealized Gains Pre-Tax Unrealized Losses Fair Value Debt Securities $ 261.2 $ 10.7 $ — $ 271.9 $ 256.5 $ 4.5 $ (0.6 ) $ 260.4 Equity Securities 206.7 63.7 (1.0 ) 269.4 215.3 59.2 (3.4 ) 271.1 Eversource’s debt and equity securities include CYAPC’s and YAEC’s marketable securities held in nuclear decommissioning trusts of $446.9 million and $436.9 million as of September 30, 2016 and December 31, 2015 , respectively. Unrealized gains and losses for these nuclear decommissioning trusts are recorded in Marketable Securities with the corresponding offset to Other Long-Term Liabilities on the balance sheets, with no impact on the statements of income. Unrealized Losses and Other-than-Temporary Impairment: There have been no significant unrealized losses, other-than-temporary impairments or credit losses for the three and nine months ended September 30, 2016 and 2015 . Factors considered in determining whether a credit loss exists include the duration and severity of the impairment, adverse conditions specifically affecting the issuer, and the payment history, ratings and rating changes of the security. For asset-backed debt securities, underlying collateral and expected future cash flows are also evaluated. Realized Gains and Losses: Realized gains and losses on available-for-sale securities are recorded in Other Income, Net for Eversource’s benefit trust and are offset in Other Long-Term Liabilities for CYAPC and YAEC. Eversource utilizes the specific identification basis method for the Eversource benefit trust, and the average cost basis method for the CYAPC and YAEC nuclear decommissioning trusts to compute the realized gains and losses on the sale of available-for-sale securities. Contractual Maturities : As of September 30, 2016 , the contractual maturities of available-for-sale debt securities were as follows: Eversource (Millions of Dollars) Amortized Cost Fair Value Less than one year (1) $ 29.3 $ 29.1 One to five years 58.0 59.1 Six to ten years 47.0 49.5 Greater than ten years 126.9 134.2 Total Debt Securities $ 261.2 $ 271.9 (1) Amounts in the Less than one year category include securities in the CYAPC and YAEC nuclear decommissioning trusts, which are restricted and are classified in long-term Marketable Securities on the balance sheets. Fair Value Measurements: The following table presents the marketable securities recorded at fair value on a recurring basis by the level in which they are classified within the fair value hierarchy: Eversource (Millions of Dollars) As of September 30, 2016 As of December 31, 2015 Level 1: Mutual Funds and Equities $ 279.7 $ 285.3 Money Market Funds 24.5 26.9 Total Level 1 $ 304.2 $ 312.2 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 65.5 $ 46.6 Corporate Debt Securities 43.3 43.9 Asset-Backed Debt Securities 18.0 20.0 Municipal Bonds 110.3 111.4 Other Fixed Income Securities 10.3 11.6 Total Level 2 $ 247.4 $ 233.5 Total Marketable Securities $ 551.6 $ 545.7 U.S. government issued debt securities are valued using market approaches that incorporate transactions for the same or similar bonds and adjustments for yields and maturity dates. Corporate debt securities are valued using a market approach, utilizing recent trades of the same or similar instrument and also incorporating yield curves, credit spreads and specific bond terms and conditions. Asset-backed debt securities include collateralized mortgage obligations, commercial mortgage backed securities, and securities collateralized by auto loans, credit card loans or receivables. Asset-backed debt securities are valued using recent trades of similar instruments, prepayment assumptions, yield curves, issuance and maturity dates, and tranche information. Municipal bonds are valued using a market approach that incorporates reported trades and benchmark yields. Other fixed income securities are valued using pricing models, quoted prices of securities with similar characteristics, and discounted cash flows.
MARKETABLE SECURITIES	Fair Value Measurements Fair value measurement guidance is applied to derivative contracts that are not elected or designated as “normal purchases or normal sales” (normal) and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill and AROs, and the estimated fair value of preferred stock and long-term debt. Fair Value Hierarchy: In measuring fair value, Eversource uses observable market data when available in order to minimize the use of unobservable inputs. Inputs used in fair value measurements are categorized into three fair value hierarchy levels for disclosure purposes. The entire fair value measurement is categorized based on the lowest level of input that is significant to the fair value measurement. Eversource evaluates the classification of assets and liabilities measured at fair value on a quarterly basis, and Eversource’s policy is to recognize transfers between levels of the fair value hierarchy as of the end of the reporting period. The three levels of the fair value hierarchy are described below: Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 - Inputs are quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs are observable. Level 3 - Quoted market prices are not available. Fair value is derived from valuation techniques in which one or more significant inputs or assumptions are unobservable. Where possible, valuation techniques incorporate observable market inputs that can be validated to external sources such as industry exchanges, including prices of energy and energy-related products.

SHORT-TERM AND LONG-TERM DEBT

SHORT-TERM AND LONG-TERM DEBT	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
SHORT-TERM AND LONG-TERM DEBT	SHORT-TERM AND LONG-TERM DEBT Commercial Paper Programs and Credit Agreements : Eversource parent has a $1.45 billion commercial paper program allowing Eversource parent to issue commercial paper as a form of short-term debt. As of September 30, 2016 and December 31, 2015 , Eversource parent had $698.5 million and approximately $1.1 billion , respectively, in short-term borrowings outstanding under the Eversource parent commercial paper program, leaving $751.5 million and $351.5 million of available borrowing capacity as of September 30, 2016 and December 31, 2015 , respectively. The weighted-average interest rate on these borrowings as of September 30, 2016 and December 31, 2015 was 0.66 percent and 0.72 percent , respectively. As of September 30, 2016 , there were intercompany loans from Eversource parent of $108.5 million to CL&P, $107.5 million to PSNH, and $48.2 million to WMECO. As of December 31, 2015 , there were intercompany loans from Eversource parent of $277.4 million to CL&P, $231.3 million to PSNH and $143.4 million to WMECO. Eversource parent, CL&P, PSNH, WMECO, NSTAR Gas and Yankee Gas are parties to a five -year $1.45 billion revolving credit facility. Effective September 26, 2016, the revolving credit facility’s termination date was extended for one additional year to September 4, 2021. The revolving credit facility serves to backstop Eversource parent’s $1.45 billion commercial paper program. There were no borrowings outstanding on the revolving credit facility as of September 30, 2016 or December 31, 2015. NSTAR Electric has a $450 million commercial paper program allowing NSTAR Electric to issue commercial paper as a form of short-term debt. As of September 30, 2016 and December 31, 2015 , NSTAR Electric had $36.0 million and $62.5 million , respectively, in short-term borrowings outstanding under its commercial paper program, leaving $414.0 million and $387.5 million of available borrowing capacity as of September 30, 2016 and December 31, 2015 , respectively. The weighted-average interest rate on these borrowings as of September 30, 2016 and December 31, 2015 was 0.42 percent and 0.40 percent , respectively. NSTAR Electric is a party to a five -year $450 million revolving credit facility. Effective September 26, 2016, the revolving credit facility’s termination date was extended for one additional year to September 4, 2021. The revolving credit facility serves to backstop NSTAR Electric’s $450 million commercial paper program. There were no borrowings outstanding on the revolving credit facility as of September 30, 2016 or December 31, 2015. Amounts outstanding under the commercial paper programs are included in Notes Payable for Eversource and NSTAR Electric and are classified in current liabilities on the balance sheets as all borrowings are outstanding for no more than 364 days at one time. Intercompany loans from Eversource parent to CL&P, PSNH and WMECO are included in Notes Payable to Eversource Parent and are classified in current liabilities on their respective balance sheets. Intercompany loans from Eversource parent to CL&P, PSNH and WMECO are eliminated in consolidation on Eversource’s balance sheets. Short-Term Borrowing Limits: The amount of short-term borrowings that may be incurred by NSTAR Electric is subject to periodic approval by the FERC. On August 8, 2016, the FERC granted authorization to allow NSTAR Electric to issue total short-term debt securities in an aggregate principal amount not to exceed $655 million outstanding at any one time, through October 23, 2018. Long-Term Debt Issuances: In March 2016, Eversource parent issued $250 million of 2.50 percent Series I Senior Notes due to mature in 2021 and $250 million of 3.35 percent Series J Senior Notes due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings under the Eversource parent commercial paper program. In May 2016, NSTAR Electric issued $250 million of 2.70 percent debentures, due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings under the NSTAR Electric commercial paper program and fund capital expenditures and working capital. In June 2016, WMECO issued $50 million of 2.75 percent Series H Senior Notes, due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings. Long-Term Debt Repayments: In May 2016, NSTAR Electric repaid at maturity $200 million variable rate debentures, using short-term borrowings.

PENSION BENEFITS AND POSTRETIRE

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSIONS	9 Months Ended
	Sep. 30, 2016
Postemployment Benefits [Abstract]
PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSIONS	PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSIONS Eversource Service sponsors a defined benefit retirement plan (Pension Plan) that covers eligible employees, including, among others, employees of CL&P, NSTAR Electric, PSNH and WMECO. In addition to the Pension Plan, Eversource maintains non-qualified defined benefit retirement plans sponsored by Eversource Service (SERP Plans), which provide benefits in excess of Internal Revenue Code limitations to eligible participants consisting of current and retired employees. Eversource Service also sponsors defined benefit postretirement plans that provide certain benefits, primarily medical, dental and life insurance, to retired employees that met certain age and service eligibility requirements, including, among others, employees of CL&P, NSTAR Electric, PSNH and WMECO (PBOP Plan). Effective January 1, 2016, the Company refined its method of estimating the discount rate for the service and interest cost components of Pension and PBOP expense from the yield-curve approach to the spot rate methodology, which provides a more precise measurement by matching projected cash flows to the corresponding spot rates on the yield curve. Historically, these components were estimated using the same weighted-average discount rate as for the funded status. The discount rates used to estimate the 2016 service cost were 4.89 percent and 4.09 percent for the Pension and PBOP plans, respectively. The discount rates used to estimate the 2016 interest cost were 3.80 percent and 2.88 percent for the Pension and PBOP plans, respectively. The total pre-tax benefit of this change on Pension and PBOP expense, prior to the capitalized portion and amounts deferred and recovered through rate reconciliation mechanisms, for the three months ended September 30, 2016 was $11.5 million and $2.5 million for the Pension and PBOP plans, respectively, and $35 million and $7.5 million for the nine months ended September 30, 2016 , respectively. In August 2016, the Company amended its PBOP Plan, which standardized separate benefit structures that existed within the plan and made other benefit changes. The amendment required a remeasurement of the benefit obligation using current assumptions, including updated discount rates and asset values. The discount rate used to remeasure the benefit obligation was 3.62 percent . The remeasurement resulted in a reduction to the benefit liability of approximately $244 million , offset by an increase to the unamortized actuarial losses of approximately $142 million driven primarily by the decrease in the discount rate. Overall, the impact of the remeasurement reduced the PBOP plan’s accumulated projected benefit obligation and regulatory assets by approximately $102 million and $106 million , respectively, and increased accumulated other comprehensive losses by $4.0 million . The remeasurement resulted in a decrease in the net periodic benefit costs for PBOP benefits, prior to the capitalized portion and amounts deferred and recovered through rate reconciliation mechanisms, of approximately $10 million , which will be recorded in the period August 1, 2016 through December 31, 2016, and most of this amount will be deferred for future refund to customers. The components of net periodic benefit expense for the Pension, SERP and PBOP Plans are shown below. The net periodic benefit expense and the intercompany allocations, less the capitalized portions of pension, SERP and PBOP amounts, are included in Operations and Maintenance expense on the statements of income. Capitalized pension and PBOP amounts relate to employees working on capital projects and are included in Property, Plant and Equipment, Net on the balance sheets. Pension, SERP and PBOP expense reflected in the statements of cash flows for CL&P, NSTAR Electric, PSNH and WMECO does not include the intercompany allocations or the corresponding capitalized portion, as these amounts are cash settled on a short-term basis. Pension and SERP Eversource For the Three Months Ended For the Nine Months Ended (Millions of Dollars) September 30, 2016 September 30, 2015 (1) September 30, 2016 September 30, 2015 (1) Service Cost $ 18.6 $ 22.7 $ 56.6 $ 68.7 Interest Cost 46.4 56.9 139.2 170.3 Expected Return on Plan Assets (79.4 ) (83.9 ) (238.5 ) (252.1 ) Actuarial Loss 31.4 36.5 94.2 111.9 Prior Service Cost 0.9 0.9 2.6 2.7 Total Net Periodic Benefit Expense $ 17.9 $ 33.1 $ 54.1 $ 101.5 Capitalized Pension Expense $ 5.4 $ 9.8 $ 16.8 $ 31.3 PBOP Eversource For the Three Months Ended For the Nine Months Ended (Millions of Dollars) September 30, 2016 September 30, 2015 (1) September 30, 2016 September 30, 2015 (1) Service Cost $ 3.0 $ 4.1 $ 9.2 $ 10.3 Interest Cost 7.5 11.8 26.5 30.4 Expected Return on Plan Assets (15.9 ) (16.9 ) (47.3 ) (43.2 ) Actuarial Loss 3.0 1.7 5.0 4.5 Prior Service Credit (3.6 ) (0.1 ) (3.7 ) (0.3 ) Total Net Periodic Benefit Expense/(Income) $ (6.0 ) $ 0.6 $ (10.3 ) $ 1.7 Capitalized PBOP Expense/(Income) $ (2.6 ) $ — $ (4.6 ) $ 0.1 Pension and SERP For the Three Months Ended September 30, 2016 For the Three Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 4.6 $ 3.3 $ 2.5 $ 0.8 $ 6.2 $ 3.7 $ 3.1 $ 1.0 Interest Cost 10.2 8.5 5.1 2.1 12.9 10.0 6.1 2.6 Expected Return on Plan Assets (18.0 ) (16.9 ) (9.6 ) (4.4 ) (19.8 ) (17.5 ) (10.1 ) (4.7 ) Actuarial Loss 6.3 8.7 2.5 1.3 8.0 8.7 2.9 1.6 Prior Service Cost 0.4 — 0.1 0.1 0.4 — 0.1 0.1 Total Net Periodic Benefit Expense/(Income) $ 3.5 $ 3.6 $ 0.6 $ (0.1 ) $ 7.7 $ 4.9 $ 2.1 $ 0.6 Intercompany Allocations $ 3.5 $ 2.2 $ 1.0 $ 0.6 $ 5.8 $ 3.4 $ 1.6 $ 1.1 Capitalized Pension Expense $ 2.2 $ 2.0 $ 0.4 $ 0.1 $ 4.7 $ 2.7 $ 0.8 $ 0.5 Pension and SERP For the Nine Months Ended September 30, 2016 For the Nine Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 14.3 $ 9.9 $ 7.5 $ 2.4 $ 18.4 $ 11.2 $ 9.0 $ 3.2 Interest Cost 31.2 25.3 15.4 6.3 38.4 30.2 18.1 7.8 Expected Return on Plan Assets (54.2 ) (50.7 ) (28.9 ) (13.1 ) (59.1 ) (52.5 ) (30.3 ) (14.2 ) Actuarial Loss 19.2 25.8 7.5 4.1 24.2 27.0 8.8 4.8 Prior Service Cost 1.1 — 0.3 0.2 1.1 0.1 0.4 0.2 Total Net Periodic Benefit Expense/(Income) $ 11.6 $ 10.3 $ 1.8 $ (0.1 ) $ 23.0 $ 16.0 $ 6.0 $ 1.8 Intercompany Allocations $ 10.3 $ 6.7 $ 3.0 $ 1.9 $ 18.0 $ 10.3 $ 5.0 $ 3.3 Capitalized Pension Expense $ 7.1 $ 5.7 $ 1.0 $ 0.3 $ 14.1 $ 8.6 $ 2.6 $ 1.4 PBOP For the Three Months Ended September 30, 2016 For the Three Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 0.6 $ 0.6 $ 0.4 $ 0.1 $ 0.5 $ 1.3 $ 0.3 $ 0.1 Interest Cost 1.3 2.5 0.7 0.3 1.8 4.8 1.0 0.3 Expected Return on Plan Assets (2.5 ) (6.4 ) (1.4 ) (0.6 ) (2.8 ) (6.8 ) (1.5 ) (0.6 ) Actuarial Loss 0.5 1.2 0.2 — 0.2 0.6 0.1 — Prior Service Cost/(Credit) 0.2 (2.9 ) 0.1 — — (0.1 ) — — Total Net Periodic Benefit Expense/(Income) $ 0.1 $ (5.0 ) $ — $ (0.2 ) $ (0.3 ) $ (0.2 ) $ (0.1 ) $ (0.2 ) Intercompany Allocations $ — $ (0.1 ) $ — $ — $ 0.4 $ 0.2 $ 0.1 $ 0.1 Capitalized PBOP Expense/(Income) $ — $ (2.2 ) $ — $ (0.1 ) $ (0.1 ) $ — $ 0.1 $ — PBOP For the Nine Months Ended September 30, 2016 For the Nine Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 1.4 $ 2.5 $ 0.9 $ 0.3 $ 1.6 $ 4.0 $ 1.0 $ 0.3 Interest Cost 4.0 10.3 2.2 0.8 5.4 14.2 2.9 1.1 Expected Return on Plan Assets (7.6 ) (19.2 ) (4.2 ) (1.7 ) (8.3 ) (20.5 ) (4.4 ) (1.9 ) Actuarial Loss 0.9 1.7 0.5 — 0.5 1.8 0.4 — Prior Service Cost/(Credit) 0.2 (2.9 ) 0.1 — — (0.1 ) — — Total Net Periodic Benefit Income $ (1.1 ) $ (7.6 ) $ (0.5 ) $ (0.6 ) $ (0.8 ) $ (0.6 ) $ (0.1 ) $ (0.5 ) Intercompany Allocations $ 0.3 $ — $ — $ — $ 1.4 $ 0.7 $ 0.3 $ 0.3 Capitalized PBOP Expense/(Income) $ (0.5 ) $ (3.3 ) $ — $ (0.3 ) $ (0.2 ) $ (0.1 ) $ 0.2 $ (0.1 ) (1) Amounts excluded approximately $0.8 million and $2.4 million for the three and nine months ended September 30, 2015 , respectively, that represented amounts included in other deferred debits.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES A. Environmental Matters Eversource, CL&P, NSTAR Electric, PSNH and WMECO are subject to environmental laws and regulations intended to mitigate or remove the effect of past operations and improve or maintain the quality of the environment. These laws and regulations require the removal or the remedy of the effect on the environment of the disposal or release of certain specified hazardous substances at current and former operating sites. Eversource, CL&P, NSTAR Electric, PSNH and WMECO have an active environmental auditing and training program and each believes it is substantially in compliance with all enacted laws and regulations. The number of environmental sites and related reserves for which remediation or long-term monitoring, preliminary site work or site assessment is being performed are as follows: As of September 30, 2016 As of December 31, 2015 Number of Sites Reserve (in millions) Number of Sites Reserve (in millions) Eversource 63 $ 59.7 64 $ 51.1 CL&P 14 4.7 14 4.6 NSTAR Electric 14 2.3 15 2.4 PSNH 12 4.3 12 4.5 WMECO 4 0.7 4 0.6 Included in the Eversource number of sites and reserve amounts above are former MGP sites that were operated several decades ago and manufactured gas from coal and other processes, which resulted in certain by-products remaining in the environment that may pose a potential risk to human health and the environment, for which Eversource may have potential liability. The reserve balances related to these former MGP sites were $53.9 million and $45.5 million as of September 30, 2016 and December 31, 2015 , respectively, and related primarily to the natural gas business segment. These reserve estimates are subjective in nature as they take into consideration several different remediation options at each specific site. The reliability and precision of these estimates can be affected by several factors, including new information concerning either the level of contamination at the site, the extent of Eversource’s, CL&P’s, NSTAR Electric’s, PSNH’s, and WMECO’s responsibility for remediation or the extent of remediation required, recently enacted laws and regulations, or changes in cost estimates due to certain economic factors. It is possible that new information or future developments could require a reassessment of the potential exposure to related environmental matters. As this information becomes available, management will continue to assess the potential exposure and adjust the reserves accordingly. B. Guarantees and Indemnifications In the normal course of business, Eversource parent provides credit assurances on behalf of its subsidiaries, including CL&P, NSTAR Electric, PSNH and WMECO, in the form of guarantees. Eversource parent issued a declining balance guaranty on behalf of Eversource Gas Transmission LLC, a wholly-owned subsidiary, to guarantee the payment of the subsidiary’s capital contributions for its investment in the Access Northeast project. The guaranty will not exceed $206 million and decreases as capital contributions are made. The guaranty will expire upon the earlier of the full performance of the guaranteed obligations or December 31, 2021. Eversource parent issued a guaranty on behalf of its subsidiary, NPT, under which, beginning at the time the Northern Pass Transmission line goes into commercial operation, Eversource parent will guarantee the financial obligations of NPT under the TSA with HQ in an amount not to exceed $25 million . Eversource parent’s obligations under the guaranty expire upon the full, final and indefeasible payment of the guaranteed obligations. Eversource parent has also entered into a guaranty on behalf of NPT under which Eversource parent will guarantee NPT’s obligations under its letter of credit facility with a financial institution pursuant to which NPT may request letters of credit in an aggregate amount of up to approximately $14 million . Eversource parent has also guaranteed certain indemnification and other obligations as a result of the sales of former unregulated subsidiaries and the termination of an unregulated business, with maximum exposures either not specified or not material. Management does not anticipate a material impact to Net Income as a result of these various guarantees and indemnifications. The following table summarizes Eversource parent’s exposure to guarantees and indemnifications of its subsidiaries to external parties, as of September 30, 2016 : Company Description Maximum Exposure (in millions) Expiration Dates On behalf of subsidiaries: Eversource Gas Transmission LLC Access Northeast Project Capital Contributions Guaranty $ 186.5 2021 Various Surety Bonds (1) $ 37.1 2016 - 2018 Eversource Service and Rocky River Realty Company Lease Payments for Vehicles and Real Estate $ 9.8 2019 - 2024 (1) Surety bond expiration dates reflect termination dates, the majority of which will be renewed or extended. Certain surety bonds contain credit ratings triggers that would require Eversource parent to post collateral in the event that the unsecured debt credit ratings of Eversource parent are downgraded. C. Spent Nuclear Fuel Litigation - Yankee Companies The Yankee Companies have filed separate complaints against the DOE in the Court of Federal Claims seeking monetary damages resulting from the DOE’s failure to provide for a permanent facility to store spent nuclear fuel pursuant to the terms of the 1983 spent fuel and high level waste disposal contracts between the Yankee Companies and the DOE. The court had previously awarded the Yankee Companies damages for Phase I and Phase II of litigation resulting from the DOE’s failure to meet its contractual obligations. Phase I covered damages incurred in the years 1998 through 2002 and Phase II covered damages incurred in the years 2001 through 2008 for CYAPC and YAEC and from 2002 through 2008 for MYAPC. DOE Phase III Damages - In August 2013, the Yankee Companies each filed subsequent lawsuits against the DOE seeking recovery of actual damages incurred in the years 2009 through 2012. The DOE Phase III trial concluded on July 1, 2015, followed by a post-trial briefing that concluded on October 14, 2015. On March 25, 2016, the court issued its decision and awarded CYAPC, YAEC and MYAPC damages of $32.6 million , $19.6 million and $24.6 million , respectively. In total, the Yankee Companies were awarded $76.8 million of the $77.9 million in damages sought in Phase III. The decision became final on July 18, 2016, and the Yankee Companies received the awards from the DOE on October 14, 2016. The Yankee Companies have filed a request with FERC seeking approval of the proposed distribution of certain amounts of the awarded damages proceeds to member companies, including CL&P, NSTAR Electric, PSNH, and WMECO. Subject to receipt of FERC approval, CYAPC and MYAPC expect to be able to make distributions in December 2016. MYAPC also anticipates refunding approximately $57 million from its spent nuclear fuel trust, a portion of which will be refunded to the Eversource utility subsidiaries. In total, Eversource expects to receive approximately $26 million , of which CL&P expects to receive $13.6 million , NSTAR Electric expects to receive $5 million , PSNH expects to receive $3.9 million , and WMECO expects to receive $3.6 million . These anticipated amounts will be refunded to the customers of the respective Eversource utility subsidiaries. D. FERC ROE Complaints Four separate complaints have been filed at FERC by combinations of New England state attorneys general, state regulatory commissions, consumer advocates, consumer groups, municipal parties and other parties (collectively the “Complainants”). In the first three complaints, the Complainants challenged the NETOs’ base ROE of 11.14 percent that had been utilized since 2006 and sought an order to reduce it prospectively from the date of the final FERC order and for the 15 -month complaint refund periods stipulated in the separate complaints. The FERC ordered a 10.57 percent base ROE for the first complaint refund period and prospectively from October 16, 2014, and that a utility’s total or maximum ROE for any incentive project shall not exceed the top of the new zone of reasonableness, which was set at 11.74 percent . In late 2014, the NETOs made a compliance filing, and CL&P, NSTAR Electric, PSNH and WMECO have refunded all amounts associated with the first complaint period. The NETOs and Complainants have appealed the decision in the first complaint to the D.C. Circuit Court of Appeals. A court decision is expected in late 2016 or early 2017. The Company has recorded reserves across the complaint periods at its electric subsidiaries. In the first nine months of 2015, the Company recognized a pre-tax charge to earnings (excluding interest) of $20 million , of which $12.5 million was recorded at CL&P, $2.4 million at NSTAR Electric, $1 million at PSNH, and $4.1 million at WMECO. The pre-tax charge was recorded as a regulatory liability and as a reduction to Operating Revenues. For the second and third complaints, the state parties, municipal utilities and FERC trial staff each believe that the base ROE should be reduced to an amount lower than 11.14 percent . FERC’s determination to set these cases for hearing was appealed to the D.C. Circuit Court of Appeals, and is being held in abeyance pending a final FERC order. On March 22, 2016, the FERC ALJ issued an initial decision on the second and third complaints. For the second complaint period, the FERC ALJ recommended a zone of reasonableness of 7.12 percent to 10.42 percent and a base ROE of 9.59 percent . For the third complaint period, the FERC ALJ recommended a zone of reasonableness of 7.04 percent to 12.19 percent and a base ROE of 10.90 percent . The FERC ALJ also affirmed that the maximum ROE for transmission incentive projects should be the top of the zone of reasonableness. The NETOs filed briefs on April 21, 2016, in which the NETOs identified corrections and requested changes that should be made to the FERC ALJ’s recommendations. A final FERC order is expected in late 2016 or early 2017. The Company believes that the range of potential loss for the second complaint period (the 15 -month period beginning December 27, 2012) is from a base ROE of 10.57 percent to a base ROE of 9.59 percent . As the FERC ALJ initial decision on the third complaint recommended a base ROE of 10.90 percent , the Company concluded there is currently no range of potential loss for that complaint period (the 15 -month period beginning July 31, 2014). Given the differences between the recommended base ROEs in the FERC ALJ’s initial decision on the second and third complaints, as well as other factors, the Company is unable to predict the outcome of the final FERC order on these two complaints. The Company does not believe any base ROE outcome within the 10.57 percent to 9.59 percent range is more likely than the base ROEs used to record the current revenues and reserves, and therefore the Company believes that the current reserves for the second complaint period are appropriate at this time. The impact of a 10 basis point change to the existing base ROE of 10.57 percent would affect Eversource’s after-tax earnings by approximately $3 million for each of the 15 -month second and third complaint periods. If the Company adjusted its reserves based on the recommendations in the FERC ALJ initial decision (for both the base ROE and maximum ROE for transmission incentive projects) for the second and third complaints, then it would result in an after-tax increase of approximately $34 million and an after-tax decrease of approximately $8 million , respectively, to the existing reserves. For the fourth complaint, filed April 29, 2016, certain municipal utilities claimed the current base ROE of 10.57 percent and the incentive cap of 11.74 percent are unjust and unreasonable. The NETOs answered on June 3, 2016 and requested that FERC dismiss the complaint. On September 20, 2016, the FERC issued an order establishing hearing and settlement judge procedures and set a 15 -month complaint period beginning April 29, 2016. Management cannot at this time predict the ultimate outcome of this proceeding or the estimated impacts on the financial position, results of operations or cash flows of Eversource, CL&P, NSTAR Electric, PSNH and WMECO. A FERC ALJ initial decision could be received in 2017. E. Eversource and NSTAR Electric Boston Harbor Civil Action On July 15, 2016, the United States Army Corps of Engineers filed a civil action in the United States District Court for the District of Massachusetts under provisions of the Rivers and Harbors Act of 1899 and the Clean Water Act against NSTAR Electric, Harbor Electric Energy Company, a wholly-owned subsidiary of NSTAR Electric (“HEEC”), and the Massachusetts Water Resources Authority (together with NSTAR Electric and HEEC, the “Defendants”). The action alleges that the Defendants failed to comply with certain permitting requirements relating to the placement of the HEEC-owned electric distribution cable beneath Boston Harbor. The action seeks an order to force HEEC to comply with cable depth requirements in the U.S. Army Corps of Engineers’ permit or alternatively to remove the electric distribution cable and cease unauthorized work in U.S. waterways. The action also seeks civil penalties and other costs. Management believes there are valid defenses to the claims and intends to defend NSTAR Electric and HEEC vigorously. Concurrently, NSTAR Electric and HEEC are seeking to work collaboratively with all parties for a mutually beneficial resolution. At this time, management is unable to predict the outcome of this action or the impact on Eversource’s and NSTAR Electric’s financial position, results of operations, or cash flows.

PSNH GENERATION ASSET SALE

PSNH GENERATION ASSET SALE	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
PSNH GENERATION ASSET SALE	PSNH GENERATION ASSET SALE On June 10, 2015, Eversource and PSNH entered into the 2015 Public Service Company of New Hampshire Restructuring and Rate Stabilization Agreement (the Agreement) with the New Hampshire Office of Energy and Planning, certain members of the NHPUC staff, the Office of Consumer Advocate, two State Senators, and several other parties. Under the terms of the Agreement, PSNH agreed to divest its generation assets, subject to NHPUC approval. The Agreement provided for a resolution of issues pertaining to PSNH’s generation assets in pending regulatory proceedings before the NHPUC. The Agreement provided for the Clean Air Project prudence proceeding to be resolved and all remaining Clean Air Project costs to be included in rates effective January 1, 2016. In addition, PSNH will not seek a general distribution rate increase effective before July 1, 2017 and will contribute $5 million to create a clean energy fund, which will not be recoverable from its customers. In the first nine months of 2015, PSNH recorded the $5 million contribution as a long-term liability and an increase to Operations and Maintenance expense on the statements of income. On July 1, 2016, the NHPUC approved the Agreement in an order that, among other things, instructs PSNH to begin the process to divest its generation assets. The NHPUC selected an auction adviser to assist with the divestiture, and a final plan and auction process will be determined by the NHPUC in the fourth quarter of 2016. Upon completion of the divestiture process, all remaining stranded costs will be recovered via bonds that will be secured by a non-bypassable charge or through recoveries in rates billed to PSNH’s customers. If the NHPUC approves the sale of the assets, the Company expects the assets will be sold prior to the end of 2017. The sales price of the generating assets could be less than the carrying value, but the Company believes that full recovery of PSNH’s generation assets is probable through a combination of cash flows during the remaining operating period, sales proceeds upon divestiture, and recovery of stranded costs in future rates. As of September 30, 2016, PSNH’s generation assets were as follows: (Millions of Dollars) Gross Plant $ 1,191.0 Accumulated Depreciation (552.1 ) Net Plant 638.9 Fuel, Materials, Supplies and Allowances 161.9

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS The following methods and assumptions were used to estimate the fair value of each of the following financial instruments: Preferred Stock and Long-Term Debt: The fair value of CL&P’s and NSTAR Electric’s preferred stock is based upon pricing models that incorporate interest rates and other market factors, valuations or trades of similar securities and cash flow projections. The fair value of long-term debt securities is based upon pricing models that incorporate quoted market prices for those issues or similar issues adjusted for market conditions, credit ratings of the respective companies and treasury benchmark yields. The fair values provided in the tables below are classified as Level 2 within the fair value hierarchy. Carrying amounts and estimated fair values are as follows: As of September 30, 2016 As of December 31, 2015 Eversource (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 166.6 $ 155.6 $ 157.9 Long-Term Debt 9,609.0 10,454.8 9,034.5 9,425.9 CL&P NSTAR Electric PSNH WMECO (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value As of September 30, 2016: Preferred Stock Not Subject to Mandatory Redemption $ 116.2 $ 122.2 $ 43.0 $ 44.4 $ — $ — $ — $ — Long-Term Debt 2,765.4 3,216.8 2,078.0 2,338.8 1,071.8 1,142.9 566.7 616.9 As of December 31, 2015: Preferred Stock Not Subject to Mandatory Redemption $ 116.2 $ 114.9 $ 43.0 $ 43.0 $ — $ — $ — $ — Long-Term Debt 2,763.7 3,031.6 2,029.8 2,182.4 1,071.0 1,121.2 517.3 551.8 Derivative Instruments and Marketable Securities: Derivative instruments and investments in marketable securities are carried at fair value. For further information, see Note 4, “Derivative Instruments,” and Note 5, “Marketable Securities,” to the financial statements. See Note 1D, “Summary of Significant Accounting Policies - Fair Value Measurements,” for the fair value measurement policy and the fair value hierarchy.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) The changes in accumulated other comprehensive income/(loss) by component, net of tax, is as follows: For the Nine Months Ended September 30, 2016 For the Nine Months Ended September 30, 2015 Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Eversource (Millions of Dollars) Balance as of Beginning of Period $ (10.3 ) $ (1.9 ) $ (54.6 ) $ (66.8 ) $ (12.4 ) $ 0.7 $ (62.3 ) $ (74.0 ) OCI Before Reclassifications — 2.3 (5.3 ) (3.0 ) — (3.9 ) (0.4 ) (4.3 ) Amounts Reclassified from AOCI 1.6 — 2.6 4.2 1.5 — 3.3 4.8 Net OCI 1.6 2.3 (2.7 ) 1.2 1.5 (3.9 ) 2.9 0.5 Balance as of End of Period $ (8.7 ) $ 0.4 $ (57.3 ) $ (65.6 ) $ (10.9 ) $ (3.2 ) $ (59.4 ) $ (73.5 ) Eversource’s qualified cash flow hedging instruments represent interest rate swap agreements on debt issuances that were settled in prior years. The settlement amount was recorded in AOCI and is being amortized into Net Income over the term of the underlying debt instrument. CL&P, PSNH and WMECO continue to amortize interest rate swaps settled in prior years from AOCI into Interest Expense over the remaining life of the associated long-term debt. Such interest rate swaps are not material to their respective financial statements. Defined benefit plan OCI amounts before reclassifications relate to actuarial gains and losses and prior service costs that arose during the year and were recognized in AOCI. For further information see Note 7, “Pension Benefits and Postretirement Benefits Other Than Pensions.” The unamortized actuarial gains and losses and prior service costs on the defined benefit plans are amortized from AOCI into Operations and Maintenance expense over the average future employee service period, and are reflected in amounts reclassified from AOCI.

COMMON SHARES

COMMON SHARES	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
COMMON SHARES	COMMON SHARES The following table sets forth the Eversource parent common shares and the shares of common stock of CL&P, NSTAR Electric, PSNH and WMECO that were authorized and issued as well as the respective per share par values: Shares Authorized as of September 30, 2016 and Issued as of Par Value December 31, 2015 September 30, 2016 December 31, 2015 Eversource $ 5 380,000,000 333,878,402 333,862,615 CL&P $ 10 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 100 100 PSNH $ 1 100,000,000 301 301 WMECO $ 25 1,072,471 434,653 434,653 As of both September 30, 2016 and December 31, 2015 , there were 16,671,366 Eversource common shares held as treasury shares. As of September 30, 2016 and December 31, 2015 , Eversource common shares outstanding were 317,207,036 and 317,191,249 , respectively. COMMON SHAREHOLDERS’ EQUITY AND NONCONTROLLING INTERESTS Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for the three months ended September 30, 2016 and 2015 , and $5.6 million for the nine months ended September 30, 2016 and 2015 . These dividends were presented as Net Income Attributable to Noncontrolling Interests on the Eversource statements of income. Noncontrolling Interest – Preferred Stock of Subsidiaries on the Eversource balance sheets totaled $155.6 million as of September 30, 2016 and December 31, 2015 . On the Eversource balance sheets, Common Shareholders’ Equity was fully attributable to the parent and Noncontrolling Interest – Preferred Stock of Subsidiaries was fully attributable to the noncontrolling interest.

COMMON SHAREHOLDERS' EQUITY AND

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS	COMMON SHARES The following table sets forth the Eversource parent common shares and the shares of common stock of CL&P, NSTAR Electric, PSNH and WMECO that were authorized and issued as well as the respective per share par values: Shares Authorized as of September 30, 2016 and Issued as of Par Value December 31, 2015 September 30, 2016 December 31, 2015 Eversource $ 5 380,000,000 333,878,402 333,862,615 CL&P $ 10 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 100 100 PSNH $ 1 100,000,000 301 301 WMECO $ 25 1,072,471 434,653 434,653 As of both September 30, 2016 and December 31, 2015 , there were 16,671,366 Eversource common shares held as treasury shares. As of September 30, 2016 and December 31, 2015 , Eversource common shares outstanding were 317,207,036 and 317,191,249 , respectively. COMMON SHAREHOLDERS’ EQUITY AND NONCONTROLLING INTERESTS Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for the three months ended September 30, 2016 and 2015 , and $5.6 million for the nine months ended September 30, 2016 and 2015 . These dividends were presented as Net Income Attributable to Noncontrolling Interests on the Eversource statements of income. Noncontrolling Interest – Preferred Stock of Subsidiaries on the Eversource balance sheets totaled $155.6 million as of September 30, 2016 and December 31, 2015 . On the Eversource balance sheets, Common Shareholders’ Equity was fully attributable to the parent and Noncontrolling Interest – Preferred Stock of Subsidiaries was fully attributable to the noncontrolling interest.

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic EPS is computed based upon the weighted average number of common shares outstanding during each period. Diluted EPS is computed on the basis of the weighted average number of common shares outstanding plus the potential dilutive effect of certain share-based compensation awards as if they were converted into common shares. The dilutive effect of unvested RSU and performance share awards and unexercised stock options is calculated using the treasury stock method. RSU and performance share awards are included in basic weighted average common shares outstanding as of the date that all necessary vesting conditions have been satisfied. For the three and nine months ended September 30, 2016 and 2015 , there were no antidilutive share awards excluded from the computation. The following table sets forth the components of basic and diluted EPS: Eversource (Millions of Dollars, except share information) For the Three Months Ended For the Nine Months Ended September 30, 2016 September 30, 2015 September 30, 2016 September 30, 2015 Net Income Attributable to Common Shareholders $ 265.3 $ 235.9 $ 713.1 $ 696.7 Weighted Average Common Shares Outstanding: Basic 317,787,836 317,452,212 317,696,823 317,296,107 Dilutive Effect 789,243 953,057 814,786 1,099,935 Diluted 318,577,079 318,405,269 318,511,609 318,396,042 Basic EPS $ 0.83 $ 0.74 $ 2.24 $ 2.20 Diluted EPS $ 0.83 $ 0.74 $ 2.24 $ 2.19

SEGMENT INFORMATION

SEGMENT INFORMATION	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION Presentation: Eversource is organized into the Electric Distribution, Electric Transmission and Natural Gas Distribution reportable segments and Other based on a combination of factors, including the characteristics of each segments’ services, the sources of operating revenues and expenses and the regulatory environment in which each segment operates. These reportable segments represent substantially all of Eversource’s total consolidated revenues. Revenues from the sale of electricity and natural gas primarily are derived from residential, commercial and industrial customers and are not dependent on any single customer. The Electric Distribution reportable segment includes the generation activities of PSNH and WMECO. The remainder of Eversource’s operations is presented as Other in the tables below and primarily consists of 1) the equity in earnings of Eversource parent from its subsidiaries and intercompany interest income, both of which are eliminated in consolidation, and interest expense related to the debt of Eversource parent, 2) the revenues and expenses of Eversource Service, most of which are eliminated in consolidation, 3) the operations of CYAPC and YAEC, 4) the results of Eversource Gas Transmission LLC and 5) the results of other unregulated subsidiaries, which are not part of its core business. Cash flows used for investments in plant included in the segment information below are cash capital expenditures that do not include amounts incurred but not paid, cost of removal, AFUDC related to equity funds, and the capitalized portions of pension expense. Eversource’s reportable segments are determined based upon the level at which Eversource’s chief operating decision maker assesses performance and makes decisions about the allocation of company resources. Each of Eversource’s subsidiaries, including CL&P, NSTAR Electric, PSNH and WMECO, has one reportable segment. Eversource’s operating segments and reporting units are consistent with its reportable business segments. Eversource’s segment information is as follows: For the Three Months Ended September 30, 2016 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 1,623.4 $ 99.2 $ 306.8 $ 211.5 $ (201.2 ) $ 2,039.7 Depreciation and Amortization (154.8 ) (15.2 ) (47.1 ) (8.6 ) 0.5 (225.2 ) Other Operating Expenses (1,146.8 ) (87.8 ) (90.2 ) (179.3 ) 199.5 (1,304.6 ) Operating Income/(Loss) 321.8 (3.8 ) 169.5 23.6 (1.2 ) 509.9 Interest Expense (49.0 ) (10.2 ) (26.9 ) (15.1 ) 1.3 (99.9 ) Other Income, Net 5.3 0.6 6.3 256.9 (255.5 ) 13.6 Net Income Attributable to Common Shareholders $ 170.1 $ (7.0 ) $ 88.4 $ 268.5 $ (254.7 ) $ 265.3 For the Nine Months Ended September 30, 2016 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 4,362.6 $ 622.3 $ 892.5 $ 636.8 $ (651.7 ) $ 5,862.5 Depreciation and Amortization (380.9 ) (47.9 ) (137.7 ) (23.1 ) 1.6 (588.0 ) Other Operating Expenses (3,230.1 ) (462.4 ) (245.7 ) (564.7 ) 650.2 (3,852.7 ) Operating Income 751.6 112.0 509.1 49.0 0.1 1,421.8 Interest Expense (144.6 ) (30.8 ) (82.2 ) (45.8 ) 4.8 (298.6 ) Other Income, Net 11.6 0.5 14.2 781.4 (784.0 ) 23.7 Net Income Attributable to Common Shareholders $ 381.3 $ 51.9 $ 266.6 $ 791.7 $ (778.4 ) $ 713.1 Cash Flows Used for Investments in Plant $ 570.9 $ 170.3 $ 536.2 $ 81.8 $ — $ 1,359.2 For the Three Months Ended September 30, 2015 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 1,543.7 $ 106.2 $ 270.4 $ 211.6 $ (198.8 ) $ 1,933.1 Depreciation and Amortization (84.5 ) (17.5 ) (42.4 ) (7.1 ) 0.5 (151.0 ) Other Operating Expenses (1,140.8 ) (92.7 ) (78.3 ) (199.6 ) 198.5 (1,312.9 ) Operating Income/(Loss) 318.4 (4.0 ) 149.7 4.9 0.2 469.2 Interest Expense (47.4 ) (9.2 ) (25.9 ) (11.2 ) 1.2 (92.5 ) Other Income/(Loss), Net 1.9 (0.2 ) 3.8 241.9 (242.2 ) 5.2 Net Income Attributable to Common Shareholders $ 167.5 $ (3.7 ) $ 78.0 $ 234.9 $ (240.8 ) $ 235.9 For the Nine Months Ended September 30, 2015 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 4,686.5 $ 799.6 $ 787.2 $ 655.2 $ (664.9 ) $ 6,263.6 Depreciation and Amortization (342.1 ) (53.4 ) (122.6 ) (21.5 ) 1.6 (538.0 ) Other Operating Expenses (3,535.7 ) (631.5 ) (225.5 ) (619.4 ) 665.2 (4,346.9 ) Operating Income 808.7 114.7 439.1 14.3 1.9 1,378.7 Interest Expense (140.6 ) (27.2 ) (79.8 ) (35.4 ) 3.4 (279.6 ) Other Income/(Loss), Net 9.6 (0.1 ) 11.9 777.0 (774.5 ) 23.9 Net Income Attributable to Common Shareholders $ 418.9 $ 57.3 $ 225.0 $ 764.7 $ (769.2 ) $ 696.7 Cash Flows Used for Investments in Plant $ 506.5 $ 120.0 $ 493.9 $ 56.9 $ — $ 1,177.3 The following table summarizes Eversource’s segmented total assets: Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Other Eliminations Total As of September 30, 2016 $ 18,140.0 $ 3,149.9 $ 8,454.4 $ 13,624.8 $ (12,286.8 ) $ 31,082.3 As of December 31, 2015 17,981.3 3,104.5 8,019.3 13,256.7 (11,781.5 ) 30,580.3

SUMMARY OF SIGNIFICANT ACCOUN21

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Eversource Energy is a public utility holding company primarily engaged, through its wholly owned regulated utility subsidiaries, in the energy delivery business. Eversource Energy’s wholly owned regulated utility subsidiaries consist of CL&P, NSTAR Electric, PSNH, WMECO, Yankee Gas and NSTAR Gas. Eversource provides energy delivery service to approximately 3.6 million electric and natural gas customers through these six regulated utilities in Connecticut, Massachusetts and New Hampshire. The unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH include the accounts of each of their respective subsidiaries. Intercompany transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH and the unaudited condensed financial statements of CL&P and WMECO are herein collectively referred to as the “financial statements.” The combined notes to the financial statements have been prepared pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures included in annual financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. The accompanying financial statements should be read in conjunction with the Combined Notes to Financial Statements included in Item 8, “Financial Statements and Supplementary Data,” of the Eversource 2015 Form 10-K, which was filed with the SEC. The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The financial statements contain, in the opinion of management, all adjustments (including normal, recurring adjustments) necessary to present fairly Eversource’s, CL&P’s, NSTAR Electric’s, PSNH’s and WMECO’s financial position as of September 30, 2016 and December 31, 2015 , the results of operations and comprehensive income for the three and nine months ended September 30, 2016 and 2015 , and the cash flows for the nine months ended September 30, 2016 and 2015 . The results of operations and comprehensive income for the three and nine months ended September 30, 2016 and 2015 and the cash flows for the nine months ended September 30, 2016 and 2015 are not necessarily indicative of the results expected for a full year. Eversource consolidates CYAPC and YAEC because CL&P’s, NSTAR Electric’s, PSNH’s and WMECO’s combined ownership interest in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and WMECO and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements. Access Northeast is a natural gas pipeline and storage project (the Project) being developed jointly by Eversource, Spectra Energy Partners, LP (Spectra), and National Grid plc (National Grid) through Algonquin Gas Transmission, LLC (AGT). The Project will enhance the Algonquin and Maritimes & Northeast pipeline systems using existing routes and will include two new LNG storage tanks and liquefaction and vaporization facilities in Acushnet, Massachusetts that will be connected to the Algonquin natural gas pipeline. Eversource and Spectra each own a 40 percent interest in the Project, with the remaining 20 percent interest owned by National Grid. The total projected cost for both the pipeline and the LNG storage facilities will be funded in proportion to the respective ownership interest. Eversource’s cumulative equity investment in the Project as of September 30, 2016 of $28.6 million is presented in Other Long-Term Assets. Eversource’s utility subsidiaries’ distribution (including generation) and transmission businesses are subject to rate-regulation that is based on cost recovery and meets the criteria for application of accounting guidance for entities with rate-regulated operations, which considers the effect of regulation on the differences in the timing of the recognition of certain revenues and expenses from those of other businesses and industries. See Note 2, “Regulatory Accounting,” for further information. Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation and as a result of the adoption of new accounting guidance. See Note 1B, “Summary of Significant Accounting Policies – Accounting Standards,” for further information.
Accounting Standards	Accounting Standards Accounting Standards Issued but not Yet Effective: In May 2014, the Financial Accounting Standards Board (FASB) issued an Accounting Standards Update (ASU) 2014-9, Revenue from Contracts with Customers , which amends existing revenue recognition guidance and is required to be applied retrospectively (either to each reporting period presented or cumulatively at the date of initial application). In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers – Deferral of the Effective Date , which defers the effective date of ASU 2014-9 to the first quarter of 2018, with 2017 application permitted. The guidance continues to be interpreted on an industry specific level. The Company is evaluating the requirements and potential impacts of ASU 2014-9 and will implement the standard in the first quarter of 2018. The ASU is not currently expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric, PSNH or WMECO. In January 2016, the FASB issued ASU 2016-1, Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Liabilities , which is required to be implemented in the first quarter of 2018. The Company is reviewing the requirements of the ASU. The ASU will remove the available-for-sale designation for equity securities, whereby changes in fair value are recorded in accumulated other comprehensive income within shareholders’ equity, and will require changes in fair value of all equity securities to be recorded in earnings beginning on January 1, 2018, with the unrealized gain or loss on available-for-sale equity securities as of that date reclassified to retained earnings as a cumulative effect of adoption. The fair value of available-for-sale equity securities subject to this guidance as of September 30, 2016 was approximately $50 million . The remaining available-for-sale equity securities included in marketable securities on the balance sheet are held in nuclear decommissioning trusts and are subject to regulatory accounting treatment and will not be impacted by this guidance. Implementation of the ASU for other financial instruments is not expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric, PSNH or WMECO. In February 2016, the FASB issued ASU 2016-2, Leases , which changes existing lease accounting guidance and is required to be applied in the first quarter of 2019, with earlier application permitted. The ASU is required to be implemented for leases beginning on the date of initial application. For prior periods presented, leases are required to be recognized and measured using a modified retrospective approach. The Company is reviewing the requirements of ASU 2016-2, including balance sheet recognition of leases previously deemed operating leases, and expects to implement the ASU in the first quarter of 2019. Recently Adopted Accounting Standards: In March 2016, the FASB issued ASU 2016-9, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting . The ASU is intended to simplify some aspects of the accounting for share-based payment transactions. The Company implemented this guidance in the first quarter of 2016, as permitted by early adoption. Beginning in the first quarter of 2016, the excess tax benefits associated with the distribution of stock compensation awards, previously recognized in Capital Surplus, Paid In within Common Shareholders’ Equity on the balance sheet, are recognized in income tax expense in the income statement. The implementation reduced income tax expense by $2.9 million for the nine months ended September 30, 2016 . Also, beginning in 2016, in the statement of cash flows, the excess tax benefits are presented as an operating activity rather than a financing activity, and in both periods presented, cash paid to satisfy the statutory income tax withholding obligation previously reflected within operating activities in 2015 is now treated as a financing activity. The cash payments to satisfy this obligation for the nine months ended September 30, 2016 and 2015 were $9.1 million and $9.7 million , respectively, and are included in Other Financing Activities on the statements of cash flows.
Provision for Uncollectible Accounts	Provision for Uncollectible Accounts Eversource, including CL&P, NSTAR Electric, PSNH and WMECO, presents its receivables at estimated net realizable value by maintaining a provision for uncollectible accounts. This provision is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. The estimate is based upon historical collection and write-off experience and management’s assessment of collectability from customers. Management continuously assesses the collectability of receivables and adjusts collectability estimates based on actual experience. Receivable balances are written off against the provision for uncollectible accounts when the customer accounts are terminated and these balances are deemed to be uncollectible. The PURA allows CL&P and Yankee Gas to accelerate the recovery of accounts receivable balances attributable to qualified customers under financial or medical duress (uncollectible hardship accounts receivable) outstanding for greater than 180 days and 90 days, respectively. The DPU allows WMECO and NSTAR Gas to also recover in rates amounts associated with certain uncollectible hardship accounts receivable. Certain of NSTAR Electric’s uncollectible hardship accounts receivable are expected to be recovered in future rates, similar to WMECO and NSTAR Gas. These uncollectible customer account balances are included in Regulatory Assets or Other Long-Term Assets on the balance sheets.
Fair Value Measurements	Fair Value Measurements Fair value measurement guidance is applied to derivative contracts that are not elected or designated as “normal purchases or normal sales” (normal) and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill and AROs, and the estimated fair value of preferred stock and long-term debt. Fair Value Hierarchy: In measuring fair value, Eversource uses observable market data when available in order to minimize the use of unobservable inputs. Inputs used in fair value measurements are categorized into three fair value hierarchy levels for disclosure purposes. The entire fair value measurement is categorized based on the lowest level of input that is significant to the fair value measurement. Eversource evaluates the classification of assets and liabilities measured at fair value on a quarterly basis, and Eversource’s policy is to recognize transfers between levels of the fair value hierarchy as of the end of the reporting period. The three levels of the fair value hierarchy are described below: Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 - Inputs are quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs are observable. Level 3 - Quoted market prices are not available. Fair value is derived from valuation techniques in which one or more significant inputs or assumptions are unobservable. Where possible, valuation techniques incorporate observable market inputs that can be validated to external sources such as industry exchanges, including prices of energy and energy-related products.
Other Income, Net	Other Income, Net Items included within Other Income, Net on the statements of income primarily consist of investment income/(loss), interest income, AFUDC related to equity funds, and equity in earnings of equity method investees. Investment income/(loss) primarily relates to debt and equity securities held in trust. For further information, see Note 5, “Marketable Securities,” to the financial statements.
Other Taxes	As agents for state and local governments, Eversource’s companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income. Other Taxes Gross receipts taxes levied by the state of Connecticut are collected by CL&P and Yankee Gas from their respective customers.

SUMMARY OF SIGNIFICANT ACCOUN22

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	The total provisions for uncollectible accounts and for uncollectible hardship accounts, which is included in the total provision, are included in Receivables, Net on the balance sheets, and were as follows: Total Provision for Uncollectible Accounts Uncollectible Hardship (Millions of Dollars) As of September 30, 2016 As of December 31, 2015 As of September 30, 2016 As of December 31, 2015 Eversource $ 208.1 $ 190.7 $ 126.5 $ 118.5 CL&P 85.3 79.5 66.9 68.1 NSTAR Electric 59.9 52.6 30.3 25.3 PSNH 9.9 8.7 — — WMECO 16.8 14.0 10.7 7.4
State Of Connecticut Gross Earnings Taxes	These gross receipts taxes are shown separately with collections in Operating Revenues and with payments in Taxes Other Than Income Taxes on the statements of income as follows: For the Three Months Ended For the Nine Months Ended (Millions of Dollars) September 30, 2016 September 30, 2015 September 30, 2016 September 30, 2015 Eversource $ 45.1 $ 37.8 $ 124.8 $ 112.9 CL&P 42.6 35.5 112.2 98.0
Schedule of Supplemental Cash Flow Information	Non-cash investing activities include plant additions included in Accounts Payable as follows: (Millions of Dollars) As of September 30, 2016 As of September 30, 2015 Eversource $ 203.6 $ 160.7 CL&P 64.5 46.0 NSTAR Electric 39.4 31.2 PSNH 31.0 33.8 WMECO 17.6 15.5

REGULATORY ACCOUNTING (Tables)

REGULATORY ACCOUNTING (Tables)	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Schedule of Regulatory Assets	The components of regulatory assets were as follows: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Eversource Eversource Benefit Costs $ 1,618.7 $ 1,828.2 Derivative Liabilities 443.7 388.0 Income Taxes, Net 641.7 650.9 Storm Restoration Costs 407.7 436.9 Goodwill-related 469.5 484.9 Regulatory Tracker Mechanisms 454.1 526.5 Contractual Obligations - Yankee Companies 66.0 134.4 Other Regulatory Assets 120.9 134.0 Total Regulatory Assets 4,222.3 4,583.8 Less: Current Portion 752.4 845.8 Total Long-Term Regulatory Assets $ 3,469.9 $ 3,738.0 As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH WMECO Benefit Costs $ 407.1 $ 414.6 $ 174.7 $ 82.1 $ 413.6 $ 479.9 $ 164.2 $ 84.9 Derivative Liabilities 441.0 2.7 — — 380.8 1.3 — — Income Taxes, Net 438.5 88.3 27.0 31.2 444.4 85.7 34.5 31.8 Storm Restoration Costs 253.7 115.1 20.8 18.1 271.4 110.9 31.5 23.1 Goodwill-related — 403.1 — — — 416.3 — — Regulatory Tracker Mechanisms 50.6 230.4 99.9 37.8 45.1 311.0 101.2 40.1 Other Regulatory Assets 75.4 48.2 30.8 13.2 82.0 56.3 31.5 11.3 Total Regulatory Assets 1,666.3 1,302.4 353.2 182.4 1,637.3 1,461.4 362.9 191.2 Less: Current Portion 267.7 259.2 100.6 54.1 268.3 348.4 105.0 56.2 Total Long-Term Regulatory Assets $ 1,398.6 $ 1,043.2 $ 252.6 $ 128.3 $ 1,369.0 $ 1,113.0 $ 257.9 $ 135.0
Schedule of Regulatory Liabilities	The components of regulatory liabilities were as follows: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Eversource Eversource Cost of Removal $ 457.7 $ 437.1 Regulatory Tracker Mechanisms 153.4 99.7 AFUDC - Transmission 65.8 66.1 Other Regulatory Liabilities 33.7 18.5 Total Regulatory Liabilities 710.6 621.4 Less: Current Portion 160.4 107.8 Total Long-Term Regulatory Liabilities $ 550.2 $ 513.6 As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH WMECO Cost of Removal $ 39.7 $ 269.5 $ 45.8 $ 5.8 $ 24.1 $ 257.4 $ 47.2 $ 2.8 Benefit Costs — 81.7 — — — — — — Regulatory Tracker Mechanisms 62.2 48.4 2.6 12.2 56.2 3.3 3.4 12.9 AFUDC - Transmission 50.6 6.4 — 8.8 51.5 5.7 — 8.9 Other Regulatory Liabilities 12.8 — 3.5 — 4.2 1.3 4.2 0.1 Total Regulatory Liabilities 165.3 406.0 51.9 26.8 136.0 267.7 54.8 24.7 Less: Current Portion 75.7 48.8 5.5 12.4 61.2 3.3 6.9 13.1 Total Long-Term Regulatory Liabilities $ 89.6 $ 357.2 $ 46.4 $ 14.4 $ 74.8 $ 264.4 $ 47.9 $ 11.6

PROPERTY, PLANT AND EQUIPMENT24

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Tables)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Public Utility Property, Plant, and Equipment	The following tables summarize the investments in utility property, plant and equipment by asset category: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Eversource Eversource Distribution - Electric $ 13,536.1 $ 13,054.8 Distribution - Natural Gas 2,865.8 2,727.2 Transmission - Electric 8,033.0 7,691.9 Generation 1,218.9 1,194.1 Electric and Natural Gas Utility 25,653.8 24,668.0 Other (1) 635.3 558.6 Property, Plant and Equipment, Gross 26,289.1 25,226.6 Less: Accumulated Depreciation Electric and Natural Gas Utility (6,442.3 ) (6,141.1 ) Other (285.8 ) (255.6 ) Total Accumulated Depreciation (6,728.1 ) (6,396.7 ) Property, Plant and Equipment, Net 19,561.0 18,829.9 Construction Work in Progress 1,246.9 1,062.5 Total Property, Plant and Equipment, Net $ 20,807.9 $ 19,892.4 (1) These assets are primarily comprised of building improvements, computer software, hardware and equipment at Eversource Service. As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH WMECO Distribution $ 5,513.9 $ 5,309.2 $ 1,918.3 $ 834.6 $ 5,377.2 $ 5,100.5 $ 1,804.8 $ 812.3 Transmission 3,752.7 2,211.7 1,005.5 1,014.9 3,618.0 2,131.3 928.2 964.9 Generation — — 1,182.9 36.0 — — 1,158.1 36.0 Property, Plant and Equipment, Gross 9,266.6 7,520.9 4,106.7 1,885.5 8,995.2 7,231.8 3,891.1 1,813.2 Less: Accumulated Depreciation (2,102.3 ) (1,996.8 ) (1,243.8 ) (330.6 ) (2,041.9 ) (1,886.8 ) (1,171.0 ) (307.0 ) Property, Plant and Equipment, Net 7,164.3 5,524.1 2,862.9 1,554.9 6,953.3 5,345.0 2,720.1 1,506.2 Construction Work in Progress 288.9 351.8 110.2 88.4 203.5 310.5 135.3 69.1 Total Property, Plant and Equipment, Net $ 7,453.2 $ 5,875.9 $ 2,973.1 $ 1,643.3 $ 7,156.8 $ 5,655.5 $ 2,855.4 $ 1,575.3

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table presents the gross fair values of contracts, categorized by risk type, and the net amounts recorded as current or long-term derivative assets or liabilities: As of September 30, 2016 As of December 31, 2015 (Millions of Dollars) Commodity Supply and Price Risk Management Netting (1) Net Amount Recorded as a Derivative Commodity Supply and Price Risk Netting (1) Net Amount Recorded as a Derivative Current Derivative Assets: Level 2: Eversource $ 2.6 $ (0.2 ) $ 2.4 $ — $ — $ — Level 3: Eversource 15.7 (10.4 ) 5.3 16.7 (10.9 ) 5.8 CL&P 15.3 (10.4 ) 4.9 16.7 (10.9 ) 5.8 NSTAR Electric 0.4 — 0.4 — — — Long-Term Derivative Assets: Level 2: Eversource $ — $ — $ — $ 0.1 $ — $ 0.1 Level 3: Eversource 79.3 (13.8 ) 65.5 62.0 (19.3 ) 42.7 CL&P 79.3 (13.8 ) 65.5 60.7 (19.3 ) 41.4 NSTAR Electric — — — 1.3 — 1.3 Current Derivative Liabilities: Level 2: Eversource $ — $ — $ — $ (5.8 ) $ — $ (5.8 ) Level 3: Eversource (87.1 ) — (87.1 ) (92.3 ) — (92.3 ) CL&P (85.3 ) — (85.3 ) (91.8 ) — (91.8 ) NSTAR Electric (1.8 ) — (1.8 ) (0.5 ) — (0.5 ) Long-Term Derivative Liabilities: Level 3: Eversource $ (427.4 ) $ — $ (427.4 ) $ (337.1 ) $ — $ (337.1 ) CL&P (426.1 ) — (426.1 ) (336.2 ) — (336.2 ) NSTAR Electric (1.3 ) — (1.3 ) (0.9 ) — (0.9 ) (1) Amounts represent derivative assets and liabilities that Eversource elected to record net on the balance sheets. These amounts are subject to master netting agreements or similar agreements for which the right of offset exists.
Fair Value Inputs, Liabilities, Quantitative Information	The following is a summary of Eversource’s, including CL&P’s and NSTAR Electric’s, Level 3 derivative contracts and the range of the significant unobservable inputs utilized in the valuations over the duration of the contracts: As of September 30, 2016 As of December 31, 2015 Range Period Covered Range Period Covered Capacity Prices: Eversource $ 5.50 — 9.75 per kW-Month 2020 - 2026 $ 10.81 — 15.82 per kW-Month 2016 - 2026 CL&P $ 5.50 — 9.75 per kW-Month 2020 - 2026 $ 10.81 — 12.60 per kW-Month 2019 - 2026 Forward Reserve: Eversource, CL&P $ 1.40 — 2.00 per kW-Month 2016 - 2024 $2.00 per kW-Month 2016 - 2024 REC Prices: Eversource, NSTAR Electric $ 29 — 37 per REC 2016 - 2018 $ 45 — 51 per REC 2016 - 2018
Rollforward Of Net Derivative Asset Liabilities Valued Using Unobservable Inputs	The following table presents changes in the Level 3 category of derivative assets and derivative liabilities measured at fair value on a recurring basis. The derivative assets and liabilities are presented on a net basis. For the Three Months Ended September 30, 2016 2015 (Millions of Dollars) Eversource CL&P NSTAR Electric Eversource CL&P NSTAR Derivatives, Net: Fair Value as of Beginning of Period $ (412.6 ) $ (411.3 ) $ (1.3 ) $ (422.4 ) $ (420.2 ) $ (2.2 ) Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets and Liabilities (52.3 ) (49.8 ) (2.5 ) (6.0 ) (7.6 ) 1.6 Settlements 21.2 20.1 1.1 21.4 20.9 0.5 Fair Value as of End of Period $ (443.7 ) $ (441.0 ) $ (2.7 ) $ (407.0 ) $ (406.9 ) $ (0.1 ) For the Nine Months Ended September 30, 2016 2015 (Millions of Dollars) Eversource CL&P NSTAR Eversource CL&P NSTAR Derivatives, Net: Fair Value as of Beginning of Period $ (380.9 ) $ (380.8 ) $ (0.1 ) $ (415.4 ) $ (410.9 ) $ (4.5 ) Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets and Liabilities (128.9 ) (122.0 ) (6.9 ) (55.3 ) (56.6 ) 1.3 Settlements 66.1 61.8 4.3 63.7 60.6 3.1 Fair Value as of End of Period $ (443.7 ) $ (441.0 ) $ (2.7 ) $ (407.0 ) $ (406.9 ) $ (0.1 )

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities Reconciliation	The following is a summary of available-for-sale securities, which are recorded at fair value and are included in current and long-term Marketable Securities on the balance sheets. As of September 30, 2016 As of December 31, 2015 Eversource (Millions of Dollars) Amortized Cost Pre-Tax Unrealized Gains Pre-Tax Unrealized Losses Fair Value Amortized Cost Pre-Tax Unrealized Gains Pre-Tax Unrealized Losses Fair Value Debt Securities $ 261.2 $ 10.7 $ — $ 271.9 $ 256.5 $ 4.5 $ (0.6 ) $ 260.4 Equity Securities 206.7 63.7 (1.0 ) 269.4 215.3 59.2 (3.4 ) 271.1
Investments Classified by Contractual Maturity Date	As of September 30, 2016 , the contractual maturities of available-for-sale debt securities were as follows: Eversource (Millions of Dollars) Amortized Cost Fair Value Less than one year (1) $ 29.3 $ 29.1 One to five years 58.0 59.1 Six to ten years 47.0 49.5 Greater than ten years 126.9 134.2 Total Debt Securities $ 261.2 $ 271.9 (1) Amounts in the Less than one year category include securities in the CYAPC and YAEC nuclear decommissioning trusts, which are restricted and are classified in long-term Marketable Securities on the balance sheets.
Fair Value on a Recurring Basis	The following table presents the marketable securities recorded at fair value on a recurring basis by the level in which they are classified within the fair value hierarchy: Eversource (Millions of Dollars) As of September 30, 2016 As of December 31, 2015 Level 1: Mutual Funds and Equities $ 279.7 $ 285.3 Money Market Funds 24.5 26.9 Total Level 1 $ 304.2 $ 312.2 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 65.5 $ 46.6 Corporate Debt Securities 43.3 43.9 Asset-Backed Debt Securities 18.0 20.0 Municipal Bonds 110.3 111.4 Other Fixed Income Securities 10.3 11.6 Total Level 2 $ 247.4 $ 233.5 Total Marketable Securities $ 551.6 $ 545.7

PENSION BENEFITS AND POSTRETI27

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSIONS (Tables)	9 Months Ended
	Sep. 30, 2016
Postemployment Benefits [Abstract]
Schedule of Net Benefit Costs	The components of net periodic benefit expense for the Pension, SERP and PBOP Plans are shown below. The net periodic benefit expense and the intercompany allocations, less the capitalized portions of pension, SERP and PBOP amounts, are included in Operations and Maintenance expense on the statements of income. Capitalized pension and PBOP amounts relate to employees working on capital projects and are included in Property, Plant and Equipment, Net on the balance sheets. Pension, SERP and PBOP expense reflected in the statements of cash flows for CL&P, NSTAR Electric, PSNH and WMECO does not include the intercompany allocations or the corresponding capitalized portion, as these amounts are cash settled on a short-term basis. Pension and SERP Eversource For the Three Months Ended For the Nine Months Ended (Millions of Dollars) September 30, 2016 September 30, 2015 (1) September 30, 2016 September 30, 2015 (1) Service Cost $ 18.6 $ 22.7 $ 56.6 $ 68.7 Interest Cost 46.4 56.9 139.2 170.3 Expected Return on Plan Assets (79.4 ) (83.9 ) (238.5 ) (252.1 ) Actuarial Loss 31.4 36.5 94.2 111.9 Prior Service Cost 0.9 0.9 2.6 2.7 Total Net Periodic Benefit Expense $ 17.9 $ 33.1 $ 54.1 $ 101.5 Capitalized Pension Expense $ 5.4 $ 9.8 $ 16.8 $ 31.3 PBOP Eversource For the Three Months Ended For the Nine Months Ended (Millions of Dollars) September 30, 2016 September 30, 2015 (1) September 30, 2016 September 30, 2015 (1) Service Cost $ 3.0 $ 4.1 $ 9.2 $ 10.3 Interest Cost 7.5 11.8 26.5 30.4 Expected Return on Plan Assets (15.9 ) (16.9 ) (47.3 ) (43.2 ) Actuarial Loss 3.0 1.7 5.0 4.5 Prior Service Credit (3.6 ) (0.1 ) (3.7 ) (0.3 ) Total Net Periodic Benefit Expense/(Income) $ (6.0 ) $ 0.6 $ (10.3 ) $ 1.7 Capitalized PBOP Expense/(Income) $ (2.6 ) $ — $ (4.6 ) $ 0.1 Pension and SERP For the Three Months Ended September 30, 2016 For the Three Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 4.6 $ 3.3 $ 2.5 $ 0.8 $ 6.2 $ 3.7 $ 3.1 $ 1.0 Interest Cost 10.2 8.5 5.1 2.1 12.9 10.0 6.1 2.6 Expected Return on Plan Assets (18.0 ) (16.9 ) (9.6 ) (4.4 ) (19.8 ) (17.5 ) (10.1 ) (4.7 ) Actuarial Loss 6.3 8.7 2.5 1.3 8.0 8.7 2.9 1.6 Prior Service Cost 0.4 — 0.1 0.1 0.4 — 0.1 0.1 Total Net Periodic Benefit Expense/(Income) $ 3.5 $ 3.6 $ 0.6 $ (0.1 ) $ 7.7 $ 4.9 $ 2.1 $ 0.6 Intercompany Allocations $ 3.5 $ 2.2 $ 1.0 $ 0.6 $ 5.8 $ 3.4 $ 1.6 $ 1.1 Capitalized Pension Expense $ 2.2 $ 2.0 $ 0.4 $ 0.1 $ 4.7 $ 2.7 $ 0.8 $ 0.5 Pension and SERP For the Nine Months Ended September 30, 2016 For the Nine Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 14.3 $ 9.9 $ 7.5 $ 2.4 $ 18.4 $ 11.2 $ 9.0 $ 3.2 Interest Cost 31.2 25.3 15.4 6.3 38.4 30.2 18.1 7.8 Expected Return on Plan Assets (54.2 ) (50.7 ) (28.9 ) (13.1 ) (59.1 ) (52.5 ) (30.3 ) (14.2 ) Actuarial Loss 19.2 25.8 7.5 4.1 24.2 27.0 8.8 4.8 Prior Service Cost 1.1 — 0.3 0.2 1.1 0.1 0.4 0.2 Total Net Periodic Benefit Expense/(Income) $ 11.6 $ 10.3 $ 1.8 $ (0.1 ) $ 23.0 $ 16.0 $ 6.0 $ 1.8 Intercompany Allocations $ 10.3 $ 6.7 $ 3.0 $ 1.9 $ 18.0 $ 10.3 $ 5.0 $ 3.3 Capitalized Pension Expense $ 7.1 $ 5.7 $ 1.0 $ 0.3 $ 14.1 $ 8.6 $ 2.6 $ 1.4 PBOP For the Three Months Ended September 30, 2016 For the Three Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 0.6 $ 0.6 $ 0.4 $ 0.1 $ 0.5 $ 1.3 $ 0.3 $ 0.1 Interest Cost 1.3 2.5 0.7 0.3 1.8 4.8 1.0 0.3 Expected Return on Plan Assets (2.5 ) (6.4 ) (1.4 ) (0.6 ) (2.8 ) (6.8 ) (1.5 ) (0.6 ) Actuarial Loss 0.5 1.2 0.2 — 0.2 0.6 0.1 — Prior Service Cost/(Credit) 0.2 (2.9 ) 0.1 — — (0.1 ) — — Total Net Periodic Benefit Expense/(Income) $ 0.1 $ (5.0 ) $ — $ (0.2 ) $ (0.3 ) $ (0.2 ) $ (0.1 ) $ (0.2 ) Intercompany Allocations $ — $ (0.1 ) $ — $ — $ 0.4 $ 0.2 $ 0.1 $ 0.1 Capitalized PBOP Expense/(Income) $ — $ (2.2 ) $ — $ (0.1 ) $ (0.1 ) $ — $ 0.1 $ — PBOP For the Nine Months Ended September 30, 2016 For the Nine Months Ended September 30, 2015 (Millions of Dollars) CL&P NSTAR Electric PSNH WMECO CL&P NSTAR Electric PSNH (1) WMECO Service Cost $ 1.4 $ 2.5 $ 0.9 $ 0.3 $ 1.6 $ 4.0 $ 1.0 $ 0.3 Interest Cost 4.0 10.3 2.2 0.8 5.4 14.2 2.9 1.1 Expected Return on Plan Assets (7.6 ) (19.2 ) (4.2 ) (1.7 ) (8.3 ) (20.5 ) (4.4 ) (1.9 ) Actuarial Loss 0.9 1.7 0.5 — 0.5 1.8 0.4 — Prior Service Cost/(Credit) 0.2 (2.9 ) 0.1 — — (0.1 ) — — Total Net Periodic Benefit Income $ (1.1 ) $ (7.6 ) $ (0.5 ) $ (0.6 ) $ (0.8 ) $ (0.6 ) $ (0.1 ) $ (0.5 ) Intercompany Allocations $ 0.3 $ — $ — $ — $ 1.4 $ 0.7 $ 0.3 $ 0.3 Capitalized PBOP Expense/(Income) $ (0.5 ) $ (3.3 ) $ — $ (0.3 ) $ (0.2 ) $ (0.1 ) $ 0.2 $ (0.1 ) (1) Amounts excluded approximately $0.8 million and $2.4 million for the three and nine months ended September 30, 2015 , respectively, that represented amounts included in other deferred debits.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of Environmental Loss Contingencies by Site	The number of environmental sites and related reserves for which remediation or long-term monitoring, preliminary site work or site assessment is being performed are as follows: As of September 30, 2016 As of December 31, 2015 Number of Sites Reserve (in millions) Number of Sites Reserve (in millions) Eversource 63 $ 59.7 64 $ 51.1 CL&P 14 4.7 14 4.6 NSTAR Electric 14 2.3 15 2.4 PSNH 12 4.3 12 4.5 WMECO 4 0.7 4 0.6
Schedule of Guarantor Obligations	The following table summarizes Eversource parent’s exposure to guarantees and indemnifications of its subsidiaries to external parties, as of September 30, 2016 : Company Description Maximum Exposure (in millions) Expiration Dates On behalf of subsidiaries: Eversource Gas Transmission LLC Access Northeast Project Capital Contributions Guaranty $ 186.5 2021 Various Surety Bonds (1) $ 37.1 2016 - 2018 Eversource Service and Rocky River Realty Company Lease Payments for Vehicles and Real Estate $ 9.8 2019 - 2024 (1) Surety bond expiration dates reflect termination dates, the majority of which will be renewed or extended. Certain surety bonds contain credit ratings triggers that would require Eversource parent to post collateral in the event that the unsecured debt credit ratings of Eversource parent are downgraded.

PSNH GENERATION ASSET SALE - (T

PSNH GENERATION ASSET SALE - (Tables)	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Schedule of Generation Assets and Liabilities	As of September 30, 2016, PSNH’s generation assets were as follows: (Millions of Dollars) Gross Plant $ 1,191.0 Accumulated Depreciation (552.1 ) Net Plant 638.9 Fuel, Materials, Supplies and Allowances 161.9

FAIR VALUE OF FINANCIAL INSTR30

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping	Carrying amounts and estimated fair values are as follows: As of September 30, 2016 As of December 31, 2015 Eversource (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 166.6 $ 155.6 $ 157.9 Long-Term Debt 9,609.0 10,454.8 9,034.5 9,425.9 CL&P NSTAR Electric PSNH WMECO (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value As of September 30, 2016: Preferred Stock Not Subject to Mandatory Redemption $ 116.2 $ 122.2 $ 43.0 $ 44.4 $ — $ — $ — $ — Long-Term Debt 2,765.4 3,216.8 2,078.0 2,338.8 1,071.8 1,142.9 566.7 616.9 As of December 31, 2015: Preferred Stock Not Subject to Mandatory Redemption $ 116.2 $ 114.9 $ 43.0 $ 43.0 $ — $ — $ — $ — Long-Term Debt 2,763.7 3,031.6 2,029.8 2,182.4 1,071.0 1,121.2 517.3 551.8

ACCUMULATED OTHER COMPREHENSI31

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The changes in accumulated other comprehensive income/(loss) by component, net of tax, is as follows: For the Nine Months Ended September 30, 2016 For the Nine Months Ended September 30, 2015 Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Eversource (Millions of Dollars) Balance as of Beginning of Period $ (10.3 ) $ (1.9 ) $ (54.6 ) $ (66.8 ) $ (12.4 ) $ 0.7 $ (62.3 ) $ (74.0 ) OCI Before Reclassifications — 2.3 (5.3 ) (3.0 ) — (3.9 ) (0.4 ) (4.3 ) Amounts Reclassified from AOCI 1.6 — 2.6 4.2 1.5 — 3.3 4.8 Net OCI 1.6 2.3 (2.7 ) 1.2 1.5 (3.9 ) 2.9 0.5 Balance as of End of Period $ (8.7 ) $ 0.4 $ (57.3 ) $ (65.6 ) $ (10.9 ) $ (3.2 ) $ (59.4 ) $ (73.5 )

COMMON SHARES (Tables)

COMMON SHARES (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Schedule of Stock by Class	The following table sets forth the Eversource parent common shares and the shares of common stock of CL&P, NSTAR Electric, PSNH and WMECO that were authorized and issued as well as the respective per share par values: Shares Authorized as of September 30, 2016 and Issued as of Par Value December 31, 2015 September 30, 2016 December 31, 2015 Eversource $ 5 380,000,000 333,878,402 333,862,615 CL&P $ 10 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 100 100 PSNH $ 1 100,000,000 301 301 WMECO $ 25 1,072,471 434,653 434,653

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the components of basic and diluted EPS: Eversource (Millions of Dollars, except share information) For the Three Months Ended For the Nine Months Ended September 30, 2016 September 30, 2015 September 30, 2016 September 30, 2015 Net Income Attributable to Common Shareholders $ 265.3 $ 235.9 $ 713.1 $ 696.7 Weighted Average Common Shares Outstanding: Basic 317,787,836 317,452,212 317,696,823 317,296,107 Dilutive Effect 789,243 953,057 814,786 1,099,935 Diluted 318,577,079 318,405,269 318,511,609 318,396,042 Basic EPS $ 0.83 $ 0.74 $ 2.24 $ 2.20 Diluted EPS $ 0.83 $ 0.74 $ 2.24 $ 2.19

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Eversource’s segment information is as follows: For the Three Months Ended September 30, 2016 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 1,623.4 $ 99.2 $ 306.8 $ 211.5 $ (201.2 ) $ 2,039.7 Depreciation and Amortization (154.8 ) (15.2 ) (47.1 ) (8.6 ) 0.5 (225.2 ) Other Operating Expenses (1,146.8 ) (87.8 ) (90.2 ) (179.3 ) 199.5 (1,304.6 ) Operating Income/(Loss) 321.8 (3.8 ) 169.5 23.6 (1.2 ) 509.9 Interest Expense (49.0 ) (10.2 ) (26.9 ) (15.1 ) 1.3 (99.9 ) Other Income, Net 5.3 0.6 6.3 256.9 (255.5 ) 13.6 Net Income Attributable to Common Shareholders $ 170.1 $ (7.0 ) $ 88.4 $ 268.5 $ (254.7 ) $ 265.3 For the Nine Months Ended September 30, 2016 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 4,362.6 $ 622.3 $ 892.5 $ 636.8 $ (651.7 ) $ 5,862.5 Depreciation and Amortization (380.9 ) (47.9 ) (137.7 ) (23.1 ) 1.6 (588.0 ) Other Operating Expenses (3,230.1 ) (462.4 ) (245.7 ) (564.7 ) 650.2 (3,852.7 ) Operating Income 751.6 112.0 509.1 49.0 0.1 1,421.8 Interest Expense (144.6 ) (30.8 ) (82.2 ) (45.8 ) 4.8 (298.6 ) Other Income, Net 11.6 0.5 14.2 781.4 (784.0 ) 23.7 Net Income Attributable to Common Shareholders $ 381.3 $ 51.9 $ 266.6 $ 791.7 $ (778.4 ) $ 713.1 Cash Flows Used for Investments in Plant $ 570.9 $ 170.3 $ 536.2 $ 81.8 $ — $ 1,359.2 For the Three Months Ended September 30, 2015 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 1,543.7 $ 106.2 $ 270.4 $ 211.6 $ (198.8 ) $ 1,933.1 Depreciation and Amortization (84.5 ) (17.5 ) (42.4 ) (7.1 ) 0.5 (151.0 ) Other Operating Expenses (1,140.8 ) (92.7 ) (78.3 ) (199.6 ) 198.5 (1,312.9 ) Operating Income/(Loss) 318.4 (4.0 ) 149.7 4.9 0.2 469.2 Interest Expense (47.4 ) (9.2 ) (25.9 ) (11.2 ) 1.2 (92.5 ) Other Income/(Loss), Net 1.9 (0.2 ) 3.8 241.9 (242.2 ) 5.2 Net Income Attributable to Common Shareholders $ 167.5 $ (3.7 ) $ 78.0 $ 234.9 $ (240.8 ) $ 235.9 For the Nine Months Ended September 30, 2015 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Other Eliminations Total Operating Revenues $ 4,686.5 $ 799.6 $ 787.2 $ 655.2 $ (664.9 ) $ 6,263.6 Depreciation and Amortization (342.1 ) (53.4 ) (122.6 ) (21.5 ) 1.6 (538.0 ) Other Operating Expenses (3,535.7 ) (631.5 ) (225.5 ) (619.4 ) 665.2 (4,346.9 ) Operating Income 808.7 114.7 439.1 14.3 1.9 1,378.7 Interest Expense (140.6 ) (27.2 ) (79.8 ) (35.4 ) 3.4 (279.6 ) Other Income/(Loss), Net 9.6 (0.1 ) 11.9 777.0 (774.5 ) 23.9 Net Income Attributable to Common Shareholders $ 418.9 $ 57.3 $ 225.0 $ 764.7 $ (769.2 ) $ 696.7 Cash Flows Used for Investments in Plant $ 506.5 $ 120.0 $ 493.9 $ 56.9 $ — $ 1,177.3 The following table summarizes Eversource’s segmented total assets: Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Other Eliminations Total As of September 30, 2016 $ 18,140.0 $ 3,149.9 $ 8,454.4 $ 13,624.8 $ (12,286.8 ) $ 31,082.3 As of December 31, 2015 17,981.3 3,104.5 8,019.3 13,256.7 (11,781.5 ) 30,580.3

SUMMARY OF SIGNIFICANT ACCOUN35

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Basis of Presentation (Details) customer in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)customerutility
Schedule of Equity Method Investments [Line Items]
Number of electric and natural gas customers | customer	3.6
Connecticut, Massachusetts and New Hampshire [Member]
Schedule of Equity Method Investments [Line Items]
Number of regulated utilities | utility	6
Spectra Energy Corporation [Member] | Access Northeast [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in Access Northeast	40.00%
Eversource [Member] | Access Northeast [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in Access Northeast	40.00%
National Grid [Member] | Access Northeast [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in Access Northeast	20.00%
Other Noncurrent Assets [Member] | Eversource [Member] | Access Northeast [Member]
Schedule of Equity Method Investments [Line Items]
Equity interest in project | $	$ 28.6

SUMMARY OF SIGNIFICANT ACCOUN36

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounting Standards (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Accounting Policies [Abstract]
Available for sale securities subject to new accounting guidance	$ 50
Impact of share based compensation accounting guidance on income tax	2.9
Impact of new accounting standard on cash flow statement	$ 9.1	$ 9.7

SUMMARY OF SIGNIFICANT ACCOUN37

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for Uncollectible Accounts Narrative (Details)	9 Months Ended
	Sep. 30, 2016
Maximum [Member] | The Connecticut Light And Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period of accounts receivable recoverable under financial or medical duress	180 days
Minimum [Member] | Yankee Gas Services Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period of accounts receivable recoverable under financial or medical duress	90 days

SUMMARY OF SIGNIFICANT ACCOUN38

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for Uncollectible Accounts (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	$ 208.1	$ 190.7
Uncollectible Hardship	126.5	118.5
The Connecticut Light And Power Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	85.3	79.5
Uncollectible Hardship	66.9	68.1
NSTAR Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	59.9	52.6
Uncollectible Hardship	30.3	25.3
Public Service Company Of New Hampshire [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	9.9	8.7
Uncollectible Hardship	0	0
Western Massachusetts Electric Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	16.8	14
Uncollectible Hardship	$ 10.7	$ 7.4

SUMMARY OF SIGNIFICANT ACCOUN39

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Gross Tax Receipts [Line Items]
Excise and sales taxes	$ 45.1	$ 37.8	$ 124.8	$ 112.9
The Connecticut Light And Power Company [Member]
Schedule of Gross Tax Receipts [Line Items]
Excise and sales taxes	$ 42.6	$ 35.5	$ 112.2	$ 98

SUMMARY OF SIGNIFICANT ACCOUN40

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Supplemental Cash Flow (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Schedule of Supplemental Cash Flow [Line Items]
Capital expenditures incurred but not yet paid	$ 203.6	$ 160.7
The Connecticut Light And Power Company [Member]
Schedule of Supplemental Cash Flow [Line Items]
Capital expenditures incurred but not yet paid	64.5	46
NSTAR Electric Company [Member]
Schedule of Supplemental Cash Flow [Line Items]
Capital expenditures incurred but not yet paid	39.4	31.2
Public Service Company Of New Hampshire [Member]
Schedule of Supplemental Cash Flow [Line Items]
Capital expenditures incurred but not yet paid	31	33.8
Western Massachusetts Electric Company [Member]
Schedule of Supplemental Cash Flow [Line Items]
Capital expenditures incurred but not yet paid	$ 17.6	$ 15.5

REGULATORY ACCOUNTING - Compone

REGULATORY ACCOUNTING - Components of Regulatory Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 4,222,300	$ 4,583,800
Less: Current Portion	752,378	845,843
Total Long-Term Regulatory Assets	3,469,879	3,737,960
Benefit Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	1,618,700	1,828,200
Derivative Liabilities [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	443,700	388,000
Income Taxes, Net [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	641,700	650,900
Storm Restoration Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	407,700	436,900
Goodwill-related [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	469,500	484,900
Regulatory Tracker Mechanisms [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	454,100	526,500
Contractusl Obligations - Yankee Companies [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	66,000	134,400
Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	120,900	134,000
The Connecticut Light And Power Company [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	1,666,300	1,637,300
Less: Current Portion	267,733	268,318
Total Long-Term Regulatory Assets	1,398,610	1,369,028
The Connecticut Light And Power Company [Member] | Benefit Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	407,100	413,600
The Connecticut Light And Power Company [Member] | Derivative Liabilities [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	441,000	380,800
The Connecticut Light And Power Company [Member] | Income Taxes, Net [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	438,500	444,400
The Connecticut Light And Power Company [Member] | Storm Restoration Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	253,700	271,400
The Connecticut Light And Power Company [Member] | Goodwill-related [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
The Connecticut Light And Power Company [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	50,600	45,100
The Connecticut Light And Power Company [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	75,400	82,000
NSTAR Electric Company [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	1,302,400	1,461,400
Less: Current Portion	259,213	348,408
Total Long-Term Regulatory Assets	1,043,237	1,112,977
NSTAR Electric Company [Member] | Benefit Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	414,600	479,900
NSTAR Electric Company [Member] | Derivative Liabilities [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	2,700	1,300
NSTAR Electric Company [Member] | Income Taxes, Net [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	88,300	85,700
NSTAR Electric Company [Member] | Storm Restoration Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	115,100	110,900
NSTAR Electric Company [Member] | Goodwill-related [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	403,100	416,300
NSTAR Electric Company [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	230,400	311,000
NSTAR Electric Company [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	48,200	56,300
Public Service Company Of New Hampshire [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	353,200	362,900
Less: Current Portion	100,598	104,971
Total Long-Term Regulatory Assets	252,609	257,873
Public Service Company Of New Hampshire [Member] | Benefit Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	174,700	164,200
Public Service Company Of New Hampshire [Member] | Derivative Liabilities [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
Public Service Company Of New Hampshire [Member] | Income Taxes, Net [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	27,000	34,500
Public Service Company Of New Hampshire [Member] | Storm Restoration Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	20,800	31,500
Public Service Company Of New Hampshire [Member] | Goodwill-related [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
Public Service Company Of New Hampshire [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	99,900	101,200
Public Service Company Of New Hampshire [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	30,800	31,500
Western Massachusetts Electric Company [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	182,400	191,200
Less: Current Portion	54,081	56,166
Total Long-Term Regulatory Assets	128,308	135,010
Western Massachusetts Electric Company [Member] | Benefit Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	82,100	84,900
Western Massachusetts Electric Company [Member] | Derivative Liabilities [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
Western Massachusetts Electric Company [Member] | Income Taxes, Net [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	31,200	31,800
Western Massachusetts Electric Company [Member] | Storm Restoration Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	18,100	23,100
Western Massachusetts Electric Company [Member] | Goodwill-related [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
Western Massachusetts Electric Company [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	37,800	40,100
Western Massachusetts Electric Company [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 13,200	$ 11,300

REGULATORY ACCOUNTING - Regulat

REGULATORY ACCOUNTING - Regulatory Costs in Other Long-Term Assets (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	$ 87.9	$ 75.3
The Connecticut Light And Power Company [Member]
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	4	3.1
NSTAR Electric Company [Member]
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	40.2	35.4
Public Service Company Of New Hampshire [Member]
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	6.1	4.8
Western Massachusetts Electric Company [Member]
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	$ 20.1	$ 16.7

REGULATORY ACCOUNTING - Compo43

REGULATORY ACCOUNTING - Components of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 710,600	$ 621,400
Less: Current Portion	160,442	107,759
Total Long-Term Regulatory Liabilities	550,162	513,595
Cost of Removal [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	457,700	437,100
Regulatory Tracker Mechanisms [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	153,400	99,700
AFUDC - Transmission [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	65,800	66,100
Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	33,700	18,500
The Connecticut Light And Power Company [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	165,300	136,000
Less: Current Portion	75,654	61,155
Total Long-Term Regulatory Liabilities	89,599	74,830
The Connecticut Light And Power Company [Member] | Cost of Removal [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	39,700	24,100
The Connecticut Light And Power Company [Member] | Benefit Costs [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
The Connecticut Light And Power Company [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	62,200	56,200
The Connecticut Light And Power Company [Member] | AFUDC - Transmission [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	50,600	51,500
The Connecticut Light And Power Company [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	12,800	4,200
NSTAR Electric Company [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	406,000	267,700
Less: Current Portion	48,842	3,281
Total Long-Term Regulatory Liabilities	357,168	264,352
NSTAR Electric Company [Member] | Cost of Removal [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	269,500	257,400
NSTAR Electric Company [Member] | Benefit Costs [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	81,700	0
NSTAR Electric Company [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	48,400	3,300
NSTAR Electric Company [Member] | AFUDC - Transmission [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	6,400	5,700
NSTAR Electric Company [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	1,300
Public Service Company Of New Hampshire [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	51,900	54,800
Less: Current Portion	5,519	6,898
Total Long-Term Regulatory Liabilities	46,428	47,851
Public Service Company Of New Hampshire [Member] | Cost of Removal [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	45,800	47,200
Public Service Company Of New Hampshire [Member] | Benefit Costs [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Public Service Company Of New Hampshire [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	2,600	3,400
Public Service Company Of New Hampshire [Member] | AFUDC - Transmission [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Public Service Company Of New Hampshire [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	3,500	4,200
Western Massachusetts Electric Company [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	26,800	24,700
Less: Current Portion	12,384	13,122
Total Long-Term Regulatory Liabilities	14,422	11,597
Western Massachusetts Electric Company [Member] | Cost of Removal [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	5,800	2,800
Western Massachusetts Electric Company [Member] | Benefit Costs [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Western Massachusetts Electric Company [Member] | Regulatory Tracker Mechanisms [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	12,200	12,900
Western Massachusetts Electric Company [Member] | AFUDC - Transmission [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	8,800	8,900
Western Massachusetts Electric Company [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 0	$ 100

PROPERTY, PLANT AND EQUIPMENT44

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION - Investment in Utility Property, plant and equipment by asset (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	$ 13,536,100	$ 13,054,800
Distribution - Natural Gas	2,865,800	2,727,200
Transmission - Electric	8,033,000	7,691,900
Generation	1,218,900	1,194,100
Electric and Natural Gas Utility	25,653,800	24,668,000
Other	635,300	558,600
Property, Plant and Equipment, Gross	26,289,100	25,226,600
Less: Accumulated Depreciation
Electric and Natural Gas Utility	(6,442,300)	(6,141,100)
Other	(285,800)	(255,600)
Total Accumulated Depreciation	(6,728,100)	(6,396,700)
Property, Plant and Equipment, Net	19,561,000	18,829,900
Construction Work in Progress	1,246,900	1,062,500
Net Plant	20,807,943	19,892,441
The Connecticut Light And Power Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	5,513,900	5,377,200
Transmission - Electric	3,752,700	3,618,000
Generation	0	0
Property, Plant and Equipment, Gross	9,266,600	8,995,200
Less: Accumulated Depreciation
Total Accumulated Depreciation	(2,102,300)	(2,041,900)
Property, Plant and Equipment, Net	7,164,300	6,953,300
Construction Work in Progress	288,900	203,500
Net Plant	7,453,200	7,156,809
NSTAR Electric Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	5,309,200	5,100,500
Transmission - Electric	2,211,700	2,131,300
Generation	0	0
Property, Plant and Equipment, Gross	7,520,900	7,231,800
Less: Accumulated Depreciation
Total Accumulated Depreciation	(1,996,800)	(1,886,800)
Property, Plant and Equipment, Net	5,524,100	5,345,000
Construction Work in Progress	351,800	310,500
Net Plant	5,875,874	5,655,458
Public Service Company Of New Hampshire [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	1,918,300	1,804,800
Transmission - Electric	1,005,500	928,200
Generation	1,182,900	1,158,100
Property, Plant and Equipment, Gross	4,106,700	3,891,100
Less: Accumulated Depreciation
Total Accumulated Depreciation	(1,243,800)	(1,171,000)
Property, Plant and Equipment, Net	2,862,900	2,720,100
Construction Work in Progress	110,200	135,300
Net Plant	2,973,057	2,855,363
Western Massachusetts Electric Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	834,600	812,300
Transmission - Electric	1,014,900	964,900
Generation	36,000	36,000
Property, Plant and Equipment, Gross	1,885,500	1,813,200
Less: Accumulated Depreciation
Total Accumulated Depreciation	(330,600)	(307,000)
Property, Plant and Equipment, Net	1,554,900	1,506,200
Construction Work in Progress	88,400	69,100
Net Plant	$ 1,643,335	$ 1,575,306

DERIVATIVE INSTRUMENTS - Gross

DERIVATIVE INSTRUMENTS - Gross Fair Value of Contracts (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	$ 2.6	$ 0
Netting	(0.2)	0
Net Amount Recorded as a Derivative	2.4	0
Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	15.7	16.7
Netting	(10.4)	(10.9)
Net Amount Recorded as a Derivative	5.3	5.8
Prepaid Expenses and Other Current Assets [Member] | The Connecticut Light And Power Company [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	15.3	16.7
Netting	(10.4)	(10.9)
Net Amount Recorded as a Derivative	4.9	5.8
Prepaid Expenses and Other Current Assets [Member] | NSTAR Electric Company [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	0.4	0
Netting	0	0
Net Amount Recorded as a Derivative	0.4	0
Other Noncurrent Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	0	0.1
Netting	0	0
Net Amount Recorded as a Derivative	0	0.1
Other Noncurrent Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	79.3	62
Netting	(13.8)	(19.3)
Net Amount Recorded as a Derivative	65.5	42.7
Other Noncurrent Assets [Member] | The Connecticut Light And Power Company [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	79.3	60.7
Netting	(13.8)	(19.3)
Net Amount Recorded as a Derivative	65.5	41.4
Other Noncurrent Assets [Member] | NSTAR Electric Company [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	0	1.3
Netting	0	0
Net Amount Recorded as a Derivative	0	1.3
Other Current Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	0	(5.8)
Netting	0	0
Net Amount Recorded as a Derivative	0	(5.8)
Other Current Liabilities [Member] | Fair Value, Inputs, Level 3 [Member]
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(87.1)	(92.3)
Netting	0	0
Net Amount Recorded as a Derivative	(87.1)	(92.3)
Other Current Liabilities [Member] | The Connecticut Light And Power Company [Member] | Fair Value, Inputs, Level 3 [Member]
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(85.3)	(91.8)
Netting	0	0
Net Amount Recorded as a Derivative	(85.3)	(91.8)
Other Current Liabilities [Member] | NSTAR Electric Company [Member] | Fair Value, Inputs, Level 3 [Member]
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(1.8)	(0.5)
Netting	0	0
Net Amount Recorded as a Derivative	(1.8)	(0.5)
Derivative Liabilities Non Current [Member] | Fair Value, Inputs, Level 3 [Member]
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(427.4)	(337.1)
Netting	0	0
Net Amount Recorded as a Derivative	(427.4)	(337.1)
Derivative Liabilities Non Current [Member] | The Connecticut Light And Power Company [Member] | Fair Value, Inputs, Level 3 [Member]
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(426.1)	(336.2)
Netting	0	0
Net Amount Recorded as a Derivative	(426.1)	(336.2)
Derivative Liabilities Non Current [Member] | NSTAR Electric Company [Member] | Fair Value, Inputs, Level 3 [Member]
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(1.3)	(0.9)
Netting	0	0
Net Amount Recorded as a Derivative	$ (1.3)	$ (0.9)

DERIVATIVE INSTRUMENTS - Deriva

DERIVATIVE INSTRUMENTS - Derivative Contracts at Fair Value (Details) MWh in Millions, MMBTU in Millions, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)MMBTUMWhMW	Sep. 30, 2015USD ($)	Dec. 31, 2015MMBTU
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of costs or benefits borne under capacity-related contracts by United Illuminated Company			20.00%
Amount of power to be purchased under capacity-related contract (up to) | MW			787
Amount of natural gas to be purchased under futures contracts | MMBTU			10.2		9.1
Losses deferred as regulatory costs | $	$ (53.4)	$ (8.8)	$ (127.8)	$ (58.9)
The Connecticut Light And Power Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of costs or benefits borne under capacity-related contracts			80.00%
Amount of energy to be purchased under renewable energy contract (in mwh) | MWh			0.1
NSTAR Electric Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of power to be purchased under capacity-related contract (up to) | MW			35
Amount of energy to be purchased under renewable energy contract (in mwh) | MWh			0.1

DERIVATIVE INSTRUMENTS - Unobse

DERIVATIVE INSTRUMENTS - Unobservable Inputs Utilized (Details) - Fair Value, Inputs, Level 3 [Member] - $ / KWmo	Sep. 30, 2016	Dec. 31, 2015
Minimum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Capacity Prices (in USDPerKiloWattMonth)	5.50	10.81
Maximum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Capacity Prices (in USDPerKiloWattMonth)	9.75	15.82
The Connecticut Light And Power Company [Member] | Minimum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Capacity Prices (in USDPerKiloWattMonth)	5.50	10.81
The Connecticut Light And Power Company [Member] | Maximum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Capacity Prices (in USDPerKiloWattMonth)	9.75	12.60
Eversource and The Connecticut Light And Power Company [Member] | Minimum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Forward Reserve (in USDPerKiloWattMonth)	1.40	2
Eversource and The Connecticut Light And Power Company [Member] | Maximum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Forward Reserve (in USDPerKiloWattMonth)	2	2
Eversource and NSTAR Electric Company [Member] | Minimum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
REC Prices (in USDPerKiloWattMonth)	29	45
Eversource and NSTAR Electric Company [Member] | Maximum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
REC Prices (in USDPerKiloWattMonth)	37	51

DERIVATIVE INSTRUMENTS - Unob48

DERIVATIVE INSTRUMENTS - Unobservable Inputs Narrative (Details) - Fair Value, Inputs, Level 3 [Member]	9 Months Ended
	Sep. 30, 2016
Minimum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts	4.00%
Maximum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts	21.00%

DERIVATIVE INSTRUMENTS - Deri49

DERIVATIVE INSTRUMENTS - Derivative Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivatives, Net [Rollforward]
Fair Value as of Beginning of Period	$ (412.6)	$ (422.4)	$ (380.9)	$ (415.4)
Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets and Liabilities	(52.3)	(6)	(128.9)	(55.3)
Settlements	21.2	21.4	66.1	63.7
Fair Value as of End of Period	(443.7)	(407)	(443.7)	(407)
The Connecticut Light And Power Company [Member]
Derivatives, Net [Rollforward]
Fair Value as of Beginning of Period	(411.3)	(420.2)	(380.8)	(410.9)
Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets and Liabilities	(49.8)	(7.6)	(122)	(56.6)
Settlements	20.1	20.9	61.8	60.6
Fair Value as of End of Period	(441)	(406.9)	(441)	(406.9)
NSTAR Electric Company [Member]
Derivatives, Net [Rollforward]
Fair Value as of Beginning of Period	(1.3)	(2.2)	(0.1)	(4.5)
Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets and Liabilities	(2.5)	1.6	(6.9)	1.3
Settlements	1.1	0.5	4.3	3.1
Fair Value as of End of Period	$ (2.7)	$ (0.1)	$ (2.7)	$ (0.1)

MARKETABLE SECURITIES - Trading

MARKETABLE SECURITIES - Trading Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Net gains (losses) on trading securities	$ 0.1	$ (0.5)	$ 0.6	$ 1.6
Fair Value, Inputs, Level 1 [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities classified as level 1	$ 10.3		$ 10.3		$ 14.2

MARKETABLE SECURITIES - Schedul

MARKETABLE SECURITIES - Schedule of Available for Sale Securities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 261.2	$ 256.5
Pre-Tax Unrealized Gains	10.7	4.5
Pre-Tax Unrealized Losses	0	(0.6)
Fair Value	271.9	260.4
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	206.7	215.3
Pre-Tax Unrealized Gains	63.7	59.2
Pre-Tax Unrealized Losses	(1)	(3.4)
Fair Value	$ 269.4	$ 271.1

MARKETABLE SECURITIES - Availab

MARKETABLE SECURITIES - Available for Sale Securities Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Debt, equity and marketable securities held in nuclear decommissioning trust	$ 446.9	$ 436.9

MARKETABLE SECURITIES - Sched53

MARKETABLE SECURITIES - Schedule of Contractual Maturities (Details) $ in Millions	Sep. 30, 2016USD ($)
Amortized Cost
Less than one year	$ 29.3
One to five years	58
Six to ten years	47
Greater than ten years	126.9
Total Debt Securities	261.2
Fair Value
Less than one year	29.1
One to five years	59.1
Six to ten years	49.5
Greater than ten years	134.2
Total Debt Securities	$ 271.9

MARKETABLE SECURITIES - Sched54

MARKETABLE SECURITIES - Schedule of Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	$ 551.6	$ 545.7
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	304.2	312.2
Fair Value, Inputs, Level 1 [Member] | Mutual Funds and Equities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	279.7	285.3
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	24.5	26.9
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	247.4	233.5
Fair Value, Inputs, Level 2 [Member] | U.S. Government Issued Debt Securities (Agency and Treasury) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	65.5	46.6
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	43.3	43.9
Fair Value, Inputs, Level 2 [Member] | Asset-Backed Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	18	20
Fair Value, Inputs, Level 2 [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	110.3	111.4
Fair Value, Inputs, Level 2 [Member] | Other Fixed Income Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities recorded at fair value on a recurring basis	$ 10.3	$ 11.6

SHORT-TERM AND LONG-TERM DEBT -

SHORT-TERM AND LONG-TERM DEBT - Commercial Paper Programs and Credit Agreements (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Eversource Parent [Member]
Line of Credit Facility [Line Items]
Amount outstanding during period	$ 0	$ 0
Eversource Parent [Member] | Commercial Paper [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	1,450,000,000
Short-term borrowings outstanding	698,500,000	1,100,000,000
Remaining borrowing capacity	$ 751,500,000	$ 351,500,000
Weighted average interest rate (as a percentage)	0.66%	0.72%
Eversource Parent [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 1,450,000,000
Debt instrument term	5 years
The Connecticut Light And Power Company [Member]
Line of Credit Facility [Line Items]
Notes payable to Eversource Parent	$ 108,500,000	$ 277,400,000
Public Service Company Of New Hampshire [Member]
Line of Credit Facility [Line Items]
Notes payable to Eversource Parent	107,500,000	231,300,000
Western Massachusetts Electric Company [Member]
Line of Credit Facility [Line Items]
Notes payable to Eversource Parent	48,200,000	143,400,000
NSTAR Electric Company [Member]
Line of Credit Facility [Line Items]
Amount outstanding during period	0	0
NSTAR Electric Company [Member] | Commercial Paper [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	450,000,000
Short-term borrowings outstanding	36,000,000	62,500,000
Remaining borrowing capacity	$ 414,000,000	$ 387,500,000
Weighted average interest rate (as a percentage)	0.42%	0.40%
NSTAR Electric Company [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 450,000,000
Debt instrument term	5 years

SHORT-TERM AND LONG-TERM DEBT56

SHORT-TERM AND LONG-TERM DEBT - Short-Term Borrowing Limits (Details) - NSTAR Electric Company [Member] - USD ($)	Sep. 30, 2016	Aug. 08, 2016
Line of Credit Facility [Line Items]
Short-term borrowing limit approved by regulatory agency		$ 655,000,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 450,000,000

SHORT-TERM AND LONG-TERM DEBT57

SHORT-TERM AND LONG-TERM DEBT - Long-Term Debt Issuances (Details) - USD ($)	Jun. 30, 2016	May 31, 2016	Mar. 31, 2016
Eversource Parent [Member] | Senior Notes [Member] | Series I Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 250,000,000
Interest rate stated percentage			2.50%
Eversource Parent [Member] | Senior Notes [Member] | Series J Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 250,000,000
Interest rate stated percentage			3.35%
NSTAR Electric Company [Member] | Unsecured Debt [Member] | Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 250,000,000
Interest rate stated percentage		2.70%
Western Massachusetts Electric Company [Member] | Senior Notes [Member] | Series H Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 50,000,000
Interest rate stated percentage	2.75%

SHORT-TERM AND LONG-TERM DEBT58

SHORT-TERM AND LONG-TERM DEBT - Long-Term Debt Repayments (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	May 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Repayments of debt		$ 200,000	$ 216,700
NSTAR Electric Company [Member]
Debt Instrument [Line Items]
Repayments of debt		$ 200,000	$ 4,700
Unsecured Debt [Member] | NSTAR Electric Company [Member]
Debt Instrument [Line Items]
Repayments of debt	$ 200,000

PENSION BENEFITS AND POSTRETI59

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSIONS - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2016	Aug. 31, 2016
Pension and SERP [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Service cost discount rate under spot rate		4.89%
Interest cost discount rate under spot rate methodology		3.80%
Impact of change in accounting estimate spot rate discount rate	$ 11.5	$ 35
Other Postretirement Benefit Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Service cost discount rate under spot rate		4.09%
Interest cost discount rate under spot rate methodology		2.88%
Impact of change in accounting estimate spot rate discount rate	$ 2.5	$ 7.5
Discount rate used to remeasure benefit obligation				3.62%
Gross impact of plan amendment on accumulated losses				$ 244
Actuarial Loss				142
Effect of plan amendment on accumulated benefit obligation				102
Effect of plan amendment on regulatory assets				106
Effect of plan amendment on accumulated other comprehensive income				$ 4
Subsequent Event [Member] | Other Postretirement Benefit Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Impact on annual PBOP expense			$ (10)

PENSION BENEFITS AND POSTRETI60

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSIONS - Components of Periodic Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amounts included in other deferred benefits		$ 0.8		$ 2.4
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	$ 18.6	22.7	$ 56.6	68.7
Interest Cost	46.4	56.9	139.2	170.3
Expected Return on Plan Assets	(79.4)	(83.9)	(238.5)	(252.1)
Actuarial Loss	31.4	36.5	94.2	111.9
Prior Service Cost/(Credit)	0.9	0.9	2.6	2.7
Total Net Periodic Benefit Expense/(Income)	17.9	33.1	54.1	101.5
Capitalized PBOP Expense/(Income)	5.4	9.8	16.8	31.3
Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	3	4.1	9.2	10.3
Interest Cost	7.5	11.8	26.5	30.4
Expected Return on Plan Assets	(15.9)	(16.9)	(47.3)	(43.2)
Actuarial Loss	3	1.7	5	4.5
Prior Service Cost/(Credit)	(3.6)	(0.1)	(3.7)	(0.3)
Total Net Periodic Benefit Expense/(Income)	(6)	0.6	(10.3)	1.7
Capitalized PBOP Expense/(Income)	(2.6)	0	(4.6)	0.1
The Connecticut Light And Power Company [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	4.6	6.2	14.3	18.4
Interest Cost	10.2	12.9	31.2	38.4
Expected Return on Plan Assets	(18)	(19.8)	(54.2)	(59.1)
Actuarial Loss	6.3	8	19.2	24.2
Prior Service Cost/(Credit)	0.4	0.4	1.1	1.1
Total Net Periodic Benefit Expense/(Income)	3.5	7.7	11.6	23
Intercompany Allocations	3.5	5.8	10.3	18
Capitalized PBOP Expense/(Income)	2.2	4.7	7.1	14.1
The Connecticut Light And Power Company [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.6	0.5	1.4	1.6
Interest Cost	1.3	1.8	4	5.4
Expected Return on Plan Assets	(2.5)	(2.8)	(7.6)	(8.3)
Actuarial Loss	0.5	0.2	0.9	0.5
Prior Service Cost/(Credit)	0.2	0	0.2	0
Total Net Periodic Benefit Expense/(Income)	0.1	(0.3)	(1.1)	(0.8)
Intercompany Allocations	0	0.4	0.3	1.4
Capitalized PBOP Expense/(Income)	0	(0.1)	(0.5)	(0.2)
NSTAR Electric Company [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	3.3	3.7	9.9	11.2
Interest Cost	8.5	10	25.3	30.2
Expected Return on Plan Assets	(16.9)	(17.5)	(50.7)	(52.5)
Actuarial Loss	8.7	8.7	25.8	27
Prior Service Cost/(Credit)	0	0	0	0.1
Total Net Periodic Benefit Expense/(Income)	3.6	4.9	10.3	16
Intercompany Allocations	2.2	3.4	6.7	10.3
Capitalized PBOP Expense/(Income)	2	2.7	5.7	8.6
NSTAR Electric Company [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.6	1.3	2.5	4
Interest Cost	2.5	4.8	10.3	14.2
Expected Return on Plan Assets	(6.4)	(6.8)	(19.2)	(20.5)
Actuarial Loss	1.2	0.6	1.7	1.8
Prior Service Cost/(Credit)	(2.9)	(0.1)	(2.9)	(0.1)
Total Net Periodic Benefit Expense/(Income)	(5)	(0.2)	(7.6)	(0.6)
Intercompany Allocations	(0.1)	0.2	0	0.7
Capitalized PBOP Expense/(Income)	(2.2)	0	(3.3)	(0.1)
Public Service Company Of New Hampshire [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	2.5	3.1	7.5	9
Interest Cost	5.1	6.1	15.4	18.1
Expected Return on Plan Assets	(9.6)	(10.1)	(28.9)	(30.3)
Actuarial Loss	2.5	2.9	7.5	8.8
Prior Service Cost/(Credit)	0.1	0.1	0.3	0.4
Total Net Periodic Benefit Expense/(Income)	0.6	2.1	1.8	6
Intercompany Allocations	1	1.6	3	5
Capitalized PBOP Expense/(Income)	0.4	0.8	1	2.6
Public Service Company Of New Hampshire [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.4	0.3	0.9	1
Interest Cost	0.7	1	2.2	2.9
Expected Return on Plan Assets	(1.4)	(1.5)	(4.2)	(4.4)
Actuarial Loss	0.2	0.1	0.5	0.4
Prior Service Cost/(Credit)	0.1	0	0.1	0
Total Net Periodic Benefit Expense/(Income)	0	(0.1)	(0.5)	(0.1)
Intercompany Allocations	0	0.1	0	0.3
Capitalized PBOP Expense/(Income)	0	0.1	0	0.2
Western Massachusetts Electric Company [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.8	1	2.4	3.2
Interest Cost	2.1	2.6	6.3	7.8
Expected Return on Plan Assets	(4.4)	(4.7)	(13.1)	(14.2)
Actuarial Loss	1.3	1.6	4.1	4.8
Prior Service Cost/(Credit)	0.1	0.1	0.2	0.2
Total Net Periodic Benefit Expense/(Income)	(0.1)	0.6	(0.1)	1.8
Intercompany Allocations	0.6	1.1	1.9	3.3
Capitalized PBOP Expense/(Income)	0.1	0.5	0.3	1.4
Western Massachusetts Electric Company [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.1	0.1	0.3	0.3
Interest Cost	0.3	0.3	0.8	1.1
Expected Return on Plan Assets	(0.6)	(0.6)	(1.7)	(1.9)
Actuarial Loss	0	0	0	0
Prior Service Cost/(Credit)	0	0	0	0
Total Net Periodic Benefit Expense/(Income)	(0.2)	(0.2)	(0.6)	(0.5)
Intercompany Allocations	0	0.1	0	0.3
Capitalized PBOP Expense/(Income)	$ (0.1)	$ 0	$ (0.3)	$ (0.1)

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Schedule of Environmental Matters (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016USD ($)site	Dec. 31, 2015USD ($)site
Site Contingency [Line Items]
Number of Sites | site	63	64
Reserve | $	$ 59.7	$ 51.1
The Connecticut Light And Power Company [Member]
Site Contingency [Line Items]
Number of Sites | site	14	14
Reserve | $	$ 4.7	$ 4.6
NSTAR Electric Company [Member]
Site Contingency [Line Items]
Number of Sites | site	14	15
Reserve | $	$ 2.3	$ 2.4
Public Service Company Of New Hampshire [Member]
Site Contingency [Line Items]
Number of Sites | site	12	12
Reserve | $	$ 4.3	$ 4.5
Western Massachusetts Electric Company [Member]
Site Contingency [Line Items]
Number of Sites | site	4	4
Reserve | $	$ 0.7	$ 0.6

COMMITMENTS AND CONTINGENCIES62

COMMITMENTS AND CONTINGENCIES - Environmental Matters Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Site Contingency [Line Items]
Reserve	$ 59.7	$ 51.1
MGP Site accrual [Member]
Site Contingency [Line Items]
Reserve	$ 53.9	$ 45.5

COMMITMENTS AND CONTINGENCIES63

COMMITMENTS AND CONTINGENCIES - Guarantees and Indemnifications Narrative (Details) $ in Millions	Sep. 30, 2016USD ($)
Access Northeast [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure (up to)	$ 206
Guarantee Of Financial Obligations Of Npt [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure (up to)	25
Guarantee Of Npt Letters Of Credit [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure (up to)	$ 14

COMMITMENTS AND CONTINGENCIES64

COMMITMENTS AND CONTINGENCIES - Schedule of Guarantees and Indemnifications (Details) $ in Millions	Sep. 30, 2016USD ($)
Access Northeast Project Capital Contributions Guarantee Expiring In 2021 [Member]
Loss Contingencies [Line Items]
Maximum Exposure	$ 186.5
Various Subsidiary Surety Bonds And Performance Guarantees Expiring Between 2016 And 2018 [Member]
Loss Contingencies [Line Items]
Maximum Exposure	37.1
Guarantee Of Rocky River Reality And Nusco Lease Payments For Real Estate And Vehicles Expiring 2019 Through 2024 [Member]
Loss Contingencies [Line Items]
Maximum Exposure	$ 9.8

COMMITMENTS AND CONTINGENCIES65

COMMITMENTS AND CONTINGENCIES - Nuclear Fuel Litigation (Details) - USD ($) $ in Millions	Mar. 25, 2016	Sep. 30, 2016
CYAPC [Member]
Loss Contingencies [Line Items]
Damages awarded in litigation	$ 32.6
YAEC [Member]
Loss Contingencies [Line Items]
Damages awarded in litigation	19.6
MYAPC [Member]
Loss Contingencies [Line Items]
Damages awarded in litigation	24.6
Expected proceeds from Yankee Companies to be refunded to utility company		$ 57
Yankee Companies [Member]
Loss Contingencies [Line Items]
Damages awarded in litigation	76.8
Damages sought in litigation	$ 77.9
Eversource [Member] | Yankee Companies [Member]
Loss Contingencies [Line Items]
Expected proceeds from Yankee Companies to be refunded to utility company		26
The Connecticut Light And Power Company [Member] | Yankee Companies [Member]
Loss Contingencies [Line Items]
Expected proceeds from Yankee Companies to be refunded to utility company		13.6
NSTAR Electric Company [Member] | Yankee Companies [Member]
Loss Contingencies [Line Items]
Expected proceeds from Yankee Companies to be refunded to utility company		5
Public Service Company Of New Hampshire [Member] | Yankee Companies [Member]
Loss Contingencies [Line Items]
Expected proceeds from Yankee Companies to be refunded to utility company		3.9
Western Massachusetts Electric Company [Member] | Yankee Companies [Member]
Loss Contingencies [Line Items]
Expected proceeds from Yankee Companies to be refunded to utility company		$ 3.6

COMMITMENTS AND CONTINGENCIES66

COMMITMENTS AND CONTINGENCIES - FERC ROE Complaints (Details) - USD ($) $ in Millions	Apr. 29, 2016	Mar. 22, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014	Jul. 31, 2017	Oct. 31, 2015	Mar. 27, 2014
FERC ROE Complaints [Member]
Loss Contingencies [Line Items]
Base ROE percentage challenged by complainants			11.14%
Period of complaint			15 months
Loss Contingency, loss in period				$ 20
FERC ROE First Complaint [Member]
Loss Contingencies [Line Items]
Base ROE percentage of first complaint period					10.57%
FERC ROE First Complaint [Domain]
Loss Contingencies [Line Items]
Maximum percentage cap of ROE for incentive projects					11.74%
FERC ROE Second and Third Complaints [Member]
Loss Contingencies [Line Items]
Base ROE percentage challenged by complainants			11.14%
FERC ROE Second Complaint [Member]
Loss Contingencies [Line Items]
Period of complaint			15 months					15 months
FERC ALJ recommended base ROE percentage		9.59%
Basis point change			10.00%
Loss contingency, estimate of possible earnings impact			$ 3
FERC ROE Third Complaint [Member]
Loss Contingencies [Line Items]
Period of complaint			15 months				15 months
FERC ALJ recommended base ROE percentage		10.90%
Loss contingency, estimate of possible earnings impact			$ 3
FERC ROE Fourth Complaint [Member]
Loss Contingencies [Line Items]
Base ROE percentage challenged by complainants	10.57%
Maximum percentage cap of ROE for incentive projects	11.74%
The Connecticut Light And Power Company [Member] | FERC ROE Complaints [Member]
Loss Contingencies [Line Items]
Loss Contingency, loss in period				12.5
NSTAR Electric Company [Member] | FERC ROE Complaints [Member]
Loss Contingencies [Line Items]
Loss Contingency, loss in period				2.4
Public Service Company Of New Hampshire [Member] | FERC ROE Complaints [Member]
Loss Contingencies [Line Items]
Loss Contingency, loss in period				1
Western Massachusetts Electric Company [Member] | FERC ROE Complaints [Member]
Loss Contingencies [Line Items]
Loss Contingency, loss in period				$ 4.1
Minimum [Member] | FERC ROE Second Complaint [Member]
Loss Contingencies [Line Items]
FERC ALJ recommended zone of reasonableness FERC ROE percentage		7.12%
Potential loss from base ROE percentage			10.57%					10.57%
Minimum [Member] | FERC ROE Third Complaint [Member]
Loss Contingencies [Line Items]
FERC ALJ recommended zone of reasonableness FERC ROE percentage		7.04%
Maximum [Member] | FERC ROE Second Complaint [Member]
Loss Contingencies [Line Items]
FERC ALJ recommended zone of reasonableness FERC ROE percentage		10.42%
Potential loss from base ROE percentage								9.59%
Estimate of after-tax increase to reserve			$ 34
Maximum [Member] | FERC ROE Third Complaint [Member]
Loss Contingencies [Line Items]
FERC ALJ recommended zone of reasonableness FERC ROE percentage		12.19%
Estimate of after-tax decrease to reserve			$ 8
Subsequent Event [Member] | FERC ROE Fourth Complaint [Member]
Loss Contingencies [Line Items]
Period of complaint						15 months

PSNH GENERATION ASSET SALE - Na

PSNH GENERATION ASSET SALE - Narrative (Details) - Electricity Generation Plant, Non-Nuclear [Member] - Public Service Company Of New Hampshire [Member] $ in Millions	Jun. 10, 2015USD ($)senator	Sep. 30, 2015USD ($)
Regulatory Assets [Line Items]
Number of state senators | senator	2
Payments for restructuring | $	$ 5	$ 5

PSNH GENERATION ASSET SALE - PS

PSNH GENERATION ASSET SALE - PSNH Generation Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Regulatory Assets [Line Items]
Gross Plant	$ 26,289,100	$ 25,226,600
Accumulated Depreciation	(6,728,100)	(6,396,700)
Net Plant	20,807,943	19,892,441
Fuel, Materials, Supplies and Allowances	311,051	336,476
Public Service Company Of New Hampshire [Member]
Regulatory Assets [Line Items]
Gross Plant	4,106,700	3,891,100
Accumulated Depreciation	(1,243,800)	(1,171,000)
Net Plant	2,973,057	2,855,363
Fuel, Materials, Supplies and Allowances	160,882	$ 156,868
Electricity Generation Plant, Non-Nuclear [Member] | Public Service Company Of New Hampshire [Member]
Regulatory Assets [Line Items]
Gross Plant	1,191,000
Accumulated Depreciation	(552,100)
Net Plant	638,900
Fuel, Materials, Supplies and Allowances	$ 161,900

FAIR VALUE OF FINANCIAL INSTR69

FAIR VALUE OF FINANCIAL INSTRUMENTS - Carrying Amounts and Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	$ 155,568	$ 155,568
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	9,609,000	9,034,500
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	166,600	157,900
Long-term Debt	10,454,800	9,425,900
The Connecticut Light And Power Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	116,200	116,200
The Connecticut Light And Power Company [Member] | Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	2,765,400	2,763,700
The Connecticut Light And Power Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	122,200	114,900
Long-term Debt	3,216,800	3,031,600
NSTAR Electric Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	43,000	43,000
NSTAR Electric Company [Member] | Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	2,078,000	2,029,800
NSTAR Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	44,400	43,000
Long-term Debt	2,338,800	2,182,400
Public Service Company Of New Hampshire [Member] | Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	0	0
Long-term Debt	1,071,800	1,071,000
Public Service Company Of New Hampshire [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	0	0
Long-term Debt	1,142,900	1,121,200
Western Massachusetts Electric Company [Member] | Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	0	0
Long-term Debt	566,700	517,300
Western Massachusetts Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	0	0
Long-term Debt	$ 616,900	$ 551,800

ACCUMULATED OTHER COMPREHENSI70

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Schedule of Accumulated Other Comprehensive Income (loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance as of Beginning of Period			$ (66,844)
Net OCI	$ (253)	$ (1,513)	1,227	$ 463
Balance as of End of Period	(65,617)		(65,617)
AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance as of Beginning of Period			(66,800)	(74,000)
OCI Before Reclassifications			(3,000)	(4,300)
Amounts Reclassified from AOCI			4,200	4,800
Net OCI			1,200	500
Balance as of End of Period	(65,600)	(73,500)	(65,600)	(73,500)
Qualified Cash Flow Hedging Instruments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance as of Beginning of Period			(10,300)	(12,400)
OCI Before Reclassifications			0	0
Amounts Reclassified from AOCI			1,600	1,500
Net OCI			1,600	1,500
Balance as of End of Period	(8,700)	(10,900)	(8,700)	(10,900)
Unrealized Gains/(Losses) on Marketable Securities [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance as of Beginning of Period			(1,900)	700
OCI Before Reclassifications			2,300	(3,900)
Amounts Reclassified from AOCI			0	0
Net OCI			2,300	(3,900)
Balance as of End of Period	400	(3,200)	400	(3,200)
Defined Benefit Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance as of Beginning of Period			(54,600)	(62,300)
OCI Before Reclassifications			(5,300)	(400)
Amounts Reclassified from AOCI			2,600	3,300
Net OCI			(2,700)	2,900
Balance as of End of Period	$ (57,300)	$ (59,400)	$ (57,300)	$ (59,400)

COMMON SHARES - Schedule of Com

COMMON SHARES - Schedule of Common Shares (Details) - $ / shares	Sep. 30, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Per Share Par Value (in dollars per share)	$ 5	$ 5
Authorized (in shares)	380,000,000	380,000,000
Issued (in shares)	333,878,402	333,862,615
The Connecticut Light And Power Company [Member]
Class of Stock [Line Items]
Per Share Par Value (in dollars per share)	$ 10	$ 10
Authorized (in shares)	24,500,000	24,500,000
Issued (in shares)	6,035,205	6,035,205
NSTAR Electric Company [Member]
Class of Stock [Line Items]
Per Share Par Value (in dollars per share)	$ 1	$ 1
Authorized (in shares)	100,000,000	100,000,000
Issued (in shares)	100	100
Public Service Company Of New Hampshire [Member]
Class of Stock [Line Items]
Per Share Par Value (in dollars per share)	$ 1	$ 1
Authorized (in shares)	100,000,000	100,000,000
Issued (in shares)	301	301
Western Massachusetts Electric Company [Member]
Class of Stock [Line Items]
Per Share Par Value (in dollars per share)	$ 25	$ 25
Authorized (in shares)	1,072,471	1,072,471
Issued (in shares)	434,653	434,653

COMMON SHARES - Narrative (Deta

COMMON SHARES - Narrative (Details) - shares	Sep. 30, 2016	Dec. 31, 2015
Equity [Abstract]
Treasury stock (in shares)	16,671,366	16,671,366
Common stock outstanding (in shares)	317,207,036	317,191,249

COMMON SHAREHOLDERS' EQUITY A73

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Class of Stock [Line Items]
Net income attributable to noncontrolling interests	$ 1,880	$ 1,879	$ 5,639	$ 5,639
Noncontrolling Interest - Preferred Stock of Subsidiaries	155,568		155,568		$ 155,568
The Connecticut Light And Power Company [Member]
Class of Stock [Line Items]
Noncontrolling Interest - Preferred Stock of Subsidiaries	116,200		116,200		116,200
NSTAR Electric Company [Member]
Class of Stock [Line Items]
Noncontrolling Interest - Preferred Stock of Subsidiaries	$ 43,000		$ 43,000		$ 43,000

EARNINGS PER SHARE - Narrative

EARNINGS PER SHARE - Narrative (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Antidilutive share awards excluded from computation (in shares)	0	0	0	0

EARNINGS PER SHARE - Schedule o

EARNINGS PER SHARE - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net Income Attributable to Common Shareholders	$ 265,319	$ 235,920	$ 713,123	$ 696,680
Weighted Average Common Shares Outstanding:
Basic (in shares)	317,787,836	317,452,212	317,696,823	317,296,107
Dilutive Effect (in shares)	789,243	953,057	814,786	1,099,935
Diluted (in shares)	318,577,079	318,405,269	318,511,609	318,396,042
Basic EPS (in dollars per share)	$ 0.83	$ 0.74	$ 2.24	$ 2.20
Diluted EPS (in dollars per share)	$ 0.83	$ 0.74	$ 2.24	$ 2.19

SEGMENT INFORMATION - Narrative

SEGMENT INFORMATION - Narrative (Details)	9 Months Ended
	Sep. 30, 2016segment
The Connecticut Light And Power Company [Member]
Segment Reporting Information [Line Items]
Number of reportable segments	1
NSTAR Electric Company [Member]
Segment Reporting Information [Line Items]
Number of reportable segments	1
Public Service Company Of New Hampshire [Member]
Segment Reporting Information [Line Items]
Number of reportable segments	1
Western Massachusetts Electric Company [Member]
Segment Reporting Information [Line Items]
Number of reportable segments	1

SEGMENT INFORMATION - Schedule

SEGMENT INFORMATION - Schedule of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Operating Revenues	$ 2,039,706	$ 1,933,105	$ 5,862,525	$ 6,263,597
Depreciation and Amortization	(225,200)	(151,000)	(588,000)	(538,000)
Other Operating Expenses	(1,304,600)	(1,312,900)	(3,852,700)	(4,346,900)
Operating Income/(Loss)	509,869	469,238	1,421,827	1,378,728
Interest Expense	(99,865)	(92,534)	(298,568)	(279,635)
Other Income/(Loss), Net	13,641	5,241	23,689	23,866
Net Income Attributable to Common Shareholders	265,319	235,920	713,123	696,680
Cash Flows Used for Investments in Plant			1,359,171	1,177,285
Assets	31,082,337		31,082,337		$ 30,580,309
Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(201,200)	(198,800)	(651,700)	(664,900)
Depreciation and Amortization	500	500	1,600	1,600
Other Operating Expenses	199,500	198,500	650,200	665,200
Operating Income/(Loss)	(1,200)	200	100	1,900
Interest Expense	1,300	1,200	4,800	3,400
Other Income/(Loss), Net	(255,500)	(242,200)	(784,000)	(774,500)
Net Income Attributable to Common Shareholders	(254,700)	(240,800)	(778,400)	(769,200)
Cash Flows Used for Investments in Plant			0	0
Assets	(12,286,800)		(12,286,800)		(11,781,500)
Operating Segments [Member] | Electric Distribution [Member]
Segment Reporting Information [Line Items]
Operating Revenues	1,623,400	1,543,700	4,362,600	4,686,500
Depreciation and Amortization	(154,800)	(84,500)	(380,900)	(342,100)
Other Operating Expenses	(1,146,800)	(1,140,800)	(3,230,100)	(3,535,700)
Operating Income/(Loss)	321,800	318,400	751,600	808,700
Interest Expense	(49,000)	(47,400)	(144,600)	(140,600)
Other Income/(Loss), Net	5,300	1,900	11,600	9,600
Net Income Attributable to Common Shareholders	170,100	167,500	381,300	418,900
Cash Flows Used for Investments in Plant			570,900	506,500
Assets	18,140,000		18,140,000		17,981,300
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Operating Revenues	99,200	106,200	622,300	799,600
Depreciation and Amortization	(15,200)	(17,500)	(47,900)	(53,400)
Other Operating Expenses	(87,800)	(92,700)	(462,400)	(631,500)
Operating Income/(Loss)	(3,800)	(4,000)	112,000	114,700
Interest Expense	(10,200)	(9,200)	(30,800)	(27,200)
Other Income/(Loss), Net	600	(200)	500	(100)
Net Income Attributable to Common Shareholders	(7,000)	(3,700)	51,900	57,300
Cash Flows Used for Investments in Plant			170,300	120,000
Assets	3,149,900		3,149,900		3,104,500
Operating Segments [Member] | Electric Transmission [Member]
Segment Reporting Information [Line Items]
Operating Revenues	306,800	270,400	892,500	787,200
Depreciation and Amortization	(47,100)	(42,400)	(137,700)	(122,600)
Other Operating Expenses	(90,200)	(78,300)	(245,700)	(225,500)
Operating Income/(Loss)	169,500	149,700	509,100	439,100
Interest Expense	(26,900)	(25,900)	(82,200)	(79,800)
Other Income/(Loss), Net	6,300	3,800	14,200	11,900
Net Income Attributable to Common Shareholders	88,400	78,000	266,600	225,000
Cash Flows Used for Investments in Plant			536,200	493,900
Assets	8,454,400		8,454,400		8,019,300
Operating Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	211,500	211,600	636,800	655,200
Depreciation and Amortization	(8,600)	(7,100)	(23,100)	(21,500)
Other Operating Expenses	(179,300)	(199,600)	(564,700)	(619,400)
Operating Income/(Loss)	23,600	4,900	49,000	14,300
Interest Expense	(15,100)	(11,200)	(45,800)	(35,400)
Other Income/(Loss), Net	256,900	241,900	781,400	777,000
Net Income Attributable to Common Shareholders	268,500	$ 234,900	791,700	764,700
Cash Flows Used for Investments in Plant			81,800	$ 56,900
Assets	$ 13,624,800		$ 13,624,800		$ 13,256,700