Eversource Energy (ES) 10-Q 7 May 19 2019 Q1 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document And Entity [Line Items]
Entity Registrant Name	Eversource Energy
Entity Central Index Key	0000072741
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Smaller Reporting Company	false
Trading Symbol	ES
Entity Common Stock, Shares Outstanding (in shares)		317,461,097
The Connecticut Light and Power Company
Document And Entity [Line Items]
Entity Registrant Name	The Connecticut Light and Power Company
Entity Central Index Key	0000023426
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		6,035,205
Public Service Company of New Hampshire
Document And Entity [Line Items]
Entity Registrant Name	Public Service Company of New Hampshire
Entity Central Index Key	0000315256
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		301
NSTAR Electric Company
Document And Entity [Line Items]
Entity Registrant Name	NSTAR Electric Company
Entity Central Index Key	0000013372
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		200

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current Assets:
Cash	$ 35,145	$ 108,068
Receivables, Net	1,140,348	994,055
Unbilled Revenues	159,288	176,285
Fuel, Materials, Supplies and Inventory	277,104	238,042
Regulatory Assets	507,255	514,779
Prepayments and Other Current Assets	181,724	260,995
Total Current Assets	2,300,864	2,292,224
Property, Plant and Equipment, Net	26,032,781	25,610,428
Deferred Debits and Other Assets:
Regulatory Assets	4,589,427	4,631,137
Goodwill	4,427,266	4,427,266
Investments in Unconsolidated Affiliates	711,476	464,286
Marketable Securities	415,405	417,508
Other Long-Term Assets	463,788	398,407
Total Deferred Debits and Other Assets	10,607,362	10,338,604
Total Assets	38,941,007	38,241,256
Current Liabilities:
Notes Payable	1,477,830	910,000
Long-Term Debt – Current Portion	805,519	837,319
Rate Reduction Bonds – Current Portion	43,210	52,332
Accounts Payable	1,006,774	1,119,995
Regulatory Liabilities	385,442	370,230
Other Current Liabilities	840,587	823,006
Total Current Liabilities	4,559,362	4,112,882
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	3,543,052	3,506,030
Regulatory Liabilities	3,627,389	3,609,475
Derivative Liabilities	372,957	379,562
Accrued Pension, SERP and PBOP	939,786	962,510
Other Long-Term Liabilities	1,259,400	1,196,336
Total Deferred Credits and Other Liabilities	9,742,584	9,653,913
Long-Term Debt	12,284,330	12,248,743
Rate Reduction Bonds	561,727	583,331
Noncontrolling Interest – Preferred Stock of Subsidiaries	155,570	155,570
Common Shareholders' Equity:
Common Shares	1,669,392	1,669,392
Capital Surplus, Paid In	6,242,089	6,241,222
Retained Earnings	4,092,895	3,953,974
Accumulated Other Comprehensive Loss	(57,804)	(60,000)
Treasury Stock	(309,138)	(317,771)
Common Stockholder's Equity	11,637,434	11,486,817
Commitments and Contingencies
Total Liabilities and Capitalization	38,941,007	38,241,256
The Connecticut Light and Power Company
Current Assets:
Cash	7,496	87,721
Receivables, Net	443,684	397,026
Accounts Receivable from Affiliated Companies	30,363	23,082
Unbilled Revenues	51,300	56,971
Fuel, Materials, Supplies and Inventory	52,109	44,529
Regulatory Assets	147,712	125,155
Prepaid Property Taxes	41,341	19,555
Prepayments and Other Current Assets	20,384	40,724
Total Current Assets	794,389	794,763
Property, Plant and Equipment, Net	9,065,880	8,909,701
Deferred Debits and Other Assets:
Regulatory Assets	1,496,679	1,505,488
Other Long-Term Assets	197,571	199,767
Total Deferred Debits and Other Assets	1,694,250	1,705,255
Total Assets	11,554,519	11,409,719
Current Liabilities:
Long-Term Debt – Current Portion	0	250,000
Accounts Payable	347,928	324,983
Accounts Payable to Affiliated Companies	94,738	26,452
Obligations to Third Party Suppliers	56,065	56,248
Accrued Taxes	55,693	38,205
Accrued Interest	42,424	38,395
Regulatory Liabilities	106,489	109,614
Derivative Liabilities	59,651	55,058
Other Current Liabilities	71,461	84,488
Total Current Liabilities	834,449	983,443
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,184,425	1,166,784
Regulatory Liabilities	1,126,279	1,122,157
Derivative Liabilities	372,774	379,536
Accrued Pension, SERP and PBOP	279,914	282,771
Other Long-Term Liabilities	165,307	155,495
Total Deferred Credits and Other Liabilities	3,128,699	3,106,743
Long-Term Debt	3,265,756	3,004,016
Noncontrolling Interest – Preferred Stock of Subsidiaries	116,200	116,200
Common Shareholders' Equity:
Common Shares	60,352	60,352
Capital Surplus, Paid In	2,410,765	2,410,765
Retained Earnings	1,737,980	1,727,899
Accumulated Other Comprehensive Loss	318	301
Common Stockholder's Equity	4,209,415	4,199,317
Commitments and Contingencies
Total Liabilities and Capitalization	11,554,519	11,409,719
NSTAR Electric
Current Assets:
Cash	1,769	1,606
Receivables, Net	400,082	361,296
Accounts Receivable from Affiliated Companies	20,097	31,344
Unbilled Revenues	31,698	34,518
Fuel, Materials, Supplies and Inventory	160,221	114,202
Regulatory Assets	234,662	241,747
Prepayments and Other Current Assets	24,643	51,960
Total Current Assets	873,172	836,673
Property, Plant and Equipment, Net	8,915,608	8,794,700
Deferred Debits and Other Assets:
Regulatory Assets	1,173,851	1,196,512
Prepaid PBOP	139,132	132,810
Other Long-Term Assets	134,536	109,764
Total Deferred Debits and Other Assets	1,447,519	1,439,086
Total Assets	11,236,299	11,070,459
Current Liabilities:
Notes Payable	368,430	278,500
Notes Payable to Eversource Parent	22,300	0
Long-Term Debt – Current Portion	95,000	0
Accounts Payable	306,888	384,398
Accounts Payable to Affiliated Companies	115,676	89,636
Obligations to Third Party Suppliers	110,742	109,547
Renewable Portfolio Standards Compliance Obligations	175,391	139,898
Regulatory Liabilities	193,959	190,620
Other Current Liabilities	52,156	74,872
Total Current Liabilities	1,440,542	1,267,471
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,305,518	1,294,467
Regulatory Liabilities	1,514,557	1,513,279
Accrued Pension, SERP and PBOP	5,496	14,145
Other Long-Term Liabilities	293,794	263,096
Total Deferred Credits and Other Liabilities	3,119,365	3,084,987
Long-Term Debt	2,850,196	2,944,846
Noncontrolling Interest – Preferred Stock of Subsidiaries	43,000	43,000
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	1,653,442	1,633,442
Retained Earnings	2,131,015	2,098,091
Accumulated Other Comprehensive Loss	(1,261)	(1,378)
Common Stockholder's Equity	3,783,196	3,730,155
Commitments and Contingencies
Total Liabilities and Capitalization	11,236,299	11,070,459
Public Service Company of New Hampshire
Current Assets:
Cash	3,961	1,439
Receivables, Net	102,806	104,854
Accounts Receivable from Affiliated Companies	11,520	8,444
Unbilled Revenues	43,289	47,145
Taxes Receivable	7,441	25,913
Fuel, Materials, Supplies and Inventory	37,361	37,504
Regulatory Assets	76,599	67,228
Special Deposits	21,059	47,498
Prepayments and Other Current Assets	2,940	17,564
Total Current Assets	306,976	357,589
Property, Plant and Equipment, Net	2,920,560	2,880,073
Deferred Debits and Other Assets:
Regulatory Assets	855,369	862,288
Other Long-Term Assets	29,884	27,406
Total Deferred Debits and Other Assets	885,253	889,694
Total Assets	4,112,789	4,127,356
Current Liabilities:
Notes Payable to Eversource Parent	61,000	57,000
Long-Term Debt – Current Portion	150,000	150,000
Rate Reduction Bonds – Current Portion	43,210	52,332
Accounts Payable	106,398	111,292
Accounts Payable to Affiliated Companies	37,976	26,029
Regulatory Liabilities	45,655	55,526
Other Current Liabilities	55,088	64,046
Total Current Liabilities	499,327	516,225
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	489,434	481,221
Regulatory Liabilities	429,932	428,069
Accrued Pension, SERP and PBOP	122,490	124,457
Other Long-Term Liabilities	37,956	36,339
Total Deferred Credits and Other Liabilities	1,079,812	1,070,086
Long-Term Debt	655,294	655,173
Rate Reduction Bonds	561,727	583,331
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	678,134	678,134
Retained Earnings	641,039	627,258
Accumulated Other Comprehensive Loss	(2,544)	(2,851)
Common Stockholder's Equity	1,316,629	1,302,541
Commitments and Contingencies
Total Liabilities and Capitalization	$ 4,112,789	$ 4,127,356

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Revenues	$ 2,415,792	$ 2,287,962
Operating Expenses:
Purchased Power, Fuel and Transmission	974,882	946,747
Operations and Maintenance	335,597	332,549
Depreciation	214,948	204,266
Amortization	70,961	45,194
Energy Efficiency Programs	140,116	134,241
Taxes Other Than Income Taxes	184,588	182,433
Total Operating Expenses	1,921,092	1,845,430
Operating Income	494,700	442,532
Interest Expense	131,734	121,129
Other Income, Net	30,985	33,789
Income Before Income Tax Expense	393,951	355,192
Income Tax Expense	83,393	83,766
Net Income	310,558	271,426
Net Income Attributable to Noncontrolling Interests	1,880	1,880
Net Income Attributable to Common Shareholders	$ 308,678	$ 269,546
Basic and Diluted Earnings Per Common Share (in dollars per share)	$ 0.97	$ 0.85
Weighted Average Common Shares Outstanding:
Basic (in shares)	317,624,593	317,397,052
Diluted (in shares)	318,316,082	317,992,999
The Connecticut Light and Power Company
Operating Revenues	$ 849,246	$ 784,983
Operating Expenses:
Purchased Power, Fuel and Transmission	319,833	301,889
Operations and Maintenance	130,637	117,292
Depreciation	73,289	67,498
Amortization of Regulatory Assets, Net	35,671	28,006
Energy Efficiency Programs	25,988	22,760
Taxes Other Than Income Taxes	92,000	90,300
Total Operating Expenses	677,418	627,745
Operating Income	171,828	157,238
Interest Expense	35,781	36,823
Other Income, Net	3,880	6,560
Income Before Income Tax Expense	139,927	126,975
Income Tax Expense	29,456	28,407
Net Income	110,471	98,568
NSTAR Electric Company
Operating Revenues	797,612	770,127
Operating Expenses:
Purchased Power, Fuel and Transmission	330,104	332,579
Operations and Maintenance	112,963	118,682
Depreciation	72,584	70,542
Amortization of Regulatory Assets, Net	22,584	6,364
Energy Efficiency Programs	76,729	74,793
Taxes Other Than Income Taxes	44,822	48,186
Total Operating Expenses	659,786	651,146
Operating Income	137,826	118,981
Interest Expense	27,881	26,464
Other Income, Net	11,086	12,601
Income Before Income Tax Expense	121,031	105,118
Income Tax Expense	27,017	27,969
Net Income	94,014	77,149
Public Service Company of New Hampshire
Operating Revenues	276,435	267,350
Operating Expenses:
Purchased Power, Fuel and Transmission	113,531	109,717
Operations and Maintenance	52,630	51,380
Depreciation	22,919	23,493
Amortization	13,667	5,035
Energy Efficiency Programs	6,714	5,157
Taxes Other Than Income Taxes	17,311	16,801
Total Operating Expenses	226,772	211,583
Operating Income	49,663	55,767
Interest Expense	14,367	12,772
Other Income, Net	7,022	4,749
Income Before Income Tax Expense	42,318	47,744
Income Tax Expense	9,537	12,651
Net Income	$ 32,781	$ 35,093

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net Income	$ 310,558	$ 271,426
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	316
Qualified Cash Flow Hedging Instruments		724
Changes in Unrealized Gains/(Losses) on Marketable Securities	655	(444)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	1,225	2,993
Other Comprehensive Income, Net of Tax	2,196	3,273
Comprehensive Income Attributable to Noncontrolling Interests	(1,880)	(1,880)
Comprehensive Income Attributable to Common Shareholders	310,874	272,819
The Connecticut Light and Power Company
Net Income	110,471	98,568
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	(6)
Qualified Cash Flow Hedging Instruments		52
Changes in Unrealized Gains/(Losses) on Marketable Securities	23	(12)
Other Comprehensive Income, Net of Tax	17	40
Comprehensive Income Attributable to Common Shareholders	110,488	98,608
NSTAR Electric Company
Net Income	94,014	77,149
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	110
Qualified Cash Flow Hedging Instruments		109
Changes in Unrealized Gains/(Losses) on Marketable Securities	6	(4)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	1	1
Other Comprehensive Income, Net of Tax	117	106
Comprehensive Income Attributable to Common Shareholders	94,131	77,255
Public Service Company of New Hampshire
Net Income	32,781	35,093
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	269
Qualified Cash Flow Hedging Instruments		290
Changes in Unrealized Gains/(Losses) on Marketable Securities	38	(21)
Other Comprehensive Income, Net of Tax	307	269
Comprehensive Income Attributable to Common Shareholders	$ 33,088	$ 35,362

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Capital Surplus, Paid In	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	The Connecticut Light and Power Company	The Connecticut Light and Power CompanyCommon Shares	The Connecticut Light and Power CompanyCapital Surplus, Paid In	The Connecticut Light and Power CompanyRetained Earnings	The Connecticut Light and Power CompanyAccumulated Other Comprehensive Loss	NSTAR Electric Company	NSTAR Electric CompanyCommon Shares	NSTAR Electric CompanyCapital Surplus, Paid In	NSTAR Electric CompanyRetained Earnings	NSTAR Electric CompanyAccumulated Other Comprehensive Loss	Public Service Company of New Hampshire	Public Service Company of New HampshireCommon Shares	Public Service Company of New HampshireCapital Surplus, Paid In	Public Service Company of New HampshireRetained Earnings	Public Service Company of New HampshireAccumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2017		316,885,808						6,035,205					200					301
Balance at Dec. 31, 2017	$ 11,086,242	$ 1,669,392	$ 6,239,940	$ 3,561,084	$ (66,403)	$ (317,771)	$ 3,587,127	$ 60,352	$ 2,110,765	$ 1,415,741	$ 269	$ 3,446,080	$ 0	$ 1,502,942	$ 1,944,961	$ (1,823)	$ 1,350,594	$ 0	$ 843,134	$ 511,382	$ (3,922)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	271,426			271,426			98,568			98,568		77,149			77,149		35,093			35,093
Dividends on Common Shares	(160,027)			(160,027)			(60,000)			(60,000)		(161,000)			(161,000)
Dividends on Preferred Stock	(1,880)			(1,880)			(1,390)			(1,390)		(490)			(490)
Other												1			1
Long-Term Incentive Plan Activity	(15,320)		(15,320)
Capital Contributions from Eversource Parent							9,000		9,000			92,500		92,500
Other Comprehensive Income	3,273				3,273		40				40	106				106	269				269
Balance (in shares) at Mar. 31, 2018		316,885,808						6,035,205					200					301
Balance at Mar. 31, 2018	$ 11,183,714	$ 1,669,392	6,224,620	3,670,603	(63,130)	(317,771)	3,633,345	$ 60,352	2,119,765	1,452,919	309	3,454,346	$ 0	1,595,442	1,860,621	(1,717)	1,385,956	$ 0	843,134	546,475	(3,653)
Balance (in shares) at Dec. 31, 2018	316,885,808	316,885,808						6,035,205					200					301
Balance at Dec. 31, 2018	$ 11,486,817	$ 1,669,392	6,241,222	3,953,974	(60,000)	(317,771)	4,199,317	$ 60,352	2,410,765	1,727,899	301	3,730,155	$ 0	1,633,442	2,098,091	(1,378)	1,302,541	$ 0	678,134	627,258	(2,851)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	310,558			310,558			110,471			110,471		94,014			94,014		32,781			32,781
Dividends on Common Shares	(169,757)			(169,757)			(99,000)			(99,000)		(60,600)			(60,600)		(19,000)			(19,000)
Dividends on Preferred Stock	(1,880)			(1,880)			(1,390)			(1,390)		(490)			(490)
Long-Term Incentive Plan Activity	(16,609)		(16,609)
Issuance of Treasury Shares (in shares)		461,662
Issuance of Treasury Shares	26,109		17,476			8,633
Capital Contributions from Eversource Parent												20,000		20,000
Other Comprehensive Income	$ 2,196				2,196		17				17	117				117	307				307
Balance (in shares) at Mar. 31, 2019	317,347,470	317,347,470						6,035,205					200					301
Balance at Mar. 31, 2019	$ 11,637,434	$ 1,669,392	$ 6,242,089	$ 4,092,895	$ (57,804)	$ (309,138)	$ 4,209,415	$ 60,352	$ 2,410,765	$ 1,737,980	$ 318	$ 3,783,196	$ 0	$ 1,653,442	$ 2,131,015	$ (1,261)	$ 1,316,629	$ 0	$ 678,134	$ 641,039	$ (2,544)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends on Common Shares (in dollars per share)	$ 0.535	$ 0.505

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Activities:
Net Income	$ 310,558	$ 271,426
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	214,948	204,266
Deferred Income Taxes	18,085	88,481
Uncollectible Expense	18,565	19,613
Pension, SERP and PBOP Expense/(Income), Net	8,428	(1,965)
Pension and PBOP Contributions	(4,700)	(171,244)
Regulatory (Under)/Over Recoveries, Net	(19,232)	70,457
Amortization	70,961	45,194
Other	(37,310)	(74,582)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(155,823)	(156,888)
Fuel, Materials, Supplies and Inventory	(39,063)	(26,956)
Taxes Receivable/Accrued, Net	126,381	(5,061)
Accounts Payable	(13,556)	(61,571)
Other Current Assets and Liabilities, Net	(70,242)	(23,456)
Net Cash Flows Provided by Operating Activities	428,000	177,714
Investing Activities:
Investments in Property, Plant and Equipment	(674,694)	(607,334)
Proceeds from Sales of Marketable Securities	234,497	145,438
Purchases of Marketable Securities	(237,794)	(143,264)
Proceeds from the Sale of Generation Assets	0	130,641
Investments in Unconsolidated Affiliates	(249,138)	(7,340)
Other Investing Activities	4,893	2,140
Net Cash Flows (Used in)/Provided by Investing Activities	(922,236)	(479,719)
Financing Activities:
Cash Dividends on Common Stock	(169,757)	(160,027)
Cash Dividends on Preferred Stock	(1,880)	(1,880)
Issuance of Treasury Shares	26,109	0
Increase in Notes Payable	829,430	(240,005)
Repayment of Rate Reduction Bonds	(30,727)	0
Issuance of Long-Term Debt	0	1,150,000
Retirement of Long-Term Debt	(250,215)	(150,218)
Other Financing Activities	(9,676)	(19,140)
Net Cash Flows Provided by Financing Activities	393,284	578,730
Net (Decrease)/Increase in Cash and Restricted Cash	(100,952)	276,725
Cash and Restricted Cash - Beginning of Period	209,324	85,890
Cash and Restricted Cash - End of Period	108,372	362,615
The Connecticut Light and Power Company
Operating Activities:
Net Income	110,471	98,568
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	73,289	67,498
Deferred Income Taxes	15,188	29,109
Uncollectible Expense	4,116	3,912
Pension, SERP and PBOP Expense/(Income), Net	4,063	3,158
Pension Contributions	0	(82,276)
Regulatory (Under)/Over Recoveries, Net	(54,671)	(8,878)
Amortization of Regulatory Assets, Net	35,671	28,006
Other	(5,848)	(18,940)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(60,506)	(46,330)
Taxes Receivable/Accrued, Net	41,399	42,460
Accounts Payable	75,373	(28,408)
Other Current Assets and Liabilities, Net	(40,274)	(23,160)
Net Cash Flows Provided by Operating Activities	198,271	64,719
Investing Activities:
Investments in Property, Plant and Equipment	(189,423)	(202,126)
Other Investing Activities	59	56
Net Cash Flows (Used in)/Provided by Investing Activities	(189,364)	(202,070)
Financing Activities:
Cash Dividends on Common Stock	(99,000)	(60,000)
Cash Dividends on Preferred Stock	(1,390)	(1,390)
Capital Contributions from Eversource Parent	0	9,000
Increase in Notes Payable to Eversource Parent	261,600	(69,500)
Issuance of Long-Term Debt	0	500,000
Retirement of Long-Term Debt	(250,000)	0
Other Financing Activities	(326)	(6,539)
Net Cash Flows Provided by Financing Activities	(89,116)	371,571
Net (Decrease)/Increase in Cash and Restricted Cash	(80,209)	234,220
Cash and Restricted Cash - Beginning of Period	91,613	9,619
Cash and Restricted Cash - End of Period	11,404	243,839
NSTAR Electric Company
Operating Activities:
Net Income	94,014	77,149
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	72,584	70,542
Deferred Income Taxes	3,722	22,542
Uncollectible Expense	5,953	7,526
Pension, SERP and PBOP Income, Net	(4,279)	(9,295)
Pension and PBOP Contributions	(1,503)	0
Regulatory (Under)/Over Recoveries, Net	4,329	17,618
Amortization of Regulatory Assets, Net	22,584	6,364
Other	(8,043)	(9,730)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(29,220)	(52,949)
Fuel, Materials, Supplies and Inventory	(46,020)	(37,427)
Taxes Receivable/Accrued, Net	29,483	(22,698)
Accounts Payable	(18,109)	43,170
Other Current Assets and Liabilities, Net	11,466	23,703
Net Cash Flows Provided by Operating Activities	136,961	136,515
Investing Activities:
Investments in Property, Plant and Equipment	(208,540)	(192,036)
Other Investing Activities	17	(654)
Net Cash Flows (Used in)/Provided by Investing Activities	(208,523)	(192,690)
Financing Activities:
Cash Dividends on Common Stock	(60,600)	(161,000)
Cash Dividends on Preferred Stock	(490)	(490)
Capital Contributions from Eversource Parent	20,000	92,500
Increase in Notes Payable to Eversource Parent	22,300	0
Increase in Notes Payable	89,930	133,000
Other Financing Activities	668	(78)
Net Cash Flows Provided by Financing Activities	71,808	63,932
Net (Decrease)/Increase in Cash and Restricted Cash	246	7,757
Cash and Restricted Cash - Beginning of Period	14,659	14,708
Cash and Restricted Cash - End of Period	14,905	22,465
Public Service Company of New Hampshire
Operating Activities:
Net Income	32,781	35,093
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	22,919	23,493
Deferred Income Taxes	6,541	43,021
Uncollectible Expense	1,700	1,700
Regulatory (Under)/Over Recoveries, Net	(26,986)	129
Amortization	13,667	5,035
Other	104	(15,212)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	1,103	(80)
Fuel, Materials, Supplies and Inventory	144	4,854
Taxes Receivable/Accrued, Net	17,572	(5,867)
Accounts Payable	58,327	(18,760)
Other Current Assets and Liabilities, Net	6,472	24,543
Net Cash Flows Provided by Operating Activities	132,644	96,249
Investing Activities:
Investments in Property, Plant and Equipment	(110,926)	(72,287)
Proceeds from the Sale of Generation Assets	0	130,641
Other Investing Activities	102	97
Net Cash Flows (Used in)/Provided by Investing Activities	(110,824)	58,451
Financing Activities:
Cash Dividends on Common Stock	(19,000)	(150,000)
Increase in Notes Payable to Eversource Parent	4,000	8,400
Repayment of Rate Reduction Bonds	(30,727)	0
Other Financing Activities	(20)	(38)
Net Cash Flows Provided by Financing Activities	(45,747)	(141,638)
Net (Decrease)/Increase in Cash and Restricted Cash	(23,927)	13,062
Cash and Restricted Cash - Beginning of Period	52,723	2,191
Cash and Restricted Cash - End of Period	$ 28,796	$ 15,253

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2019
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 and PSNH (electric utilities), Yankee Gas and NSTAR Gas (natural gas utilities) and Aquarion (water utilities). Eversource provides energy delivery and/or water service to approximately four million electric, natural gas and water customers through eight 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 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 2018 Form 10-K, which was filed with the SEC on February 26, 2019. 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 and PSNH's financial position as of March 31, 2019 and December 31, 2018 , and the results of operations, comprehensive income, common shareholders' equity, and cash flows for the three months ended March 31, 2019 and 2018 . The results of operations, comprehensive income, and cash flows for the three months ended March 31, 2019 and 2018 are not necessarily indicative of the results expected for a full year. Eversource consolidates CYAPC and YAEC because CL&P's, NSTAR Electric's and PSNH's combined ownership and voting interests in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements. Eversource's utility subsidiaries' electric, natural gas and water distribution 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. B. Accounting Standards Accounting Standards Issued but Not Yet Effective: In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses. Under the new guidance, immediate recognition of all credit losses expected over the life of a financial instrument is required. The new standard also revises the other-than-temporary impairment model for available-for-sale debt securities . The standard is effective January 1, 2020, and requires a modified retrospective transition approach through a cumulative-effect adjustment to retained earnings. The Company is assessing the impacts of this standard on the accounting for credit losses on its financial instruments, including accounts receivable. Accounting Standards Recently Adopted: On January 1, 2019, the Company adopted ASU 2016-02, Leases (Topic 842), which amended existing lease accounting guidance. The Company applied the Topic 842 lease criteria to new leases and lease renewals entered into effective on or after January 1, 2019. The ASU required balance sheet recognition of leases deemed to be operating leases as well as additional disclosure requirements. The recognition, measurement and presentation of expenses and cash flows were not significantly changed. The Company also adopted the modified retrospective transition method allowed in ASU 2018-11, Leases (Topic 842) - Targeted Improvements , which allowed the Company to adopt the new leases standard as of January 1, 2019, with prior periods presented in the financial statements continuing to follow existing lease accounting guidance under Topic 840 (Leases) in the accounting literature. Implementation of ASU 2018-11 had no effect on retained earnings, and the requirements of the new lease standard (Topic 842) are reflected in the 2019 financial statements and footnotes. The Company elected the practical expedient package whereby it did not need to reassess whether or not an existing contract is or contains a lease or whether a lease is an operating or capital lease, and it did not need to reassess initial direct costs for leases. Election of this practical expedient allowed us to carry forward our historical lease classifications. The Company elected the practical expedient to not reevaluate land easements existing at adoption if they were not previously accounted for as leases. The Company also elected to use the discount rate as of the January 1, 2019 implementation date to discount its operating lease liabilities. The Company did not elect the hindsight practical expedient to determine the lease term for existing leases. The Company determined the impact the ASUs had on its financial statements by reviewing its lease population and identifying lease data needed for the disclosure requirements. The Company implemented a new lease accounting system in 2019 to ensure ongoing compliance with the ASU’s requirements. Adoption of the new standard resulted in the recording of operating lease liabilities and right-of-use assets on the balance sheet upon transition at January 1, 2019 of $58.0 million at Eversource, $25.3 million at NSTAR Electric, $0.6 million at CL&P, and $0.6 million at PSNH. Implementation of the new guidance did not have an impact on each company’s results of operations or cash flows. C. Northern Pass Northern Pass is Eversource's planned 1,090 MW HVDC transmission line that will interconnect from the Québec-New Hampshire border to Franklin, New Hampshire and an associated alternating current radial transmission line between Franklin and Deerfield, New Hampshire. As of March 31, 2019 , our capitalized Northern Pass project costs were approximately $311 million . On January 25, 2018, Northern Pass was selected as the winning bidder in the Massachusetts Clean Energy Request for Proposals ("RFP"). In March 2018, the New Hampshire Site Evaluation Committee ("NHSEC") issued a written decision denying Northern Pass’ siting application after which the Massachusetts EDCs revoked the selection of, and terminated contract negotiations with, Northern Pass under the Massachusetts Clean Energy RFP. On July 12, 2018, the NHSEC issued a written decision denying Northern Pass’ April 2018 motion for rehearing. On October 12, 2018, the New Hampshire Supreme Court accepted an appeal filed by NPT, which alleged that the NHSEC failed to follow applicable law in its review of the project. Subsequently, the NHSEC transmitted the record of its proceedings to the New Hampshire Supreme Court on December 11, 2018. Briefing of the appeal began on February 4, 2019 and concluded on April 10, 2019. The New Hampshire Supreme Court will hear oral arguments on May 15, 2019 and a decision is expected later this year. NPT intends to continue to pursue NHSEC approval to construct the project. Consistent with Eversource’s and HQ’s long-term relationship to bring clean energy into New England, Eversource and HQ remain committed to Northern Pass and the many benefits this project will bring to our customers and the region. We continue to believe that our project costs are recoverable based on our expectation that the Northern Pass project remains probable of being placed in service. If, as a result of future events and changes in circumstances, a future recoverability review were to conclude that our project costs are not recoverable, then we would reduce Northern Pass' project costs to the estimated fair value, which could result in most of our $311 million of capitalized project costs being impaired. Such an impairment could have a material adverse effect on our financial position and results of operations. D. Provision for Uncollectible Accounts Eversource, including CL&P, NSTAR Electric and PSNH, 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 NSTAR Electric and NSTAR Gas to recover in rates, amounts associated with certain uncollectible hardship accounts receivable. These uncollectible hardship customer account balances are included in Regulatory Assets or Other Long-Term Assets on the balance sheets. The total provision for uncollectible accounts is included in Receivables, Net on the balance sheets. The provision for uncollectible hardship accounts is included in the total uncollectible provision balance. The provision balances are as follows: Total Provision for Uncollectible Accounts Provision for Uncollectible Hardship Accounts (Millions of Dollars) As of March 31, 2019 As of December 31, 2018 As of March 31, 2019 As of December 31, 2018 Eversource $ 223.3 $ 212.7 $ 134.6 $ 131.5 CL&P 93.0 88.0 75.2 71.9 NSTAR Electric 74.8 74.5 40.9 42.5 PSNH 11.0 11.1 — — Uncollectible expense associated with customers' accounts receivable included in Operations and Maintenance expense on the statements of income is as follows: For the Three Months Ended (Millions of Dollars) March 31, 2019 March 31, 2018 Eversource $ 18.6 $ 19.6 CL&P 4.1 3.9 NSTAR Electric 6.0 7.5 PSNH 1.7 1.7 E. 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, long-term debt and RRBs. 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. Uncategorized - Investments that are measured at net asset value are not categorized within the fair value hierarchy. 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 11, "Fair Value of Financial Instruments," to the financial statements. F. Investments in Unconsolidated Affiliates Revolution Wind and South Fork Wind: On February 8, 2019, Eversource and Ørsted entered into a 50-50 partnership for key offshore wind assets in the Northeast. Eversource's initial payment and contribution under the terms of the partnership agreements totaled approximately $225 million for a 50 percent interest in North East Offshore LLC, which holds the Revolution Wind and South Fork Wind power projects, as well as a 257 -square-mile tract off the coasts of Massachusetts and Rhode Island. This equity investment is included in long-term assets on the balance sheet and earnings impacts are included in Other Income, Net on the statement of income. G. Other Income, Net The components of Other Income, Net on the statements of income were as follows: For the Three Months Ended March 31, 2019 March 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Pension, SERP and PBOP Non-Service Income Components $ 7.4 $ (0.6 ) $ 7.0 $ 0.5 $ 15.2 $ 3.0 $ 8.4 $ 2.3 AFUDC Equity 10.9 2.6 4.0 0.2 9.7 2.8 3.4 — Equity in Earnings 5.0 — 0.2 — 4.6 — — — Investment Income/(Loss) 1.2 1.7 (0.3 ) 0.4 0.7 (0.1 ) 0.6 — Interest Income (1) 6.5 0.4 0.2 5.9 3.5 0.9 0.2 2.4 Other — (0.2 ) — — 0.1 — — — Total Other Income, Net $ 31.0 $ 3.9 $ 11.1 $ 7.0 $ 33.8 $ 6.6 $ 12.6 $ 4.7 (1) See Note 2, "Regulatory Accounting" for interest income recognized in 2019 for the equity return component of carrying charges on storm costs at PSNH. H. Other Taxes Eversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers. These gross receipts taxes are recorded 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 (Millions of Dollars) March 31, 2019 March 31, 2018 Eversource $ 45.0 $ 43.4 CL&P 36.2 35.6 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. Separate from the amounts above are $10.7 million and $12.7 million of amounts recorded as Taxes Other than Income Taxes for the three months ended March 31, 2019 and 2018, respectively, related to the future remittance to the State of Connecticut of energy efficiency funds collected from customers in Operating Revenues. These amounts are recorded separately, with collections in Operating Revenues and with payments in Taxes Other than Income Taxes on the Eversource and CL&P statements of income. I. Supplemental Cash Flow Information Non-cash investing activities include plant additions included in Accounts Payable as follows: (Millions of Dollars) As of March 31, 2019 As of March 31, 2018 Eversource $ 336.3 $ 274.4 CL&P 121.9 117.7 NSTAR Electric 83.2 59.5 PSNH 30.4 36.0 The following table reconciles cash as reported on the balance sheets to the cash and restricted cash balance as reported on the statements of cash flows: As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Cash as reported on the Balance Sheets $ 35.1 $ 7.5 $ 1.8 $ 4.0 $ 108.1 $ 87.7 $ 1.6 $ 1.4 Restricted cash included in: Prepayments and Other Current Assets 45.9 3.6 13.0 21.1 72.1 3.5 13.0 47.5 Marketable Securities 24.2 0.3 0.1 0.5 25.9 0.4 0.1 0.6 Other Long-Term Assets 3.2 — — 3.2 3.2 — — 3.2 Cash and Restricted Cash reported on the Statements of Cash Flows $ 108.4 $ 11.4 $ 14.9 $ 28.8 $ 209.3 $ 91.6 $ 14.7 $ 52.7 Restricted cash included in Prepayments and Other Current Assets and Other Long-Term Assets primarily represents cash collections related to the PSNH RRB customer charges that are held in trust, and required ISO-NE cash deposits. R estricted cash included in Marketable Securities represents money market funds held in trusts to fund certain non-qualified executive benefits and restricted trusts to fund CYAPC and YAEC's spent nuclear fuel storage facilities obligations.

REGULATORY ACCOUNTING

REGULATORY ACCOUNTING	3 Months Ended
	Mar. 31, 2019
Regulated Operations [Abstract]
REGULATORY ACCOUNTING	REGULATORY ACCOUNTING Eversource's utility 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 its 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 March 31, 2019 As of December 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Benefit Costs $ 1,878.7 $ 416.0 $ 534.9 $ 165.8 $ 1,914.8 $ 424.7 $ 544.4 $ 169.6 Income Taxes, Net 730.9 454.3 106.1 8.0 728.6 454.4 105.9 8.3 Securitized Stranded Costs 597.7 — — 597.7 608.4 — — 608.4 Storm Restoration Costs, Net 579.0 307.4 204.4 67.2 576.0 302.6 212.9 60.5 Regulatory Tracker Mechanisms 317.7 54.4 160.2 78.0 316.0 33.2 169.1 67.3 Derivative Liabilities 353.5 353.1 — — 356.5 356.5 — — Goodwill-related 344.2 — 295.5 — 348.4 — 299.1 — Asset Retirement Obligations 92.8 32.8 44.9 3.4 89.2 32.3 42.2 3.3 Other Regulatory Assets 202.2 26.4 62.6 11.9 208.0 27.0 64.6 12.1 Total Regulatory Assets 5,096.7 1,644.4 1,408.6 932.0 5,145.9 1,630.7 1,438.2 929.5 Less: Current Portion 507.3 147.7 234.7 76.6 514.8 125.2 241.7 67.2 Total Long-Term Regulatory Assets $ 4,589.4 $ 1,496.7 $ 1,173.9 $ 855.4 $ 4,631.1 $ 1,505.5 $ 1,196.5 $ 862.3 Storm Filings: On November 16, 2018, CL&P filed for recovery of $153 million of storm costs incurred from October 2017 through May 2018, with recovery over six years to begin May 1, 2019. Through the course of the proceeding, CL&P updated its request to $145.5 million to reflect final invoicing and capitalization amounts. On April 17, 2019, PURA authorized recovery of $141.0 million as part of storm cost recovery and the remainder to be recorded to capital or other balance sheet accounts. On March 26, 2019, the NHPUC approved the recovery of $38.1 million , plus carrying charges, of storm costs incurred from December 2013 through April 2016 and the transfer of funding from PSNH’s major storm reserve to recover those costs. The costs of these storms (excluding the equity return component of the carrying charges) were deferred as regulatory assets, and the funding reserve collected from customers was accrued as a regulatory liability. As a result of the duration of time between incurring storm costs in December 2013 through April 2016 and final approval from the NHPUC in 2019, PSNH recognized $5.2 million (pre-tax) for the equity return component of the carrying charges within Other Income, Net on the statement of income in the first quarter of 2019, which has been collected from customers. Also included in the March 26, 2019 NHPUC approval is a prospective requirement for PSNH to annually net its storm funding reserve collected from customers against deferred storm costs. Regulatory Costs in Long-Term Assets: Eversource's regulated companies had $129.5 million (including $41.9 million for CL&P, $52.8 million for NSTAR Electric and $13.9 million for PSNH) and $122.9 million (including $42.1 million for CL&P, $49.3 million for NSTAR Electric and $12.2 million for PSNH) of additional regulatory costs as of March 31, 2019 and December 31, 2018 , respectively, that were included in 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 March 31, 2019 As of December 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH EDIT due to Tax Cuts and Jobs Act $ 2,871.4 $ 1,030.7 $ 1,096.7 $ 394.6 $ 2,883.0 $ 1,031.0 $ 1,103.7 $ 396.4 Cost of Removal 535.0 46.2 313.4 22.1 521.0 39.9 307.1 22.1 Benefit Costs 87.2 — 73.6 — 91.2 — 76.9 — Regulatory Tracker Mechanisms 332.5 79.5 166.7 39.9 309.0 89.5 163.7 48.3 AFUDC - Transmission 71.4 47.1 24.3 — 70.7 47.4 23.3 — Revenue Subject to Refund due to Tax Cuts and Jobs Act 27.0 — — 15.8 24.6 — — 12.6 Other Regulatory Liabilities 88.3 29.3 33.9 3.2 80.2 24.0 29.2 4.2 Total Regulatory Liabilities 4,012.8 1,232.8 1,708.6 475.6 3,979.7 1,231.8 1,703.9 483.6 Less: Current Portion 385.4 106.5 194.0 45.7 370.2 109.6 190.6 55.5 Total Long-Term Regulatory Liabilities $ 3,627.4 $ 1,126.3 $ 1,514.6 $ 429.9 $ 3,609.5 $ 1,122.2 $ 1,513.3 $ 428.1

PROPERTY, PLANT AND EQUIPMENT A

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION	PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION The following tables summarize property, plant and equipment by asset category: Eversource As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) Distribution - Electric $ 15,245.9 $ 15,071.1 Distribution - Natural Gas 3,635.6 3,546.2 Transmission - Electric 10,251.1 10,153.9 Distribution - Water 1,649.5 1,639.8 Solar 169.9 164.1 Utility 30,952.0 30,575.1 Other (1) 798.3 778.6 Property, Plant and Equipment, Gross 31,750.3 31,353.7 Less: Accumulated Depreciation Utility (7,229.5 ) (7,126.2 ) Other (348.7 ) (336.7 ) Total Accumulated Depreciation (7,578.2 ) (7,462.9 ) Property, Plant and Equipment, Net 24,172.1 23,890.8 Construction Work in Progress 1,860.7 1,719.6 Total Property, Plant and Equipment, Net $ 26,032.8 $ 25,610.4 As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Distribution - Electric $ 6,255.8 $ 6,828.5 $ 2,201.8 $ 6,176.4 $ 6,756.4 $ 2,178.6 Transmission - Electric 4,746.4 4,085.6 1,370.2 4,700.5 4,065.9 1,338.7 Solar — 169.9 — — 164.1 — Property, Plant and Equipment, Gross 11,002.2 11,084.0 3,572.0 10,876.9 10,986.4 3,517.3 Less: Accumulated Depreciation (2,328.0 ) (2,749.9 ) (789.3 ) (2,302.6 ) (2,702.0 ) (772.9 ) Property, Plant and Equipment, Net 8,674.2 8,334.1 2,782.7 8,574.3 8,284.4 2,744.4 Construction Work in Progress 391.7 581.5 137.9 335.4 510.3 135.7 Total Property, Plant and Equipment, Net $ 9,065.9 $ 8,915.6 $ 2,920.6 $ 8,909.7 $ 8,794.7 $ 2,880.1 (1) These assets are primarily comprised of building improvements, computer software, hardware and equipment at Eversource Service.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS	DERIVATIVE INSTRUMENTS The electric and natural gas 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. These regulated companies manage the risks associated with the price volatility of energy and energy-related products through the use of derivative and non-derivative 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 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 electric and natural gas 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 March 31, 2019 As of December 31, 2018 (Millions of Dollars) Fair Value Hierarchy 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: CL&P Level 3 $ 10.4 $ (1.9 ) $ 8.5 $ 9.6 $ (3.4 ) $ 6.2 Other Level 2 — — — 1.5 (0.9 ) 0.6 Long-Term Derivative Assets: CL&P Level 3 73.1 (2.2 ) 70.9 74.2 (2.3 ) 71.9 Current Derivative Liabilities: CL&P Level 3 (59.7 ) — (59.7 ) (55.1 ) — (55.1 ) Other Level 2 (0.4 ) 0.2 (0.2 ) — — — Long-Term Derivative Liabilities: CL&P Level 3 (372.8 ) — (372.8 ) (379.5 ) — (379.5 ) Other Level 2 (0.2 ) — (0.2 ) — — — (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 1E, "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. As of March 31, 2019 and December 31, 2018 , Eversource had New York Mercantile Exchange ("NYMEX") financial contracts for natural gas futures in order to reduce variability associated with the price of 6.2 million and 12.5 million MMBtu of natural gas, respectively. For the three months ended March 31, 2019 and 2018 , there were losses of $5.2 million and $36.1 million , respectively, deferred as regulatory costs, which reflect the change in fair value associated with Eversource's derivative contracts. 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 related 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 term 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 CL&P'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 March 31, 2019 As of December 31, 2018 CL&P Range Period Covered Range Period Covered Capacity Prices $ 4.30 — 7.34 per kW-Month 2023 - 2026 $ 4.30 — 7.44 per kW-Month 2022 - 2026 Forward Reserve 0.75 — 1.78 per kW-Month 2019 - 2024 0.75 — 1.78 per kW-Month 2019 - 2024 Exit price premiums of 3.7 percent through 15.1 percent are also applied to these contracts and reflect the uncertainty and illiquidity premiums that would be required based on the most recent market activity available for similar type contracts. Significant increases or decreases in future capacity or forward reserve 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. CL&P For the Three Months Ended March 31, (Millions of Dollars) 2019 2018 Derivatives, Net: Fair Value as of Beginning of Period $ (356.5 ) $ (362.3 ) Net Realized/Unrealized Losses Included in Regulatory Assets (5.3 ) (36.9 ) Settlements 8.7 12.7 Fair Value as of End of Period $ (353.1 ) $ (386.5 )

MARKETABLE SECURITIES

MARKETABLE SECURITIES	3 Months Ended
	Mar. 31, 2019
Investments, Debt and Equity Securities [Abstract]
MARKETABLE SECURITIES	MARKETABLE SECURITIES Eversource holds marketable securities that are primarily used to fund certain non-qualified executive benefits. The trusts that hold marketable securities 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 spent nuclear fuel removal obligations of their nuclear fuel storage facilities. Equity Securities: Unrealized gains and losses on equity securities held in Eversource's non-qualified executive benefit trust are recorded in Other Income, Net on the statements of income. The fair value of these equity securities as of March 31, 2019 and December 31, 2018 was $49.6 million and $44.0 million , respectively. For the three months ended March 31, 2019 and 2018, there were unrealized gains of $1.0 million and unrealized losses of $0.7 million , respectively, recorded in Other Income, Net related to these equity securities. Eversource's equity securities also include CYAPC's and YAEC's marketable securities held in spent nuclear fuel trusts, which had fair values of $166.6 million and $200.0 million as of March 31, 2019 and December 31, 2018, respectively. Unrealized gains and losses for these spent nuclear fuel trusts are subject to regulatory accounting treatment and 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. Available-for-Sale Debt Securities: The following is a summary of the available-for-sale debt securities, which are recorded at fair value and are included in current and long-term Marketable Securities on the balance sheets. As of March 31, 2019 As of December 31, 2018 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 $ 212.3 $ 0.9 $ (0.9 ) $ 212.3 $ 190.0 $ 0.4 $ (4.0 ) $ 186.4 Eversource's debt securities include CYAPC's and YAEC's marketable securities held in spent nuclear fuel trusts in the amounts of $170.7 million and $143.9 million as of March 31, 2019 and December 31, 2018 , respectively. Unrealized gains and losses on available-for-sale debt securities held in Eversource's non-qualified benefit trust are recorded in Accumulated Other Comprehensive Income. There have been no significant unrealized losses, other-than-temporary impairments, or credit losses for the three months ended March 31, 2019 and 2018 . 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. As of March 31, 2019 , 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) $ 29.7 $ 29.6 One to five years 48.5 48.5 Six to ten years 39.0 39.4 Greater than ten years 95.1 94.8 Total Debt Securities $ 212.3 $ 212.3 (1) Amounts in the Less than one year category include securities in the CYAPC and YAEC spent nuclear fuel trusts, which are restricted and are classified in long-term Marketable Securities on the balance sheets. Realized Gains and Losses: Realized gains and losses 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 non-qualified benefit trust, and the average cost basis method for the CYAPC and YAEC spent nuclear fuel trusts to compute the realized gains and losses on the sale of marketable securities. 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 March 31, 2019 As of December 31, 2018 Level 1: Mutual Funds and Equities $ 216.2 $ 244.0 Money Market Funds 24.2 25.9 Total Level 1 $ 240.4 $ 269.9 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 104.3 $ 79.6 Corporate Debt Securities 44.7 39.5 Asset-Backed Debt Securities 13.9 14.0 Municipal Bonds 16.0 19.2 Other Fixed Income Securities 9.2 8.2 Total Level 2 $ 188.1 $ 160.5 Total Marketable Securities $ 428.5 $ 430.4 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 instruments 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.

SHORT-TERM AND LONG-TERM DEBT

SHORT-TERM AND LONG-TERM DEBT	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
SHORT-TERM AND LONG-TERM DEBT	SHORT-TERM AND LONG-TERM DEBT Short-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. Eversource parent, CL&P, PSNH, NSTAR Gas and Yankee Gas are also parties to a five -year $1.45 billion revolving credit facility, which terminates on December 8, 2023. The revolving credit facility serves to backstop Eversource parent's $1.45 billion commercial paper program. NSTAR Electric has a $650 million commercial paper program allowing NSTAR Electric to issue commercial paper as a form of short-term debt. NSTAR Electric is also a party to a five -year $650 million revolving credit facility, which terminates on December 8, 2023 . The revolving credit facility serves to backstop NSTAR Electric's $650 million commercial paper program. The amount of borrowings outstanding and available under the commercial paper programs were as follows: Borrowings Outstanding as of Available Borrowing Capacity as of Weighted-Average Interest Rate as of March 31, 2019 December 31, 2018 March 31, 2019 December 31, 2018 March 31, 2019 December 31, 2018 (Millions of Dollars) Eversource Parent Commercial Paper Program $ 1,371.0 $ 631.5 $ 79.0 $ 818.5 2.69 % 2.77 % NSTAR Electric Commercial Paper Program 368.4 278.5 281.6 371.5 2.49 % 2.50 % There were no borrowings outstanding on either the Eversource parent or NSTAR Electric revolving credit facilities as of March 31, 2019 or December 31, 2018 . Eversource's water distribution segment has a $100 million revolving credit facility, which expires on August 19, 2019 , and there were no borrowings outstanding as of March 31, 2019 or December 31, 2018 . Amounts outstanding under the commercial paper programs and revolving credit facility are included in Notes Payable and are classified in current liabilities on the Eversource and NSTAR Electric balance sheets as all borrowings are outstanding for no more than 364 days at one time. As a result of the CL&P long-term debt issuance on April 1, 2019 , the net proceeds of which were used to repay CL&P's short-term borrowings, $261.6 million of commercial paper borrowings under the Eversource parent commercial paper program were reclassified to Long-Term Debt as of March 31, 2019 . We expect the future operating cash flows of Eversource, CL&P, NSTAR Electric and PSNH, along with our existing borrowing availability and access to both debt and equity markets, will be sufficient to meet any working capital and future operating requirements, and capital investment forecasted opportunities. Intercompany Borrowings: Eversource parent uses its available capital resources to provide loans to its subsidiaries to assist them in meeting their short-term borrowing needs. In addition, growth in Eversource's key business initiatives requires cash infusion to those subsidiaries. Eversource parent records intercompany interest income from its loans to subsidiaries, which is eliminated in consolidation. Intercompany loans from Eversource parent to its subsidiaries are eliminated in consolidation on Eversource's balance sheets. As of March 31, 2019 , there were intercompany loans from Eversource parent to CL&P of $261.6 million , to PSNH of $61.0 million , and to Harbor Electric Energy Company, a wholly-owned subsidiary of NSTAR Electric ("HEEC"), of $22.3 million . As of December 31, 2018 , there were intercompany loans from Eversource parent to PSNH of $57.0 million . Intercompany loans from Eversource parent are included in Notes Payable to Eversource Parent and are classified in current liabilities on the respective subsidiary's balance sheets. As a result of the CL&P long-term debt issuance on April 1, 2019 , $261.6 million of CL&P's intercompany borrowings were reclassified to Long-Term Debt as of March 31, 2019 . The proceeds from the CL&P April 1, 2019 debt issuance were used to repay CL&P’s short-term borrowings that were outstanding as of March 31, 2019, and to fund capital expenditures and working capital. Long-Term Debt: The following table summarizes long-term debt issuances and repayments: (Millions of Dollars) Issue Date Issuance/(Repayment) Maturity Date Use of Proceeds for Issuance/ CL&P: 4.00% 2018 Series A First Mortgage Bonds (1) April 2019 $ 300.0 April 2048 Repaid short-term borrowings that were used to repay long-term debt that matured on February 1, 2019 and fund capital expenditures and working capital 5.50% 2009 Series A First Mortgage Bonds February 2009 (250.0 ) February 2019 Repaid at maturity on February 1, 2019 (1) These bonds are part of the same series issued by CL&P in March 2018. The aggregate outstanding principal amount of these bonds is now $800 million .

RATE REDUCTION BONDS AND VARIAB

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES	3 Months Ended
	Mar. 31, 2019
Rate Reduction Bonds and Variable Interest Entity [Abstract]
RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES	RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES Rate Reduction Bonds: On May 8, 2018, PSNH Funding, a wholly-owned subsidiary of PSNH, issued $635.7 million of securitized RRBs in multiple tranches with a weighted average interest rate of 3.66 percent , and final maturity dates ranging from 2026 to 2035. The RRBs are expected to be repaid by February 1, 2033. RRB payments consist of principal and interest and will be paid semi-annually, beginning on February 1, 2019. The RRBs were issued pursuant to a finance order issued by the NHPUC on January 30, 2018 to recover remaining costs resulting from the divestiture of PSNH’s generation assets. PSNH Funding is considered a VIE primarily because the equity capitalization is insufficient to support its operations. PSNH has the power to direct the significant activities of the VIE and is most closely associated with the VIE as compared to other interest holders. Therefore, PSNH is considered the primary beneficiary and consolidates PSNH Funding in its consolidated financial statements. The following tables summarize the impact of PSNH Funding on PSNH's balance sheets and income statements: (Millions of Dollars) Balance Sheet: As of March 31, 2019 As of December 31, 2018 Restricted Cash - Current Portion (included in Prepayments and Other Current Assets) $ 21.1 $ 47.5 Restricted Cash - Long-Term Portion (included in Other Long-Term Assets) 3.2 3.2 Securitized Stranded Cost (included in Regulatory Assets) 597.7 608.4 Other Regulatory Liabilities (included in Regulatory Liabilities) 10.0 5.8 Accrued Interest (included in Other Current Liabilities) 3.5 14.4 Rate Reduction Bonds - Current Portion 43.2 52.3 Rate Reduction Bonds - Long-Term Portion 561.7 583.3 (Millions of Dollars) For the Three Months Ended Income Statement: March 31, 2019 March 31, 2018 Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net) $ 10.6 $ — Interest Expense on RRB Principal (included in Interest Expense) 5.4 —

PENSION BENEFITS AND POSTRETIRE

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION	3 Months Ended
	Mar. 31, 2019
Postemployment Benefits [Abstract]
PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION	PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION Eversource provides defined benefit retirement plans ("Pension Plans") that cover eligible employees. In addition to the Pension Plans, Eversource maintains non-qualified defined benefit retirement plans ("SERP Plans"), which provide benefits in excess of Internal Revenue Code limitations to eligible participants consisting of current and retired employees. Eversource also provides defined benefit postretirement plans ("PBOP Plans") that provide life insurance and a health reimbursement arrangement created for the purpose of reimbursing retirees and dependents for health insurance premiums and certain medical expenses to eligible employees that meet certain age and service eligibility requirements. The components of net periodic benefit expense/(income) for the Pension, SERP and PBOP Plans, prior to amounts capitalized as Property, Plant and Equipment or deferred as regulatory assets for future recovery, are shown below. The service cost component of net periodic benefit expense and the intercompany allocations, less the capitalized portions, are included in Operations and Maintenance expense on the statements of income. The remaining components of net periodic benefit expense for pension, SERP and PBOP are included in Other Income, Net on the statements of income. Pension, SERP and PBOP expense reflected in the statements of cash flows for CL&P, NSTAR Electric and PSNH does not include the intercompany allocations or the corresponding capitalized and deferred portion, as these amounts are cash settled on a short-term basis. Pension and SERP For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 19.3 $ 4.8 $ 3.9 $ 2.6 $ 22.7 $ 5.7 $ 4.7 $ 2.9 Interest Cost 54.2 11.5 11.9 6.2 48.4 10.6 10.8 5.3 Expected Return on Pension Plan Assets (92.3 ) (18.8 ) (24.4 ) (10.3 ) (98.0 ) (20.8 ) (25.2 ) (10.9 ) Actuarial Loss 35.8 8.1 9.4 3.5 36.0 7.4 10.5 3.3 Prior Service Cost 1.1 — 0.1 — 2.2 0.4 0.2 0.1 Total Net Periodic Benefit Expense $ 18.1 $ 5.6 $ 0.9 $ 2.0 $ 11.3 $ 3.3 $ 1.0 $ 0.7 Intercompany Allocations N/A $ 7.8 $ 3.0 $ 2.4 N/A $ 1.4 $ 1.5 $ 0.5 PBOP For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 2.1 $ 0.4 $ 0.4 $ 0.2 $ 2.7 $ 0.5 $ 0.5 $ 0.3 Interest Cost 8.1 1.5 2.3 0.9 7.6 1.4 2.2 0.8 Expected Return on Plan Assets (16.6 ) (2.3 ) (7.5 ) (1.3 ) (18.1 ) (2.6 ) (8.1 ) (1.5 ) Actuarial Loss 2.5 0.4 0.9 0.2 2.6 0.3 0.7 0.2 Prior Service Cost/(Credit) (5.8 ) 0.3 (4.2 ) 0.1 (5.9 ) 0.3 (4.3 ) 0.1 Total Net Periodic Benefit Expense/(Income) $ (9.7 ) $ 0.3 $ (8.1 ) $ 0.1 $ (11.1 ) $ (0.1 ) $ (9.0 ) $ (0.1 ) Intercompany Allocations N/A $ (0.1 ) $ (0.2 ) $ (0.1 ) N/A $ (0.3 ) $ (0.3 ) $ (0.1 )

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES A. Environmental Matters Eversource, CL&P, NSTAR Electric and PSNH 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 and PSNH 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 March 31, 2019 As of December 31, 2018 Number of Sites Reserve (in millions) Number of Sites Reserve (in millions) Eversource 59 $ 64.8 60 $ 64.7 CL&P 15 5.6 15 5.4 NSTAR Electric 15 10.5 16 10.9 PSNH 9 5.3 9 5.4 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 $50.6 million and $50.1 million as of March 31, 2019 and December 31, 2018 , 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 and PSNH'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 required environmental remediation. As this information becomes available, management will continue to assess the potential exposure and adjust the reserves accordingly. B. Long-Term Contractual Arrangements On December 28, 2018 , under Public Act 17-3, "An Act Concerning Zero Carbon Procurement," DEEP selected the Millstone Nuclear Power Station generation facility, along with smaller generation facilities, in DEEP’s zero-carbon request for proposal. CL&P and UI were directed by DEEP to enter into ten -year contracts to purchase a combined total of approximately 9 million MWh annually from the Millstone generation facility. On March 15, 2019 , CL&P and UI each signed a ten - year contract with the owner of Millstone Nuclear Power Station in order to purchase a combined amount of approximately 50 percent of the facility's output (approximately 40 percent by CL&P). The Millstone Nuclear Power Station has a 2,112 MW nameplate capacity. The parties filed the contract with PURA on March 29, 2019 for review and approval. A decision from PURA is expected in the third quarter of 2019. The significant output of the generation facility, the contract period, and the pricing will result in a significant multi-billion dollar commitment. We plan to sell the energy purchased under this contract into the market and use the proceeds from these energy sales to offset the contract costs. As the net costs under this contract will be recovered from customers in future rates, the contract will not have an impact on the net income of CL&P. C. Guarantees and Indemnifications In the normal course of business, Eversource parent provides credit assurances on behalf of its subsidiaries, including CL&P, NSTAR Electric and PSNH, in the form of guarantees. 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 a facility with a financial institution pursuant to which NPT may request letters of credit in an aggregate amount of up to approximately $14 million . Management does not anticipate a material impact to net income or cash flows 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 March 31, 2019 : Company Description Maximum Exposure (in millions) Expiration Dates On behalf of subsidiaries: Eversource Investment LLC Revolution Wind and South Fork Wind (1) $ 113.9 - Various Surety Bonds (2) 32.0 2019 - 2021 Rocky River Realty Company and Eversource Service Lease Payments for Real Estate 7.3 2024 Bay State Wind LLC Real Estate Purchase 2.5 2019 (1) Eversource parent issued a declining balance guaranty on behalf of its subsidiary, Eversource Investment LLC. Eversource parent will guarantee, as a primary obligor, the financial obligations, primarily all post-closing payment obligations of Eversource Investment LLC, under the Sale and Purchase Agreement and an Irrevocable Equity Commitment Letter with Ørsted. Eversource parent's obligations under the guaranty expire upon the full, final and indefeasible payment of the guaranteed obligations. (2) 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. Eversource parent issued a declining balance guaranty on behalf of its subsidiary, Eversource Gas Transmission LLC, to guarantee the payment of the subsidiary's authorized capital contributions for its investment in the Access Northeast project. As of March 31, 2019, the amount of the Access Northeast project capital contribution guaranty was $184.8 million . On April 1, 2019, pursuant to a provision in the partnership agreement jointly entered into by Eversource, Enbridge, Inc. and National Grid plc, through Algonquin Gas Transmission, LLC, the Access Northeast project was terminated. The rights under the guaranty were released, which terminated the obligation of Eversource parent. D. Spent Nuclear Fuel Obligations - Yankee Companies CL&P, NSTAR Electric and PSNH have plant closure and fuel storage cost obligations to the Yankee Companies, which have each completed the physical decommissioning of their respective nuclear facilities and are now engaged in the long-term storage of their spent fuel. The Yankee Companies fund these costs through litigation proceeds received from the DOE and, to the extent necessary, through wholesale, FERC-approved rates charged under power purchase agreements with several New England utilities, including CL&P, NSTAR Electric and PSNH. CL&P, NSTAR Electric and PSNH, in turn recover these costs from their customers through state regulatory commission-approved retail rates. The Yankee Companies collect amounts that management believes are adequate to recover the remaining plant closure and fuel storage cost estimates for the respective plants. Management believes CL&P and NSTAR Electric will recover their shares of these obligations from their customers. PSNH has recovered its total share of these costs from its customers. Spent Nuclear Fuel Litigation: The Yankee Companies have filed 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, II and III of litigation resulting from the DOE's failure to meet its contractual obligations. These Phases covered damages incurred in the years 1998 through 2012, and the awarded damages have been received by the Yankee Companies with certain amounts of the damages refunded to their customers. DOE Phase IV Damages - On May 22, 2017, each of the Yankee Companies filed subsequent lawsuits against the DOE in the Court of Federal Claims. The Yankee Companies sought monetary damages totaling $104.4 million for CYAPC, YAEC and MYAPC, resulting from the DOE's failure to begin accepting spent nuclear fuel for disposal covering the years from 2013 to 2016 (“DOE Phase IV”). On February 21, 2019, the Yankee Companies received a partial summary judgment and partial final judgment in their favor for the undisputed amount of monetary damages of $103.2 million . The court awarded CYAPC, YAEC and MYAPC damages of $40.7 million , $28.1 million and $34.4 million , respectively. The DOE did not appeal the court's judgment and the decision became final on April 23, 2019. The DOE Phase IV trial for the $1.2 million of remaining damages is expected to begin in June 2019. E. FERC ROE Complaints Four separate complaints have been filed at the 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 each of the first three complaints, filed on October 1, 2011, December 27, 2012, and July 31, 2014, respectively, the Complainants challenged the NETOs' base ROE of 11.14 percent that had been utilized since 2005 and sought an order to reduce it prospectively from the date of the final FERC order and for the separate 15 -month complaint periods. In the fourth complaint, filed April 29, 2016, the Complainants challenged the NETOs' base ROE billed of 10.57 percent and the maximum ROE for transmission incentive ("incentive cap") of 11.74 percent , asserting that these ROEs were unjust and unreasonable. The ROE originally billed during the period October 1, 2011 (beginning of the first complaint period) through October 15, 2014 consisted of a base ROE of 11.14 percent and incentives up to 13.1 percent . On October 16, 2014, the FERC set the base ROE at 10.57 percent and the incentive cap at 11.74 percent for the first complaint period. This was also effective for all prospective billings to customers beginning October 16, 2014. This FERC order was vacated on April 14, 2017 by the U.S. Court of Appeals for the D.C. Circuit (the "Court"). All amounts associated with the first complaint period have been refunded, which totaled $38.9 million (pre-tax and excluding interest) at Eversource and reflected both the base ROE and incentive cap prescribed by the FERC order. The refund consisted of $22.4 million for CL&P, $13.7 million for NSTAR Electric and $2.8 million for PSNH. Eversource has recorded a reserve of $39.1 million (pre-tax and excluding interest) for the second complaint period as of March 31, 2019. This reserve represents the difference between the billed rates during the second complaint period and a 10.57 percent base ROE and 11.74 percent incentive cap. The reserve consisted of $21.4 million for CL&P, $14.6 million for NSTAR Electric and $3.1 million for PSNH as of March 31, 2019 . On October 16, 2018, FERC issued an order on all four complaints describing how it intends to address the issues that were remanded by the Court. FERC proposed a new framework to determine (1) whether an existing ROE is unjust and unreasonable and, if so, (2) how to calculate a replacement ROE. The parties to these proceedings were directed to submit briefs on this new proposed framework and how they would apply the proposed framework in each of the four complaint proceedings. Initial briefs were filed by the NETOs, Complainants and FERC Trial Staff on January 11, 2019 and reply briefs were filed on March 8, 2019. The NETOs' brief was supportive of the overall ROE methodology determined in the October 16, 2018 order provided the FERC does not change the proposed methodology or alter its implementation in a manner that has a material impact on the results. The FERC order included illustrative calculations for the first complaint using FERC's proposed frameworks with financial data from that complaint. Those preliminary calculations indicated that for the first complaint period, for the NETOs that FERC concludes are of average financial risk, (1) a preliminary range of presumptively just and reasonable base ROEs is 9.60 percent to 10.99 percent ; (2) the pre-existing base ROE of 11.14 percent is therefore unjust and unreasonable; (3) the preliminary just and reasonable base ROE is 10.41 percent ; and (4) the preliminary incentive cap on total ROE is 13.08 percent . If the results of these illustrative calculations were included in a final FERC order for each of the complaint periods, then a 10.41 percent base ROE and a 13.08 percent incentive cap would not have a significant impact on our financial statements for all of the complaint periods. Although the order provided illustrative calculations, FERC stated that these calculations are merely preliminary. The FERC’s preliminary calculations are not binding and do not represent what we believe to be the most likely outcome of a final FERC order, as changes to the methodology by FERC are possible as a result of the parties’ arguments and calculations in the briefing process. Until FERC issues a final decision on each of these four complaints, there is significant uncertainty, and at this time, the Company cannot reasonably estimate a range of gain or loss for any of the four complaint proceedings. The October 16, 2018 FERC order or the 2019 briefs did not provide a reasonable basis for a change to the reserve or recognized ROEs for any of the complaint periods. Eversource, CL&P, NSTAR Electric and PSNH currently record revenues at the 10.57 percent base ROE and incentive cap at 11.74 percent established in the October 16, 2014 FERC order. The average impact of a 10 basis point change to the base ROE for each of the 15 -month complaint periods would affect Eversource's after-tax earnings by approximately $3 million . F. Eversource and NSTAR Electric Boston Harbor Civil Action On July 15, 2016, the United States Attorney on behalf of 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, HEEC, and the Massachusetts Water Resources Authority (together with NSTAR Electric and HEEC, the "Defendants"). The action alleged that the Defendants failed to comply with certain permitting requirements related to the placement of the HEEC-owned electric distribution cable beneath Boston Harbor. The action sought an order to compel HEEC to comply with cable depth requirements in the United States Army Corps of Engineers' permit or alternatively to remove the electric distribution cable and cease unauthorized work in U.S. waterways. The action also sought civil penalties and other costs. The parties reached a settlement pursuant to which HEEC agreed to install a new 115 kV distribution cable across Boston Harbor to Deer Island, utilizing a different route, and remove portions of the existing cable. Upon the installation and completion of the new cable and the removal of the portions of the existing cable, all issues surrounding the current permit from the United States Army Corps of Engineers are expected to be resolved, and such litigation is expected to be dismissed with prejudice. NSTAR Electric agreed to provide a rate base credit of $17.5 million to the Massachusetts Water Resources Authority for the new cable. This negotiated credit resulted in the initial $17.5 million of construction costs on the new cable being expensed as incurred, all of which was fully expensed in 2018. Construction of the new cable is underway and is expected to be completed in 2019.

LEASES

LEASES	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
LEASES	LEASES Eversource, including CL&P, NSTAR Electric and PSNH, has entered into lease agreements as a lessee for the use of land, office space, service centers, vehicles, information technology, and equipment. These lease agreements are classified as either finance or operating leases and the liability and right-of-use asset are recognized on the balance sheet at lease commencement. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term. Eversource determines whether or not a contract contains a lease based on whether or not it provides Eversource with the use of a specifically identified asset for a period of time, as well as both the right to direct the use of that asset and receive the significant economic benefits of the asset. Eversource has elected the practical expedient to not separate non-lease components from lease components and instead to account for both as a single lease component, with the exception of the information technology asset class where the lease and non-lease components are separated. The provisions of Eversource, CL&P, NSTAR Electric and PSNH lease agreements contain renewal options. The renewal options range from one year to twenty years . The renewal period is included in the measurement of the lease liability if it is reasonably certain that Eversource will exercise these renewal options. For leases entered into or modified after the January 1, 2019 implementation date, the discount rate utilized for classification and measurement purposes as of the inception date of the lease is based on each company's collateralized incremental interest rate to borrow over a comparable term for an individual lease, as the rate implicit in the lease is not determinable. CL&P and PSNH entered into certain contracts for the purchase of energy that qualify as leases. These contracts do not have minimum lease payments and therefore are not recognized as a lease liability on the balance sheet and are not reflected in the future minimum lease payments table below. Expense related to these contracts are included as variable lease cost in the table below. The expense and long-term obligation for these contracts are included in the annually reported contractual obligations table in Note 12B, "Commitments and Contingencies - Long-Term Contractual Arrangements," of the Eversource 2018 Form 10-K. The components of lease cost, prior to amounts capitalized, are as follows: For the Three Months Ended March 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Financing Lease Cost: Amortization of Right-of-use-Assets $ 0.4 $ 0.2 $ — $ — Interest on Lease Liabilities 0.3 0.1 0.3 — Total Finance Lease Cost 0.7 0.3 0.3 — Operating Lease Cost 3.0 0.1 0.5 — Variable Lease Cost 15.5 3.5 — 12.0 Total Lease Cost $ 19.2 $ 3.9 $ 0.8 $ 12.0 Operating lease cost, less the capitalized portion, is included in Operations and Maintenance (or Purchased Power, Fuel and Transmission expense for transmission segment leases) on the statements of income. Amortization of finance lease assets is included in Depreciation on the statements of income. Interest expense on finance leases is included in Interest Expense, Net on the statements of income. Supplemental balance sheet information related to leases is as follows: As of March 31, 2019 (Millions of Dollars) Balance Sheet Classification Eversource CL&P NSTAR Electric PSNH Operating Leases: Operating Lease Right-of-use-Assets, Net Other Long-Term Assets $ 56.7 $ 0.5 $ 25.1 $ 0.5 Operating Lease Liabilities Operating Lease Liabilities - Current Portion Other Current Liabilities $ 9.2 $ 0.3 $ 0.8 $ 0.1 Operating Lease Liabilities - Long-Term Other Long-Term Liabilities 47.5 0.2 24.3 0.4 Total Operating Lease Liabilities $ 56.7 $ 0.5 $ 25.1 $ 0.5 Finance Leases: Finance Lease Right-of-use-Assets, Net Property, Plant and Equipment, Net $ 8.8 $ 2.9 $ 3.5 $ 0.9 Finance Lease Liabilities Finance Lease Liabilities - Current Portion Other Current Liabilities $ 1.9 $ 1.5 $ — $ 0.1 Finance Lease Liabilities - Long-Term Other Long-Term Liabilities 9.1 2.7 4.5 0.8 Total Finance Lease Liabilities $ 11.0 $ 4.2 $ 4.5 $ 0.9 The finance lease payments that NSTAR Electric will make over the next twelve months are entirely interest-related, due to escalating payments. As such, none of the finance lease payments over the next twelve months will reduce the finance lease liability. Other information related to leases is as follows (in millions of dollars, unless otherwise noted): For the Three Months Ended March 31, 2019 Eversource CL&P NSTAR Electric PSNH Weighted-Average Remaining Lease Term (Years): Operating Leases 12 3 21 8 Financing Leases 11 3 23 10 Weighted-Average Discount Rate (Percentage): Operating Leases 3.8 % 3.2 % 4.1 % 3.6 % Financing Leases 4.5 % 10.5 % 2.9 % 3.5 % Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 2.9 $ 0.1 $ 0.3 $ — Operating Cash Flows from Finance Leases 0.3 0.2 0.1 — Financing Cash Flows from Finance Leases 0.4 0.3 — — Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 1.3 — — — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 1.3 — — — Future minimum lease payments, excluding variable costs, under long-term leases, as of March 31, 2019 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH April 1, 2019 through December 31, 2019 $ 8.3 $ 0.2 $ 1.4 $ 0.1 $ 2.5 $ 1.5 $ 0.4 $ 0.1 Year Ending December 31, 2020 9.6 0.2 1.6 0.1 3.4 2.0 0.5 0.1 2021 8.7 — 1.6 0.1 2.9 1.5 0.5 0.1 2022 7.3 — 1.6 0.1 1.5 — 0.6 0.1 2023 4.8 — 1.6 0.1 0.7 — 0.6 0.1 2024 2.8 — 1.7 0.1 0.7 — 0.6 0.1 Thereafter 29.7 0.1 29.4 0.1 13.2 — 12.8 0.4 Future lease payments 71.2 0.5 38.9 0.7 24.9 5.0 16.0 1.0 Less amount representing interest 14.5 — 13.8 0.2 13.9 0.8 11.5 0.1 Present value of future minimum lease payments $ 56.7 $ 0.5 $ 25.1 $ 0.5 $ 11.0 $ 4.2 $ 4.5 $ 0.9 At December 31, 2018, future minimum rental payments, excluding executory costs, such as property taxes, state use taxes, insurance, and maintenance were as follows: Operating Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2019 $ 11.5 $ 1.5 $ 7.2 $ 0.5 2020 9.8 1.4 6.0 0.4 2021 8.7 1.2 5.3 0.4 2022 7.2 1.1 4.4 0.4 2023 4.7 0.5 3.1 0.2 Thereafter 32.7 0.2 29.5 0.3 Future minimum lease payments $ 74.6 $ 5.9 $ 55.5 $ 2.2 Capital Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2019 $ 3.4 $ 2.0 $ 0.5 $ 0.1 2020 3.4 2.0 0.5 0.1 2021 2.9 1.5 0.5 0.1 2022 1.5 — 0.6 0.1 2023 0.7 — 0.6 0.1 Thereafter 13.9 — 13.4 0.5 Future minimum lease payments 25.8 5.5 16.1 1.0 Less amount representing interest 13.8 1.0 12.4 0.1 Present value of future minimum lease payments $ 12.0 $ 4.5 $ 3.7 $ 0.9
LEASES	LEASES Eversource, including CL&P, NSTAR Electric and PSNH, has entered into lease agreements as a lessee for the use of land, office space, service centers, vehicles, information technology, and equipment. These lease agreements are classified as either finance or operating leases and the liability and right-of-use asset are recognized on the balance sheet at lease commencement. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term. Eversource determines whether or not a contract contains a lease based on whether or not it provides Eversource with the use of a specifically identified asset for a period of time, as well as both the right to direct the use of that asset and receive the significant economic benefits of the asset. Eversource has elected the practical expedient to not separate non-lease components from lease components and instead to account for both as a single lease component, with the exception of the information technology asset class where the lease and non-lease components are separated. The provisions of Eversource, CL&P, NSTAR Electric and PSNH lease agreements contain renewal options. The renewal options range from one year to twenty years . The renewal period is included in the measurement of the lease liability if it is reasonably certain that Eversource will exercise these renewal options. For leases entered into or modified after the January 1, 2019 implementation date, the discount rate utilized for classification and measurement purposes as of the inception date of the lease is based on each company's collateralized incremental interest rate to borrow over a comparable term for an individual lease, as the rate implicit in the lease is not determinable. CL&P and PSNH entered into certain contracts for the purchase of energy that qualify as leases. These contracts do not have minimum lease payments and therefore are not recognized as a lease liability on the balance sheet and are not reflected in the future minimum lease payments table below. Expense related to these contracts are included as variable lease cost in the table below. The expense and long-term obligation for these contracts are included in the annually reported contractual obligations table in Note 12B, "Commitments and Contingencies - Long-Term Contractual Arrangements," of the Eversource 2018 Form 10-K. The components of lease cost, prior to amounts capitalized, are as follows: For the Three Months Ended March 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Financing Lease Cost: Amortization of Right-of-use-Assets $ 0.4 $ 0.2 $ — $ — Interest on Lease Liabilities 0.3 0.1 0.3 — Total Finance Lease Cost 0.7 0.3 0.3 — Operating Lease Cost 3.0 0.1 0.5 — Variable Lease Cost 15.5 3.5 — 12.0 Total Lease Cost $ 19.2 $ 3.9 $ 0.8 $ 12.0 Operating lease cost, less the capitalized portion, is included in Operations and Maintenance (or Purchased Power, Fuel and Transmission expense for transmission segment leases) on the statements of income. Amortization of finance lease assets is included in Depreciation on the statements of income. Interest expense on finance leases is included in Interest Expense, Net on the statements of income. Supplemental balance sheet information related to leases is as follows: As of March 31, 2019 (Millions of Dollars) Balance Sheet Classification Eversource CL&P NSTAR Electric PSNH Operating Leases: Operating Lease Right-of-use-Assets, Net Other Long-Term Assets $ 56.7 $ 0.5 $ 25.1 $ 0.5 Operating Lease Liabilities Operating Lease Liabilities - Current Portion Other Current Liabilities $ 9.2 $ 0.3 $ 0.8 $ 0.1 Operating Lease Liabilities - Long-Term Other Long-Term Liabilities 47.5 0.2 24.3 0.4 Total Operating Lease Liabilities $ 56.7 $ 0.5 $ 25.1 $ 0.5 Finance Leases: Finance Lease Right-of-use-Assets, Net Property, Plant and Equipment, Net $ 8.8 $ 2.9 $ 3.5 $ 0.9 Finance Lease Liabilities Finance Lease Liabilities - Current Portion Other Current Liabilities $ 1.9 $ 1.5 $ — $ 0.1 Finance Lease Liabilities - Long-Term Other Long-Term Liabilities 9.1 2.7 4.5 0.8 Total Finance Lease Liabilities $ 11.0 $ 4.2 $ 4.5 $ 0.9 The finance lease payments that NSTAR Electric will make over the next twelve months are entirely interest-related, due to escalating payments. As such, none of the finance lease payments over the next twelve months will reduce the finance lease liability. Other information related to leases is as follows (in millions of dollars, unless otherwise noted): For the Three Months Ended March 31, 2019 Eversource CL&P NSTAR Electric PSNH Weighted-Average Remaining Lease Term (Years): Operating Leases 12 3 21 8 Financing Leases 11 3 23 10 Weighted-Average Discount Rate (Percentage): Operating Leases 3.8 % 3.2 % 4.1 % 3.6 % Financing Leases 4.5 % 10.5 % 2.9 % 3.5 % Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 2.9 $ 0.1 $ 0.3 $ — Operating Cash Flows from Finance Leases 0.3 0.2 0.1 — Financing Cash Flows from Finance Leases 0.4 0.3 — — Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 1.3 — — — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 1.3 — — — Future minimum lease payments, excluding variable costs, under long-term leases, as of March 31, 2019 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH April 1, 2019 through December 31, 2019 $ 8.3 $ 0.2 $ 1.4 $ 0.1 $ 2.5 $ 1.5 $ 0.4 $ 0.1 Year Ending December 31, 2020 9.6 0.2 1.6 0.1 3.4 2.0 0.5 0.1 2021 8.7 — 1.6 0.1 2.9 1.5 0.5 0.1 2022 7.3 — 1.6 0.1 1.5 — 0.6 0.1 2023 4.8 — 1.6 0.1 0.7 — 0.6 0.1 2024 2.8 — 1.7 0.1 0.7 — 0.6 0.1 Thereafter 29.7 0.1 29.4 0.1 13.2 — 12.8 0.4 Future lease payments 71.2 0.5 38.9 0.7 24.9 5.0 16.0 1.0 Less amount representing interest 14.5 — 13.8 0.2 13.9 0.8 11.5 0.1 Present value of future minimum lease payments $ 56.7 $ 0.5 $ 25.1 $ 0.5 $ 11.0 $ 4.2 $ 4.5 $ 0.9 At December 31, 2018, future minimum rental payments, excluding executory costs, such as property taxes, state use taxes, insurance, and maintenance were as follows: Operating Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2019 $ 11.5 $ 1.5 $ 7.2 $ 0.5 2020 9.8 1.4 6.0 0.4 2021 8.7 1.2 5.3 0.4 2022 7.2 1.1 4.4 0.4 2023 4.7 0.5 3.1 0.2 Thereafter 32.7 0.2 29.5 0.3 Future minimum lease payments $ 74.6 $ 5.9 $ 55.5 $ 2.2 Capital Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2019 $ 3.4 $ 2.0 $ 0.5 $ 0.1 2020 3.4 2.0 0.5 0.1 2021 2.9 1.5 0.5 0.1 2022 1.5 — 0.6 0.1 2023 0.7 — 0.6 0.1 Thereafter 13.9 — 13.4 0.5 Future minimum lease payments 25.8 5.5 16.1 1.0 Less amount representing interest 13.8 1.0 12.4 0.1 Present value of future minimum lease payments $ 12.0 $ 4.5 $ 3.7 $ 0.9

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2019
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, Long-Term Debt and Rate Reduction Bonds: 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 and RRB 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 table below are classified as Level 2 within the fair value hierarchy. Carrying amounts and estimated fair values are as follows: Eversource CL&P NSTAR Electric PSNH (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value As of March 31, 2019: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 157.1 $ 116.2 $ 114.2 $ 43.0 $ 42.9 $ — $ — Long-Term Debt 13,089.8 13,519.6 3,265.8 3,538.0 2,945.2 3,107.3 805.3 831.1 Rate Reduction Bonds 604.9 623.3 — — — — 604.9 623.3 As of December 31, 2018: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 156.8 $ 116.2 $ 113.8 $ 43.0 $ 43.0 $ — $ — Long-Term Debt 13,086.1 13,154.9 3,254.0 3,429.2 2,944.8 3,024.1 805.2 819.5 Rate Reduction Bonds 635.7 645.8 — — — — 635.7 645.8 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 1E, "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)	3 Months Ended
	Mar. 31, 2019
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, are as follows: For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 Eversource (Millions of Dollars) Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Qualified Cash Flow Hedging Instruments Unrealized Losses on Marketable Securities Defined Benefit Plans Total Balance as of January 1st $ (4.4 ) $ (0.5 ) $ (55.1 ) $ (60.0 ) $ (6.2 ) $ — $ (60.2 ) $ (66.4 ) OCI Before Reclassifications — 0.7 — 0.7 — (0.4 ) — (0.4 ) Amounts Reclassified from AOCI 0.3 — 1.2 1.5 0.7 — 3.0 3.7 Net OCI 0.3 0.7 1.2 2.2 0.7 (0.4 ) 3.0 3.3 Balance as of March 31st $ (4.1 ) $ 0.2 $ (53.9 ) $ (57.8 ) $ (5.5 ) $ (0.4 ) $ (57.2 ) $ (63.1 ) 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, NSTAR Electric and PSNH 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 that arose during the year and were recognized in AOCI. The unamortized actuarial gains and losses and prior service costs on the defined benefit plans are amortized from AOCI into Other Income, Net over the average future employee service period, and are reflected in amounts reclassified from AOCI.

COMMON SHARES

COMMON SHARES	3 Months Ended
	Mar. 31, 2019
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 and PSNH that were authorized and issued, as well as the respective per share par values: Shares Authorized as of March 31, 2019 and December 31, 2018 Issued as of Par Value March 31, 2019 December 31, 2018 Eversource $ 5 380,000,000 333,878,402 333,878,402 CL&P $ 10 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 200 200 PSNH $ 1 100,000,000 301 301 As of March 31, 2019 and December 31, 2018 , there were 16,530,932 and 16,992,594 Eversource common shares held as treasury shares, respectively. As of March 31, 2019 and December 31, 2018 , Eversource common shares outstanding were 317,347,470 and 316,885,808 , respectively. Beginning in 2019, Eversource began issuing treasury shares to satisfy awards under the Company's incentive plan, shares issued under the dividend reinvestment plan, and matching contributions under the Eversource 401k Plan. COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for each of the three months ended March 31, 2019 and 2018 . 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 March 31, 2019 and December 31, 2018 . On the Eversource balance sheets, Common Shareholders' Equity was fully attributable to Eversource 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	3 Months Ended
	Mar. 31, 2019
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 and PSNH that were authorized and issued, as well as the respective per share par values: Shares Authorized as of March 31, 2019 and December 31, 2018 Issued as of Par Value March 31, 2019 December 31, 2018 Eversource $ 5 380,000,000 333,878,402 333,878,402 CL&P $ 10 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 200 200 PSNH $ 1 100,000,000 301 301 As of March 31, 2019 and December 31, 2018 , there were 16,530,932 and 16,992,594 Eversource common shares held as treasury shares, respectively. As of March 31, 2019 and December 31, 2018 , Eversource common shares outstanding were 317,347,470 and 316,885,808 , respectively. Beginning in 2019, Eversource began issuing treasury shares to satisfy awards under the Company's incentive plan, shares issued under the dividend reinvestment plan, and matching contributions under the Eversource 401k Plan. COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for each of the three months ended March 31, 2019 and 2018 . 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 March 31, 2019 and December 31, 2018 . On the Eversource balance sheets, Common Shareholders' Equity was fully attributable to Eversource parent and Noncontrolling Interest – Preferred Stock of Subsidiaries was fully attributable to the noncontrolling interest.

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2019
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 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. The following table sets forth the components of basic and diluted EPS: Eversource (Millions of Dollars, except share information) For the Three Months Ended March 31, 2019 March 31, 2018 Net Income Attributable to Common Shareholders $ 308.7 $ 269.5 Weighted Average Common Shares Outstanding: Basic 317,624,593 317,397,052 Dilutive Effect 691,489 595,947 Diluted 318,316,082 317,992,999 Basic and Diluted EPS $ 0.97 $ 0.85

REVENUES

REVENUES	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
REVENUES	REVENUES The following tables present operating revenues disaggregated by revenue source: For the Three Months Ended March 31, 2019 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 1,033.3 $ 258.9 $ — $ 27.0 $ — $ — $ 1,319.2 Commercial 652.6 143.8 — 14.3 — (1.1 ) 809.6 Industrial 82.1 30.9 — 1.1 — (2.7 ) 111.4 Total Retail Tariff Sales Revenues 1,768.0 433.6 — 42.4 — (3.8 ) 2,240.2 Wholesale Transmission Revenues — — 324.9 — 13.5 (270.8 ) 67.6 Wholesale Market Sales Revenues 51.5 21.7 — 1.0 — — 74.2 Other Revenues from Contracts with Customers 12.6 0.9 3.2 1.7 244.6 (245.4 ) 17.6 Reserve for Revenues Subject to Refund (3.1 ) 1.6 — (0.8 ) — — (2.3 ) Total Revenues from Contracts with Customers 1,829.0 457.8 328.1 44.3 258.1 (520.0 ) 2,397.3 Alternative Revenue Programs 2.1 10.4 12.4 0.9 — (11.1 ) 14.7 Other Revenues (1) 2.8 0.7 — 0.3 — — 3.8 Total Operating Revenues $ 1,833.9 $ 468.9 $ 340.5 $ 45.5 $ 258.1 $ (531.1 ) $ 2,415.8 For the Three Months Ended March 31, 2018 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 994.4 $ 248.9 $ — $ 26.4 $ — $ — $ 1,269.7 Commercial 611.4 134.7 — 13.8 — — 759.9 Industrial 81.5 29.5 — 1.0 — (2.5 ) 109.5 Total Retail Tariff Sales Revenues 1,687.3 413.1 — 41.2 — (2.5 ) 2,139.1 Wholesale Transmission Revenues — — 313.6 — 10.1 (258.7 ) 65.0 Wholesale Market Sales Revenues 58.5 17.8 — 0.8 — — 77.1 Other Revenues from Contracts with Customers 16.0 (0.6 ) 3.1 4.0 220.8 (221.4 ) 21.9 Reserve for Revenues Subject to Refund (19.3 ) (4.5 ) — (2.2 ) — — (26.0 ) Total Revenues from Contracts with Customers 1,742.5 425.8 316.7 43.8 230.9 (482.6 ) 2,277.1 Alternative Revenue Programs 8.7 (1.7 ) (11.7 ) 0.7 — 10.6 6.6 Other Revenues 3.4 0.8 — 0.1 — — 4.3 Total Operating Revenues $ 1,754.6 $ 424.9 $ 305.0 $ 44.6 $ 230.9 $ (472.0 ) $ 2,288.0 For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Revenues from Contracts with Customers Retail Tariff Sales Residential $ 510.5 $ 371.0 $ 151.8 $ 483.4 $ 364.2 $ 146.8 Commercial 236.7 336.5 79.8 222.5 314.4 74.9 Industrial 34.6 28.8 18.7 35.8 28.1 17.6 Total Retail Tariff Sales Revenues 781.8 736.3 250.3 741.7 706.7 239.3 Wholesale Transmission Revenues 154.8 122.6 47.5 150.8 118.6 44.2 Wholesale Market Sales Revenues 13.7 24.4 13.4 10.3 24.9 24.1 Other Revenues from Contracts with Customers 8.9 4.0 3.6 7.5 8.3 3.5 Reserve for Revenues Subject to Refund — — (3.1 ) (12.5 ) (3.7 ) (3.1 ) Total Revenues from Contracts with Customers 959.2 887.3 311.7 897.8 854.8 308.0 Alternative Revenue Programs 5.7 7.3 1.5 (5.1 ) 6.7 (4.6 ) Other Revenues (1) 1.0 1.5 0.3 1.3 1.7 0.4 Eliminations (116.7 ) (98.5 ) (37.1 ) (109.0 ) (93.1 ) (36.4 ) Total Operating Revenues $ 849.2 $ 797.6 $ 276.4 $ 785.0 $ 770.1 $ 267.4 (1) Other Revenues include certain fees charged to customers, which are not considered revenue from contracts with customers. Other revenues also includes lease revenues under lessor accounting guidance of $1.0 million at Eversource, $0.2 million at CL&P, and $0.6 million at NSTAR Electric for the three months ended March 31, 2019.

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION Eversource is organized into the Electric Distribution, Electric Transmission, Natural Gas Distribution and Water 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, natural gas and water primarily are derived from residential, commercial and industrial customers and are not dependent on any single customer. The Electric Distribution reportable segment includes the results of PSNH's generation facilities prior to sales in January and August 2018, and NSTAR Electric's solar power facilities. 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. 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) Eversource Water Ventures, Inc., parent company of Aquarion, and 5) the results of other unregulated subsidiaries, which are not part of its core business. In addition, Other in the tables below includes Eversource parent's equity ownership interests that are not consolidated, which include a natural gas pipeline project owned by Enbridge, Inc., the offshore wind business, a renewable energy investment fund, and two companies that transmit hydroelectricity imported from the Hydro-Quebec system in Canada. In the ordinary course of business, Yankee Gas and NSTAR Gas purchase natural gas transmission services from the Enbridge, Inc. natural gas pipeline project described above. These affiliate transaction costs total approximately $62.5 million annually and are classified as Purchased Power, Fuel and Transmission on the Eversource statements of income. Each of Eversource's subsidiaries, including CL&P, NSTAR Electric and PSNH, has one reportable segment. 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 and PBOP expense. Eversource's segment information is as follows: For the Three Months Ended March 31, 2019 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 1,833.9 $ 468.9 $ 340.5 $ 45.5 $ 258.1 $ (531.1 ) $ 2,415.8 Depreciation and Amortization (179.2 ) (20.4 ) (61.5 ) (11.8 ) (13.6 ) 0.6 (285.9 ) Other Operating Expenses (1,475.6 ) (341.3 ) (98.8 ) (25.0 ) (225.5 ) 531.0 (1,635.2 ) Operating Income $ 179.1 $ 107.2 $ 180.2 $ 8.7 $ 19.0 $ 0.5 $ 494.7 Interest Expense $ (49.2 ) $ (11.7 ) $ (30.6 ) $ (8.6 ) $ (44.2 ) $ 12.6 $ (131.7 ) Other Income, Net 18.2 0.2 8.1 0.4 431.7 (427.6 ) 31.0 Net Income Attributable to Common Shareholders 120.1 76.5 118.2 0.9 407.5 (414.5 ) 308.7 Cash Flows Used for Investments in Plant 279.3 87.4 231.4 20.7 55.9 — 674.7 For the Three Months Ended March 31, 2018 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 1,754.6 $ 424.9 $ 305.0 $ 44.6 $ 230.9 $ (472.0 ) $ 2,288.0 Depreciation and Amortization (144.4 ) (26.4 ) (56.6 ) (10.7 ) (12.0 ) 0.6 (249.5 ) Other Operating Expenses (1,443.5 ) (312.6 ) (83.2 ) (23.9 ) (204.7 ) 471.9 (1,596.0 ) Operating Income $ 166.7 $ 85.9 $ 165.2 $ 10.0 $ 14.2 $ 0.5 $ 442.5 Interest Expense $ (47.4 ) $ (11.1 ) $ (29.7 ) $ (8.4 ) $ (31.9 ) $ 7.4 $ (121.1 ) Other Income/(Loss), Net 19.6 2.0 8.0 (0.6 ) 360.1 (355.3 ) 33.8 Net Income Attributable to Common Shareholders 104.2 57.8 107.4 1.5 346.0 (347.4 ) 269.5 Cash Flows Used for Investments in Plant 236.0 70.4 239.2 19.0 42.7 — 607.3 The following table summarizes Eversource's segmented total assets: Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Water Distribution Other Eliminations Total As of March 31, 2019 $ 21,507.0 $ 4,019.1 $ 10,533.4 $ 2,268.3 $ 18,939.8 $ (18,326.6 ) $ 38,941.0 As of December 31, 2018 21,389.1 3,904.9 10,285.0 2,253.0 17,874.2 (17,464.9 ) 38,241.3

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2019
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 and PSNH (electric utilities), Yankee Gas and NSTAR Gas (natural gas utilities) and Aquarion (water utilities). Eversource provides energy delivery and/or water service to approximately four million electric, natural gas and water customers through eight 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 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 2018 Form 10-K, which was filed with the SEC on February 26, 2019. 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 and PSNH's financial position as of March 31, 2019 and December 31, 2018 , and the results of operations, comprehensive income, common shareholders' equity, and cash flows for the three months ended March 31, 2019 and 2018 . The results of operations, comprehensive income, and cash flows for the three months ended March 31, 2019 and 2018 are not necessarily indicative of the results expected for a full year. Eversource consolidates CYAPC and YAEC because CL&P's, NSTAR Electric's and PSNH's combined ownership and voting interests in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements. Eversource's utility subsidiaries' electric, natural gas and water distribution 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.
Accounting Standards	Accounting Standards Accounting Standards Issued but Not Yet Effective: In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses. Under the new guidance, immediate recognition of all credit losses expected over the life of a financial instrument is required. The new standard also revises the other-than-temporary impairment model for available-for-sale debt securities . The standard is effective January 1, 2020, and requires a modified retrospective transition approach through a cumulative-effect adjustment to retained earnings. The Company is assessing the impacts of this standard on the accounting for credit losses on its financial instruments, including accounts receivable. Accounting Standards Recently Adopted: On January 1, 2019, the Company adopted ASU 2016-02, Leases (Topic 842), which amended existing lease accounting guidance. The Company applied the Topic 842 lease criteria to new leases and lease renewals entered into effective on or after January 1, 2019. The ASU required balance sheet recognition of leases deemed to be operating leases as well as additional disclosure requirements. The recognition, measurement and presentation of expenses and cash flows were not significantly changed. The Company also adopted the modified retrospective transition method allowed in ASU 2018-11, Leases (Topic 842) - Targeted Improvements , which allowed the Company to adopt the new leases standard as of January 1, 2019, with prior periods presented in the financial statements continuing to follow existing lease accounting guidance under Topic 840 (Leases) in the accounting literature. Implementation of ASU 2018-11 had no effect on retained earnings, and the requirements of the new lease standard (Topic 842) are reflected in the 2019 financial statements and footnotes. The Company elected the practical expedient package whereby it did not need to reassess whether or not an existing contract is or contains a lease or whether a lease is an operating or capital lease, and it did not need to reassess initial direct costs for leases. Election of this practical expedient allowed us to carry forward our historical lease classifications. The Company elected the practical expedient to not reevaluate land easements existing at adoption if they were not previously accounted for as leases. The Company also elected to use the discount rate as of the January 1, 2019 implementation date to discount its operating lease liabilities. The Company did not elect the hindsight practical expedient to determine the lease term for existing leases. The Company determined the impact the ASUs had on its financial statements by reviewing its lease population and identifying lease data needed for the disclosure requirements. The Company implemented a new lease accounting system in 2019 to ensure ongoing compliance with the ASU’s requirements. Adoption of the new standard resulted in the recording of operating lease liabilities and right-of-use assets on the balance sheet upon transition at January 1, 2019 of $58.0 million at Eversource, $25.3 million at NSTAR Electric, $0.6 million at CL&P, and $0.6 million at PSNH. Implementation of the new guidance did not have an impact on each company’s results of operations or cash flows.
Provision for Uncollectible Accounts	Provision for Uncollectible Accounts Eversource, including CL&P, NSTAR Electric and PSNH, 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 NSTAR Electric and NSTAR Gas to recover in rates, amounts associated with certain uncollectible hardship accounts receivable. These uncollectible hardship 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, long-term debt and RRBs. 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. Uncategorized - Investments that are measured at net asset value are not categorized within the fair value hierarchy.
Other Taxes	Other Taxes Eversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers. 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. Separate from the amounts above are $10.7 million and $12.7 million of amounts recorded as Taxes Other than Income Taxes for the three months ended March 31, 2019 and 2018, respectively, related to the future remittance to the State of Connecticut of energy efficiency funds collected from customers in Operating Revenues. These amounts are recorded separately, with collections in Operating Revenues and with payments in Taxes Other than Income Taxes on the Eversource and CL&P statements of income.
Restricted Cash	Restricted cash included in Prepayments and Other Current Assets and Other Long-Term Assets primarily represents cash collections related to the PSNH RRB customer charges that are held in trust, and required ISO-NE cash deposits. R estricted cash included in Marketable Securities represents money market funds held in trusts to fund certain non-qualified executive benefits and restricted trusts to fund CYAPC and YAEC's spent nuclear fuel storage facilities obligations.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Provision for Uncollectible Accounts	Total Provision for Uncollectible Accounts Provision for Uncollectible Hardship Accounts (Millions of Dollars) As of March 31, 2019 As of December 31, 2018 As of March 31, 2019 As of December 31, 2018 Eversource $ 223.3 $ 212.7 $ 134.6 $ 131.5 CL&P 93.0 88.0 75.2 71.9 NSTAR Electric 74.8 74.5 40.9 42.5 PSNH 11.0 11.1 — — Uncollectible expense associated with customers' accounts receivable included in Operations and Maintenance expense on the statements of income is as follows: For the Three Months Ended (Millions of Dollars) March 31, 2019 March 31, 2018 Eversource $ 18.6 $ 19.6 CL&P 4.1 3.9 NSTAR Electric 6.0 7.5 PSNH 1.7 1.7
Components of Other Income, Net	The components of Other Income, Net on the statements of income were as follows: For the Three Months Ended March 31, 2019 March 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Pension, SERP and PBOP Non-Service Income Components $ 7.4 $ (0.6 ) $ 7.0 $ 0.5 $ 15.2 $ 3.0 $ 8.4 $ 2.3 AFUDC Equity 10.9 2.6 4.0 0.2 9.7 2.8 3.4 — Equity in Earnings 5.0 — 0.2 — 4.6 — — — Investment Income/(Loss) 1.2 1.7 (0.3 ) 0.4 0.7 (0.1 ) 0.6 — Interest Income (1) 6.5 0.4 0.2 5.9 3.5 0.9 0.2 2.4 Other — (0.2 ) — — 0.1 — — — Total Other Income, Net $ 31.0 $ 3.9 $ 11.1 $ 7.0 $ 33.8 $ 6.6 $ 12.6 $ 4.7 (1) See Note 2, "Regulatory Accounting" for interest income recognized in 2019 for the equity return component of carrying charges on storm costs at PSNH.
Other Taxes	These gross receipts taxes are recorded 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 (Millions of Dollars) March 31, 2019 March 31, 2018 Eversource $ 45.0 $ 43.4 CL&P 36.2 35.6
Non-cash Investing Activities	Non-cash investing activities include plant additions included in Accounts Payable as follows: (Millions of Dollars) As of March 31, 2019 As of March 31, 2018 Eversource $ 336.3 $ 274.4 CL&P 121.9 117.7 NSTAR Electric 83.2 59.5 PSNH 30.4 36.0
Reconciliation of Cash Balances to Cash and Restricted Cash	The following table reconciles cash as reported on the balance sheets to the cash and restricted cash balance as reported on the statements of cash flows: As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Cash as reported on the Balance Sheets $ 35.1 $ 7.5 $ 1.8 $ 4.0 $ 108.1 $ 87.7 $ 1.6 $ 1.4 Restricted cash included in: Prepayments and Other Current Assets 45.9 3.6 13.0 21.1 72.1 3.5 13.0 47.5 Marketable Securities 24.2 0.3 0.1 0.5 25.9 0.4 0.1 0.6 Other Long-Term Assets 3.2 — — 3.2 3.2 — — 3.2 Cash and Restricted Cash reported on the Statements of Cash Flows $ 108.4 $ 11.4 $ 14.9 $ 28.8 $ 209.3 $ 91.6 $ 14.7 $ 52.7

REGULATORY ACCOUNTING (Tables)

REGULATORY ACCOUNTING (Tables)	3 Months Ended
	Mar. 31, 2019
Regulated Operations [Abstract]
Components of Regulatory Assets	The components of regulatory assets were as follows: As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Benefit Costs $ 1,878.7 $ 416.0 $ 534.9 $ 165.8 $ 1,914.8 $ 424.7 $ 544.4 $ 169.6 Income Taxes, Net 730.9 454.3 106.1 8.0 728.6 454.4 105.9 8.3 Securitized Stranded Costs 597.7 — — 597.7 608.4 — — 608.4 Storm Restoration Costs, Net 579.0 307.4 204.4 67.2 576.0 302.6 212.9 60.5 Regulatory Tracker Mechanisms 317.7 54.4 160.2 78.0 316.0 33.2 169.1 67.3 Derivative Liabilities 353.5 353.1 — — 356.5 356.5 — — Goodwill-related 344.2 — 295.5 — 348.4 — 299.1 — Asset Retirement Obligations 92.8 32.8 44.9 3.4 89.2 32.3 42.2 3.3 Other Regulatory Assets 202.2 26.4 62.6 11.9 208.0 27.0 64.6 12.1 Total Regulatory Assets 5,096.7 1,644.4 1,408.6 932.0 5,145.9 1,630.7 1,438.2 929.5 Less: Current Portion 507.3 147.7 234.7 76.6 514.8 125.2 241.7 67.2 Total Long-Term Regulatory Assets $ 4,589.4 $ 1,496.7 $ 1,173.9 $ 855.4 $ 4,631.1 $ 1,505.5 $ 1,196.5 $ 862.3
Components of Regulatory Liabilities	The components of regulatory liabilities were as follows: As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH EDIT due to Tax Cuts and Jobs Act $ 2,871.4 $ 1,030.7 $ 1,096.7 $ 394.6 $ 2,883.0 $ 1,031.0 $ 1,103.7 $ 396.4 Cost of Removal 535.0 46.2 313.4 22.1 521.0 39.9 307.1 22.1 Benefit Costs 87.2 — 73.6 — 91.2 — 76.9 — Regulatory Tracker Mechanisms 332.5 79.5 166.7 39.9 309.0 89.5 163.7 48.3 AFUDC - Transmission 71.4 47.1 24.3 — 70.7 47.4 23.3 — Revenue Subject to Refund due to Tax Cuts and Jobs Act 27.0 — — 15.8 24.6 — — 12.6 Other Regulatory Liabilities 88.3 29.3 33.9 3.2 80.2 24.0 29.2 4.2 Total Regulatory Liabilities 4,012.8 1,232.8 1,708.6 475.6 3,979.7 1,231.8 1,703.9 483.6 Less: Current Portion 385.4 106.5 194.0 45.7 370.2 109.6 190.6 55.5 Total Long-Term Regulatory Liabilities $ 3,627.4 $ 1,126.3 $ 1,514.6 $ 429.9 $ 3,609.5 $ 1,122.2 $ 1,513.3 $ 428.1

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Tables)	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Public Utility Property, Plant, and Equipment	The following tables summarize property, plant and equipment by asset category: Eversource As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) Distribution - Electric $ 15,245.9 $ 15,071.1 Distribution - Natural Gas 3,635.6 3,546.2 Transmission - Electric 10,251.1 10,153.9 Distribution - Water 1,649.5 1,639.8 Solar 169.9 164.1 Utility 30,952.0 30,575.1 Other (1) 798.3 778.6 Property, Plant and Equipment, Gross 31,750.3 31,353.7 Less: Accumulated Depreciation Utility (7,229.5 ) (7,126.2 ) Other (348.7 ) (336.7 ) Total Accumulated Depreciation (7,578.2 ) (7,462.9 ) Property, Plant and Equipment, Net 24,172.1 23,890.8 Construction Work in Progress 1,860.7 1,719.6 Total Property, Plant and Equipment, Net $ 26,032.8 $ 25,610.4 As of March 31, 2019 As of December 31, 2018 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Distribution - Electric $ 6,255.8 $ 6,828.5 $ 2,201.8 $ 6,176.4 $ 6,756.4 $ 2,178.6 Transmission - Electric 4,746.4 4,085.6 1,370.2 4,700.5 4,065.9 1,338.7 Solar — 169.9 — — 164.1 — Property, Plant and Equipment, Gross 11,002.2 11,084.0 3,572.0 10,876.9 10,986.4 3,517.3 Less: Accumulated Depreciation (2,328.0 ) (2,749.9 ) (789.3 ) (2,302.6 ) (2,702.0 ) (772.9 ) Property, Plant and Equipment, Net 8,674.2 8,334.1 2,782.7 8,574.3 8,284.4 2,744.4 Construction Work in Progress 391.7 581.5 137.9 335.4 510.3 135.7 Total Property, Plant and Equipment, Net $ 9,065.9 $ 8,915.6 $ 2,920.6 $ 8,909.7 $ 8,794.7 $ 2,880.1 (1) These assets are primarily comprised of building improvements, computer software, hardware and equipment at Eversource Service.

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Fair Values and Net Amounts of Contracts	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 March 31, 2019 As of December 31, 2018 (Millions of Dollars) Fair Value Hierarchy 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: CL&P Level 3 $ 10.4 $ (1.9 ) $ 8.5 $ 9.6 $ (3.4 ) $ 6.2 Other Level 2 — — — 1.5 (0.9 ) 0.6 Long-Term Derivative Assets: CL&P Level 3 73.1 (2.2 ) 70.9 74.2 (2.3 ) 71.9 Current Derivative Liabilities: CL&P Level 3 (59.7 ) — (59.7 ) (55.1 ) — (55.1 ) Other Level 2 (0.4 ) 0.2 (0.2 ) — — — Long-Term Derivative Liabilities: CL&P Level 3 (372.8 ) — (372.8 ) (379.5 ) — (379.5 ) Other Level 2 (0.2 ) — (0.2 ) — — — (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.
Summary of Level 3 Derivative Contracts and Significant Observable Inputs Used	The following is a summary of CL&P'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 March 31, 2019 As of December 31, 2018 CL&P Range Period Covered Range Period Covered Capacity Prices $ 4.30 — 7.34 per kW-Month 2023 - 2026 $ 4.30 — 7.44 per kW-Month 2022 - 2026 Forward Reserve 0.75 — 1.78 per kW-Month 2019 - 2024 0.75 — 1.78 per kW-Month 2019 - 2024
Changes in the Level 3 Category of Derivative Assets Measured at Fair Value on a Recurring Basis	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. CL&P For the Three Months Ended March 31, (Millions of Dollars) 2019 2018 Derivatives, Net: Fair Value as of Beginning of Period $ (356.5 ) $ (362.3 ) Net Realized/Unrealized Losses Included in Regulatory Assets (5.3 ) (36.9 ) Settlements 8.7 12.7 Fair Value as of End of Period $ (353.1 ) $ (386.5 )

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Debt Securities	The following is a summary of the available-for-sale debt securities, which are recorded at fair value and are included in current and long-term Marketable Securities on the balance sheets. As of March 31, 2019 As of December 31, 2018 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 $ 212.3 $ 0.9 $ (0.9 ) $ 212.3 $ 190.0 $ 0.4 $ (4.0 ) $ 186.4
Contractual Maturities of Available-for-Sale Debt Securities	As of March 31, 2019 , 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) $ 29.7 $ 29.6 One to five years 48.5 48.5 Six to ten years 39.0 39.4 Greater than ten years 95.1 94.8 Total Debt Securities $ 212.3 $ 212.3 (1) Amounts in the Less than one year category include securities in the CYAPC and YAEC spent nuclear fuel trusts, which are restricted and are classified in long-term Marketable Securities on the balance sheets.
Marketable Securities Recorded at Fair Value on a Recurring Basis by Level	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 March 31, 2019 As of December 31, 2018 Level 1: Mutual Funds and Equities $ 216.2 $ 244.0 Money Market Funds 24.2 25.9 Total Level 1 $ 240.4 $ 269.9 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 104.3 $ 79.6 Corporate Debt Securities 44.7 39.5 Asset-Backed Debt Securities 13.9 14.0 Municipal Bonds 16.0 19.2 Other Fixed Income Securities 9.2 8.2 Total Level 2 $ 188.1 $ 160.5 Total Marketable Securities $ 428.5 $ 430.4

SHORT-TERM AND LONG-TERM DEBT (

SHORT-TERM AND LONG-TERM DEBT (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Borrowings Outstanding and Available under the Commecrial Paper Programs	The amount of borrowings outstanding and available under the commercial paper programs were as follows: Borrowings Outstanding as of Available Borrowing Capacity as of Weighted-Average Interest Rate as of March 31, 2019 December 31, 2018 March 31, 2019 December 31, 2018 March 31, 2019 December 31, 2018 (Millions of Dollars) Eversource Parent Commercial Paper Program $ 1,371.0 $ 631.5 $ 79.0 $ 818.5 2.69 % 2.77 % NSTAR Electric Commercial Paper Program 368.4 278.5 281.6 371.5 2.49 % 2.50 %
Summary of Long-Term Debt Issuance and Repayments	The following table summarizes long-term debt issuances and repayments: (Millions of Dollars) Issue Date Issuance/(Repayment) Maturity Date Use of Proceeds for Issuance/ CL&P: 4.00% 2018 Series A First Mortgage Bonds (1) April 2019 $ 300.0 April 2048 Repaid short-term borrowings that were used to repay long-term debt that matured on February 1, 2019 and fund capital expenditures and working capital 5.50% 2009 Series A First Mortgage Bonds February 2009 (250.0 ) February 2019 Repaid at maturity on February 1, 2019 (1) These bonds are part of the same series issued by CL&P in March 2018. The aggregate outstanding principal amount of these bonds is now $800 million .

RATE REDUCTION BONDS AND VARI_2

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES (Tables)	3 Months Ended
	Mar. 31, 2019
Rate Reduction Bonds and Variable Interest Entity [Abstract]
Summary of the Impact of Funding on the Balance Sheets and Income Statements	The following tables summarize the impact of PSNH Funding on PSNH's balance sheets and income statements: (Millions of Dollars) Balance Sheet: As of March 31, 2019 As of December 31, 2018 Restricted Cash - Current Portion (included in Prepayments and Other Current Assets) $ 21.1 $ 47.5 Restricted Cash - Long-Term Portion (included in Other Long-Term Assets) 3.2 3.2 Securitized Stranded Cost (included in Regulatory Assets) 597.7 608.4 Other Regulatory Liabilities (included in Regulatory Liabilities) 10.0 5.8 Accrued Interest (included in Other Current Liabilities) 3.5 14.4 Rate Reduction Bonds - Current Portion 43.2 52.3 Rate Reduction Bonds - Long-Term Portion 561.7 583.3 (Millions of Dollars) For the Three Months Ended Income Statement: March 31, 2019 March 31, 2018 Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net) $ 10.6 $ — Interest Expense on RRB Principal (included in Interest Expense) 5.4 —

PENSION BENEFITS AND POSTRETI_2

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION (Tables)	3 Months Ended
	Mar. 31, 2019
Postemployment Benefits [Abstract]
Components of Net Periodic Benefit Expense/(Income)	The components of net periodic benefit expense/(income) for the Pension, SERP and PBOP Plans, prior to amounts capitalized as Property, Plant and Equipment or deferred as regulatory assets for future recovery, are shown below. The service cost component of net periodic benefit expense and the intercompany allocations, less the capitalized portions, are included in Operations and Maintenance expense on the statements of income. The remaining components of net periodic benefit expense for pension, SERP and PBOP are included in Other Income, Net on the statements of income. Pension, SERP and PBOP expense reflected in the statements of cash flows for CL&P, NSTAR Electric and PSNH does not include the intercompany allocations or the corresponding capitalized and deferred portion, as these amounts are cash settled on a short-term basis. Pension and SERP For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 19.3 $ 4.8 $ 3.9 $ 2.6 $ 22.7 $ 5.7 $ 4.7 $ 2.9 Interest Cost 54.2 11.5 11.9 6.2 48.4 10.6 10.8 5.3 Expected Return on Pension Plan Assets (92.3 ) (18.8 ) (24.4 ) (10.3 ) (98.0 ) (20.8 ) (25.2 ) (10.9 ) Actuarial Loss 35.8 8.1 9.4 3.5 36.0 7.4 10.5 3.3 Prior Service Cost 1.1 — 0.1 — 2.2 0.4 0.2 0.1 Total Net Periodic Benefit Expense $ 18.1 $ 5.6 $ 0.9 $ 2.0 $ 11.3 $ 3.3 $ 1.0 $ 0.7 Intercompany Allocations N/A $ 7.8 $ 3.0 $ 2.4 N/A $ 1.4 $ 1.5 $ 0.5 PBOP For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 2.1 $ 0.4 $ 0.4 $ 0.2 $ 2.7 $ 0.5 $ 0.5 $ 0.3 Interest Cost 8.1 1.5 2.3 0.9 7.6 1.4 2.2 0.8 Expected Return on Plan Assets (16.6 ) (2.3 ) (7.5 ) (1.3 ) (18.1 ) (2.6 ) (8.1 ) (1.5 ) Actuarial Loss 2.5 0.4 0.9 0.2 2.6 0.3 0.7 0.2 Prior Service Cost/(Credit) (5.8 ) 0.3 (4.2 ) 0.1 (5.9 ) 0.3 (4.3 ) 0.1 Total Net Periodic Benefit Expense/(Income) $ (9.7 ) $ 0.3 $ (8.1 ) $ 0.1 $ (11.1 ) $ (0.1 ) $ (9.0 ) $ (0.1 ) Intercompany Allocations N/A $ (0.1 ) $ (0.2 ) $ (0.1 ) N/A $ (0.3 ) $ (0.3 ) $ (0.1 )

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Environmental Sites and Related Reserves	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 March 31, 2019 As of December 31, 2018 Number of Sites Reserve (in millions) Number of Sites Reserve (in millions) Eversource 59 $ 64.8 60 $ 64.7 CL&P 15 5.6 15 5.4 NSTAR Electric 15 10.5 16 10.9 PSNH 9 5.3 9 5.4
Summary of Exposure to Guaruantees and Indemnifications	The following table summarizes Eversource parent's exposure to guarantees and indemnifications of its subsidiaries to external parties, as of March 31, 2019 : Company Description Maximum Exposure (in millions) Expiration Dates On behalf of subsidiaries: Eversource Investment LLC Revolution Wind and South Fork Wind (1) $ 113.9 - Various Surety Bonds (2) 32.0 2019 - 2021 Rocky River Realty Company and Eversource Service Lease Payments for Real Estate 7.3 2024 Bay State Wind LLC Real Estate Purchase 2.5 2019 (1) Eversource parent issued a declining balance guaranty on behalf of its subsidiary, Eversource Investment LLC. Eversource parent will guarantee, as a primary obligor, the financial obligations, primarily all post-closing payment obligations of Eversource Investment LLC, under the Sale and Purchase Agreement and an Irrevocable Equity Commitment Letter with Ørsted. Eversource parent's obligations under the guaranty expire upon the full, final and indefeasible payment of the guaranteed obligations. (2) 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.

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Components of Lease Cost	The components of lease cost, prior to amounts capitalized, are as follows: For the Three Months Ended March 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Financing Lease Cost: Amortization of Right-of-use-Assets $ 0.4 $ 0.2 $ — $ — Interest on Lease Liabilities 0.3 0.1 0.3 — Total Finance Lease Cost 0.7 0.3 0.3 — Operating Lease Cost 3.0 0.1 0.5 — Variable Lease Cost 15.5 3.5 — 12.0 Total Lease Cost $ 19.2 $ 3.9 $ 0.8 $ 12.0
Supplemental Balance Sheet Information Related to Leases	Supplemental balance sheet information related to leases is as follows: As of March 31, 2019 (Millions of Dollars) Balance Sheet Classification Eversource CL&P NSTAR Electric PSNH Operating Leases: Operating Lease Right-of-use-Assets, Net Other Long-Term Assets $ 56.7 $ 0.5 $ 25.1 $ 0.5 Operating Lease Liabilities Operating Lease Liabilities - Current Portion Other Current Liabilities $ 9.2 $ 0.3 $ 0.8 $ 0.1 Operating Lease Liabilities - Long-Term Other Long-Term Liabilities 47.5 0.2 24.3 0.4 Total Operating Lease Liabilities $ 56.7 $ 0.5 $ 25.1 $ 0.5 Finance Leases: Finance Lease Right-of-use-Assets, Net Property, Plant and Equipment, Net $ 8.8 $ 2.9 $ 3.5 $ 0.9 Finance Lease Liabilities Finance Lease Liabilities - Current Portion Other Current Liabilities $ 1.9 $ 1.5 $ — $ 0.1 Finance Lease Liabilities - Long-Term Other Long-Term Liabilities 9.1 2.7 4.5 0.8 Total Finance Lease Liabilities $ 11.0 $ 4.2 $ 4.5 $ 0.9
Other Information Related to Leases	Other information related to leases is as follows (in millions of dollars, unless otherwise noted): For the Three Months Ended March 31, 2019 Eversource CL&P NSTAR Electric PSNH Weighted-Average Remaining Lease Term (Years): Operating Leases 12 3 21 8 Financing Leases 11 3 23 10 Weighted-Average Discount Rate (Percentage): Operating Leases 3.8 % 3.2 % 4.1 % 3.6 % Financing Leases 4.5 % 10.5 % 2.9 % 3.5 % Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 2.9 $ 0.1 $ 0.3 $ — Operating Cash Flows from Finance Leases 0.3 0.2 0.1 — Financing Cash Flows from Finance Leases 0.4 0.3 — — Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 1.3 — — — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 1.3 — — —
Future Minimum Lease Payments under Long-Term Leases	Future minimum lease payments, excluding variable costs, under long-term leases, as of March 31, 2019 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH April 1, 2019 through December 31, 2019 $ 8.3 $ 0.2 $ 1.4 $ 0.1 $ 2.5 $ 1.5 $ 0.4 $ 0.1 Year Ending December 31, 2020 9.6 0.2 1.6 0.1 3.4 2.0 0.5 0.1 2021 8.7 — 1.6 0.1 2.9 1.5 0.5 0.1 2022 7.3 — 1.6 0.1 1.5 — 0.6 0.1 2023 4.8 — 1.6 0.1 0.7 — 0.6 0.1 2024 2.8 — 1.7 0.1 0.7 — 0.6 0.1 Thereafter 29.7 0.1 29.4 0.1 13.2 — 12.8 0.4 Future lease payments 71.2 0.5 38.9 0.7 24.9 5.0 16.0 1.0 Less amount representing interest 14.5 — 13.8 0.2 13.9 0.8 11.5 0.1 Present value of future minimum lease payments $ 56.7 $ 0.5 $ 25.1 $ 0.5 $ 11.0 $ 4.2 $ 4.5 $ 0.9
Future Minimum Lease Payments under Long-Term Leases	Future minimum lease payments, excluding variable costs, under long-term leases, as of March 31, 2019 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH April 1, 2019 through December 31, 2019 $ 8.3 $ 0.2 $ 1.4 $ 0.1 $ 2.5 $ 1.5 $ 0.4 $ 0.1 Year Ending December 31, 2020 9.6 0.2 1.6 0.1 3.4 2.0 0.5 0.1 2021 8.7 — 1.6 0.1 2.9 1.5 0.5 0.1 2022 7.3 — 1.6 0.1 1.5 — 0.6 0.1 2023 4.8 — 1.6 0.1 0.7 — 0.6 0.1 2024 2.8 — 1.7 0.1 0.7 — 0.6 0.1 Thereafter 29.7 0.1 29.4 0.1 13.2 — 12.8 0.4 Future lease payments 71.2 0.5 38.9 0.7 24.9 5.0 16.0 1.0 Less amount representing interest 14.5 — 13.8 0.2 13.9 0.8 11.5 0.1 Present value of future minimum lease payments $ 56.7 $ 0.5 $ 25.1 $ 0.5 $ 11.0 $ 4.2 $ 4.5 $ 0.9
Future Minimum Rental Payments under Operating Leases	At December 31, 2018, future minimum rental payments, excluding executory costs, such as property taxes, state use taxes, insurance, and maintenance were as follows: Operating Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2019 $ 11.5 $ 1.5 $ 7.2 $ 0.5 2020 9.8 1.4 6.0 0.4 2021 8.7 1.2 5.3 0.4 2022 7.2 1.1 4.4 0.4 2023 4.7 0.5 3.1 0.2 Thereafter 32.7 0.2 29.5 0.3 Future minimum lease payments $ 74.6 $ 5.9 $ 55.5 $ 2.2
Future Minimum Rental Payments under Capital Leases	Capital Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2019 $ 3.4 $ 2.0 $ 0.5 $ 0.1 2020 3.4 2.0 0.5 0.1 2021 2.9 1.5 0.5 0.1 2022 1.5 — 0.6 0.1 2023 0.7 — 0.6 0.1 Thereafter 13.9 — 13.4 0.5 Future minimum lease payments 25.8 5.5 16.1 1.0 Less amount representing interest 13.8 1.0 12.4 0.1 Present value of future minimum lease payments $ 12.0 $ 4.5 $ 3.7 $ 0.9

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Carrying Amounts and Estimated Fair Values of Financial Instruments	Carrying amounts and estimated fair values are as follows: Eversource CL&P NSTAR Electric PSNH (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value As of March 31, 2019: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 157.1 $ 116.2 $ 114.2 $ 43.0 $ 42.9 $ — $ — Long-Term Debt 13,089.8 13,519.6 3,265.8 3,538.0 2,945.2 3,107.3 805.3 831.1 Rate Reduction Bonds 604.9 623.3 — — — — 604.9 623.3 As of December 31, 2018: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 156.8 $ 116.2 $ 113.8 $ 43.0 $ 43.0 $ — $ — Long-Term Debt 13,086.1 13,154.9 3,254.0 3,429.2 2,944.8 3,024.1 805.2 819.5 Rate Reduction Bonds 635.7 645.8 — — — — 635.7 645.8

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income/(Loss) by Component, Net of Tax	The changes in accumulated other comprehensive income/(loss) by component, net of tax, are as follows: For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 Eversource (Millions of Dollars) Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Qualified Cash Flow Hedging Instruments Unrealized Losses on Marketable Securities Defined Benefit Plans Total Balance as of January 1st $ (4.4 ) $ (0.5 ) $ (55.1 ) $ (60.0 ) $ (6.2 ) $ — $ (60.2 ) $ (66.4 ) OCI Before Reclassifications — 0.7 — 0.7 — (0.4 ) — (0.4 ) Amounts Reclassified from AOCI 0.3 — 1.2 1.5 0.7 — 3.0 3.7 Net OCI 0.3 0.7 1.2 2.2 0.7 (0.4 ) 3.0 3.3 Balance as of March 31st $ (4.1 ) $ 0.2 $ (53.9 ) $ (57.8 ) $ (5.5 ) $ (0.4 ) $ (57.2 ) $ (63.1 )

COMMON SHARES (Tables)

COMMON SHARES (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Common Shares Authorized and Issued	The following table sets forth the Eversource parent common shares and the shares of common stock of CL&P, NSTAR Electric and PSNH that were authorized and issued, as well as the respective per share par values: Shares Authorized as of March 31, 2019 and December 31, 2018 Issued as of Par Value March 31, 2019 December 31, 2018 Eversource $ 5 380,000,000 333,878,402 333,878,402 CL&P $ 10 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 200 200 PSNH $ 1 100,000,000 301 301

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Components of Basic and Diluted EPS	The following table sets forth the components of basic and diluted EPS: Eversource (Millions of Dollars, except share information) For the Three Months Ended March 31, 2019 March 31, 2018 Net Income Attributable to Common Shareholders $ 308.7 $ 269.5 Weighted Average Common Shares Outstanding: Basic 317,624,593 317,397,052 Dilutive Effect 691,489 595,947 Diluted 318,316,082 317,992,999 Basic and Diluted EPS $ 0.97 $ 0.85

REVENUES (Tables)

REVENUES (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Operating Revenues Disaggregated by Revenue Source	The following tables present operating revenues disaggregated by revenue source: For the Three Months Ended March 31, 2019 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 1,033.3 $ 258.9 $ — $ 27.0 $ — $ — $ 1,319.2 Commercial 652.6 143.8 — 14.3 — (1.1 ) 809.6 Industrial 82.1 30.9 — 1.1 — (2.7 ) 111.4 Total Retail Tariff Sales Revenues 1,768.0 433.6 — 42.4 — (3.8 ) 2,240.2 Wholesale Transmission Revenues — — 324.9 — 13.5 (270.8 ) 67.6 Wholesale Market Sales Revenues 51.5 21.7 — 1.0 — — 74.2 Other Revenues from Contracts with Customers 12.6 0.9 3.2 1.7 244.6 (245.4 ) 17.6 Reserve for Revenues Subject to Refund (3.1 ) 1.6 — (0.8 ) — — (2.3 ) Total Revenues from Contracts with Customers 1,829.0 457.8 328.1 44.3 258.1 (520.0 ) 2,397.3 Alternative Revenue Programs 2.1 10.4 12.4 0.9 — (11.1 ) 14.7 Other Revenues (1) 2.8 0.7 — 0.3 — — 3.8 Total Operating Revenues $ 1,833.9 $ 468.9 $ 340.5 $ 45.5 $ 258.1 $ (531.1 ) $ 2,415.8 For the Three Months Ended March 31, 2018 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 994.4 $ 248.9 $ — $ 26.4 $ — $ — $ 1,269.7 Commercial 611.4 134.7 — 13.8 — — 759.9 Industrial 81.5 29.5 — 1.0 — (2.5 ) 109.5 Total Retail Tariff Sales Revenues 1,687.3 413.1 — 41.2 — (2.5 ) 2,139.1 Wholesale Transmission Revenues — — 313.6 — 10.1 (258.7 ) 65.0 Wholesale Market Sales Revenues 58.5 17.8 — 0.8 — — 77.1 Other Revenues from Contracts with Customers 16.0 (0.6 ) 3.1 4.0 220.8 (221.4 ) 21.9 Reserve for Revenues Subject to Refund (19.3 ) (4.5 ) — (2.2 ) — — (26.0 ) Total Revenues from Contracts with Customers 1,742.5 425.8 316.7 43.8 230.9 (482.6 ) 2,277.1 Alternative Revenue Programs 8.7 (1.7 ) (11.7 ) 0.7 — 10.6 6.6 Other Revenues 3.4 0.8 — 0.1 — — 4.3 Total Operating Revenues $ 1,754.6 $ 424.9 $ 305.0 $ 44.6 $ 230.9 $ (472.0 ) $ 2,288.0 For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2018 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Revenues from Contracts with Customers Retail Tariff Sales Residential $ 510.5 $ 371.0 $ 151.8 $ 483.4 $ 364.2 $ 146.8 Commercial 236.7 336.5 79.8 222.5 314.4 74.9 Industrial 34.6 28.8 18.7 35.8 28.1 17.6 Total Retail Tariff Sales Revenues 781.8 736.3 250.3 741.7 706.7 239.3 Wholesale Transmission Revenues 154.8 122.6 47.5 150.8 118.6 44.2 Wholesale Market Sales Revenues 13.7 24.4 13.4 10.3 24.9 24.1 Other Revenues from Contracts with Customers 8.9 4.0 3.6 7.5 8.3 3.5 Reserve for Revenues Subject to Refund — — (3.1 ) (12.5 ) (3.7 ) (3.1 ) Total Revenues from Contracts with Customers 959.2 887.3 311.7 897.8 854.8 308.0 Alternative Revenue Programs 5.7 7.3 1.5 (5.1 ) 6.7 (4.6 ) Other Revenues (1) 1.0 1.5 0.3 1.3 1.7 0.4 Eliminations (116.7 ) (98.5 ) (37.1 ) (109.0 ) (93.1 ) (36.4 ) Total Operating Revenues $ 849.2 $ 797.6 $ 276.4 $ 785.0 $ 770.1 $ 267.4 (1) Other Revenues include certain fees charged to customers, which are not considered revenue from contracts with customers. Other revenues also includes lease revenues under lessor accounting guidance of $1.0 million at Eversource, $0.2 million at CL&P, and $0.6 million at NSTAR Electric for the three months ended March 31, 2019.

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Summary of Segment Information and Segmented Total Assets	Eversource's segment information is as follows: For the Three Months Ended March 31, 2019 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 1,833.9 $ 468.9 $ 340.5 $ 45.5 $ 258.1 $ (531.1 ) $ 2,415.8 Depreciation and Amortization (179.2 ) (20.4 ) (61.5 ) (11.8 ) (13.6 ) 0.6 (285.9 ) Other Operating Expenses (1,475.6 ) (341.3 ) (98.8 ) (25.0 ) (225.5 ) 531.0 (1,635.2 ) Operating Income $ 179.1 $ 107.2 $ 180.2 $ 8.7 $ 19.0 $ 0.5 $ 494.7 Interest Expense $ (49.2 ) $ (11.7 ) $ (30.6 ) $ (8.6 ) $ (44.2 ) $ 12.6 $ (131.7 ) Other Income, Net 18.2 0.2 8.1 0.4 431.7 (427.6 ) 31.0 Net Income Attributable to Common Shareholders 120.1 76.5 118.2 0.9 407.5 (414.5 ) 308.7 Cash Flows Used for Investments in Plant 279.3 87.4 231.4 20.7 55.9 — 674.7 For the Three Months Ended March 31, 2018 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 1,754.6 $ 424.9 $ 305.0 $ 44.6 $ 230.9 $ (472.0 ) $ 2,288.0 Depreciation and Amortization (144.4 ) (26.4 ) (56.6 ) (10.7 ) (12.0 ) 0.6 (249.5 ) Other Operating Expenses (1,443.5 ) (312.6 ) (83.2 ) (23.9 ) (204.7 ) 471.9 (1,596.0 ) Operating Income $ 166.7 $ 85.9 $ 165.2 $ 10.0 $ 14.2 $ 0.5 $ 442.5 Interest Expense $ (47.4 ) $ (11.1 ) $ (29.7 ) $ (8.4 ) $ (31.9 ) $ 7.4 $ (121.1 ) Other Income/(Loss), Net 19.6 2.0 8.0 (0.6 ) 360.1 (355.3 ) 33.8 Net Income Attributable to Common Shareholders 104.2 57.8 107.4 1.5 346.0 (347.4 ) 269.5 Cash Flows Used for Investments in Plant 236.0 70.4 239.2 19.0 42.7 — 607.3 The following table summarizes Eversource's segmented total assets: Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Water Distribution Other Eliminations Total As of March 31, 2019 $ 21,507.0 $ 4,019.1 $ 10,533.4 $ 2,268.3 $ 18,939.8 $ (18,326.6 ) $ 38,941.0 As of December 31, 2018 21,389.1 3,904.9 10,285.0 2,253.0 17,874.2 (17,464.9 ) 38,241.3

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) customer in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)customerutilityMW	Mar. 31, 2018USD ($)	Feb. 08, 2019USD ($)mi²	Jan. 01, 2019USD ($)
Summary of Accounting Policies [Line Items]
Number of electric, natural gas and water customers | customer	4
Operating lease liability	$ 56.7
Operating lease right-of-use assets	56.7
Energy efficiency funds collected from customers to be remitted to the State of Connecticut	$ 10.7	$ 12.7
Northern Pass
Summary of Accounting Policies [Line Items]
Capacity required for transmission line | MW	1,090
Captialized costs for the NPT project	$ 311
Revolution Wind and South Fork Wind
Summary of Accounting Policies [Line Items]
Cost of investment in unconsolidated affiliate			$ 225
Ownership interest			50.00%
Area of land | mi²			257
ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability				$ 58
Operating lease right-of-use assets				58
NSTAR Electric
Summary of Accounting Policies [Line Items]
Operating lease liability	25.1
Operating lease right-of-use assets	25.1
NSTAR Electric | ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability				25.3
Operating lease right-of-use assets				25.3
CL&P
Summary of Accounting Policies [Line Items]
Operating lease liability	0.5
Operating lease right-of-use assets	$ 0.5
Period of accounts receivable recoverable under financial or medical duress	180 days
CL&P | ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability				0.6
Operating lease right-of-use assets				0.6
PSNH
Summary of Accounting Policies [Line Items]
Operating lease liability	$ 0.5
Operating lease right-of-use assets	$ 0.5
PSNH | ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability				0.6
Operating lease right-of-use assets				$ 0.6
Yankee Gas
Summary of Accounting Policies [Line Items]
Period of accounts receivable recoverable under financial or medical duress	90 days
Connecticut, Massachusetts and New Hampshire
Summary of Accounting Policies [Line Items]
Number of regulated utilities | utility	8

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for Uncollectible Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total provision for uncollectible accounts	$ 223,300		$ 212,700
Provision for uncollectible hardship accounts	134,600		131,500
Bad debt expense associated with accounts receivable	18,565	$ 19,613
CL&P
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total provision for uncollectible accounts	93,000		88,000
Provision for uncollectible hardship accounts	75,200		71,900
Bad debt expense associated with accounts receivable	4,116	3,912
NSTAR Electric
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total provision for uncollectible accounts	74,800		74,500
Provision for uncollectible hardship accounts	40,900		42,500
Bad debt expense associated with accounts receivable	5,953	7,526
PSNH
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total provision for uncollectible accounts	11,000		11,100
Provision for uncollectible hardship accounts	0		$ 0
Bad debt expense associated with accounts receivable	$ 1,700	$ 1,700

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Components of Other Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Summary of Accounting Policies [Line Items]
Other Income, Net	$ 30,985	$ 33,789
Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other Income, Net	7,400	15,200
AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	10,900	9,700
Equity in Earnings
Summary of Accounting Policies [Line Items]
Other Income, Net	5,000	4,600
Investment Income
Summary of Accounting Policies [Line Items]
Other Income, Net	1,200	700
Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	6,500	3,500
Other
Summary of Accounting Policies [Line Items]
Other Income, Net	0	100
CL&P
Summary of Accounting Policies [Line Items]
Other Income, Net	3,880	6,560
CL&P | Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other Income, Net	(600)	3,000
CL&P | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	2,600	2,800
CL&P | Equity in Earnings
Summary of Accounting Policies [Line Items]
Other Income, Net	0	0
CL&P | Investment Income
Summary of Accounting Policies [Line Items]
Other Income, Net	1,700	(100)
CL&P | Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	400	900
CL&P | Other
Summary of Accounting Policies [Line Items]
Other Income, Net	(200)	0
NSTAR Electric
Summary of Accounting Policies [Line Items]
Other Income, Net	11,086	12,601
NSTAR Electric | Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other Income, Net	7,000	8,400
NSTAR Electric | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	4,000	3,400
NSTAR Electric | Equity in Earnings
Summary of Accounting Policies [Line Items]
Other Income, Net	200	0
NSTAR Electric | Investment Income
Summary of Accounting Policies [Line Items]
Other Income, Net	(300)	600
NSTAR Electric | Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	200	200
NSTAR Electric | Other
Summary of Accounting Policies [Line Items]
Other Income, Net	0	0
PSNH
Summary of Accounting Policies [Line Items]
Other Income, Net	7,022	4,749
PSNH | Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other Income, Net	500	2,300
PSNH | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	200	0
PSNH | Equity in Earnings
Summary of Accounting Policies [Line Items]
Other Income, Net	0	0
PSNH | Investment Income
Summary of Accounting Policies [Line Items]
Other Income, Net	400	0
PSNH | Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	5,900	2,400
PSNH | Other
Summary of Accounting Policies [Line Items]
Other Income, Net	$ 0	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Schedule of Gross Tax Receipts [Line Items]
Gross receipts taxes	$ 45	$ 43.4
CL&P
Schedule of Gross Tax Receipts [Line Items]
Gross receipts taxes	$ 36.2	$ 35.6

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Non-cash Investing Activities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	$ 336.3	$ 274.4
CL&P
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	121.9	117.7
NSTAR Electric
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	83.2	59.5
PSNH
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	$ 30.4	$ 36

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reconciliation of Cash Balances to Cash and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	$ 35,145	$ 108,068
Cash and Restricted Cash reported on the Statements of Cash Flows	108,372	209,324	$ 362,615	$ 85,890
Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	45,900	72,100
Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	24,200	25,900
Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	3,200	3,200
CL&P
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	7,496	87,721
Cash and Restricted Cash reported on the Statements of Cash Flows	11,404	91,613	243,839	9,619
CL&P | Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	3,600	3,500
CL&P | Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	300	400
CL&P | Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	0
NSTAR Electric
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	1,769	1,606
Cash and Restricted Cash reported on the Statements of Cash Flows	14,905	14,659	22,465	14,708
NSTAR Electric | Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	13,000	13,000
NSTAR Electric | Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	100	100
NSTAR Electric | Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	0
PSNH
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	3,961	1,439
Cash and Restricted Cash reported on the Statements of Cash Flows	28,796	52,723	$ 15,253	$ 2,191
PSNH | Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	21,100	47,500
PSNH | Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	500	600
PSNH | Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 3,200	$ 3,200

REGULATORY ACCOUNTING - Compone

REGULATORY ACCOUNTING - Components of Regulatory Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 5,096,700	$ 5,145,900
Less: Current Portion	507,255	514,779
Total Long-Term Regulatory Assets	4,589,427	4,631,137
Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	1,878,700	1,914,800
Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	730,900	728,600
Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	597,700	608,400
Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	579,000	576,000
Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	317,700	316,000
Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	353,500	356,500
Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	344,200	348,400
Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	92,800	89,200
Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	202,200	208,000
CL&P
Regulatory Assets [Line Items]
Total Regulatory Assets	1,644,400	1,630,700
Less: Current Portion	147,712	125,155
Total Long-Term Regulatory Assets	1,496,679	1,505,488
CL&P | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	416,000	424,700
CL&P | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	454,300	454,400
CL&P | Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
CL&P | Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	307,400	302,600
CL&P | Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	54,400	33,200
CL&P | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	353,100	356,500
CL&P | Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
CL&P | Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	32,800	32,300
CL&P | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	26,400	27,000
NSTAR Electric
Regulatory Assets [Line Items]
Total Regulatory Assets	1,408,600	1,438,200
Less: Current Portion	234,662	241,747
Total Long-Term Regulatory Assets	1,173,851	1,196,512
NSTAR Electric | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	534,900	544,400
NSTAR Electric | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	106,100	105,900
NSTAR Electric | Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric | Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	204,400	212,900
NSTAR Electric | Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	160,200	169,100
NSTAR Electric | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric | Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	295,500	299,100
NSTAR Electric | Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	44,900	42,200
NSTAR Electric | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	62,600	64,600
PSNH
Regulatory Assets [Line Items]
Total Regulatory Assets	932,000	929,500
Less: Current Portion	76,599	67,228
Total Long-Term Regulatory Assets	855,369	862,288
PSNH | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	165,800	169,600
PSNH | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	8,000	8,300
PSNH | Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	597,700	608,400
PSNH | Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	67,200	60,500
PSNH | Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	78,000	67,300
PSNH | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH | Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH | Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	3,400	3,300
PSNH | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 11,900	$ 12,100

REGULATORY ACCOUNTING - Narrati

REGULATORY ACCOUNTING - Narrative (Details) - USD ($) $ in Thousands	May 01, 2019	Mar. 31, 2019	Mar. 31, 2018	Apr. 17, 2019	Mar. 26, 2019	Dec. 31, 2018	Nov. 16, 2018
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved		$ 129,500				$ 122,900
Regulatory assets		5,096,700				5,145,900
Other income, net		30,985	$ 33,789
PSNH
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved		13,900				12,200
Regulatory assets		932,000				929,500
Other income, net		7,022	4,749
CL&P
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved		41,900				42,100
Regulatory assets		1,644,400				1,630,700
Other income, net		3,880	6,560
NSTAR Electric
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved		52,800				49,300
Regulatory assets		1,408,600				$ 1,438,200
Other income, net		11,086	$ 12,601
Storm Costs | PSNH
Regulatory Assets [Line Items]
Regulatory assets					$ 38,100
Storm Costs | CL&P
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved		145,500					$ 153,000
Storm Costs | CL&P | Subsequent Event
Regulatory Assets [Line Items]
Regulatory assets				$ 141,000
Recovery period	6 years
Deferred Costs from Generation Asset Sale | PSNH
Regulatory Assets [Line Items]
Other income, net		$ 5,200

REGULATORY ACCOUNTING - Compo_2

REGULATORY ACCOUNTING - Components of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 4,012,800	$ 3,979,700
Less: Current Portion	385,442	370,230
Total Long-Term Regulatory Liabilities	3,627,389	3,609,475
EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	2,871,400	2,883,000
Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	535,000	521,000
Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	87,200	91,200
Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	332,500	309,000
AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	71,400	70,700
Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	27,000	24,600
Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	88,300	80,200
CL&P
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,232,800	1,231,800
Less: Current Portion	106,489	109,614
Total Long-Term Regulatory Liabilities	1,126,279	1,122,157
CL&P | EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,030,700	1,031,000
CL&P | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	46,200	39,900
CL&P | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
CL&P | Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	79,500	89,500
CL&P | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	47,100	47,400
CL&P | Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
CL&P | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	29,300	24,000
NSTAR Electric
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,708,600	1,703,900
Less: Current Portion	193,959	190,620
Total Long-Term Regulatory Liabilities	1,514,557	1,513,279
NSTAR Electric | EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,096,700	1,103,700
NSTAR Electric | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	313,400	307,100
NSTAR Electric | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	73,600	76,900
NSTAR Electric | Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	166,700	163,700
NSTAR Electric | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	24,300	23,300
NSTAR Electric | Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
NSTAR Electric | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	33,900	29,200
PSNH
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	475,600	483,600
Less: Current Portion	45,655	55,526
Total Long-Term Regulatory Liabilities	429,932	428,069
PSNH | EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	394,600	396,400
PSNH | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	22,100	22,100
PSNH | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH | Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	39,900	48,300
PSNH | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH | Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	15,800	12,600
PSNH | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 3,200	$ 4,200

PROPERTY, PLANT AND EQUIPMENT_3

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	$ 15,245,900	$ 15,071,100
Distribution - Natural Gas	3,635,600	3,546,200
Transmission - Electric	10,251,100	10,153,900
Distribution - Water	1,649,500	1,639,800
Solar	169,900	164,100
Utility	30,952,000	30,575,100
Other	798,300	778,600
Property, Plant and Equipment, Gross	31,750,300	31,353,700
Less: Accumulated Depreciation
Utility	(7,229,500)	(7,126,200)
Other	(348,700)	(336,700)
Total Accumulated Depreciation	(7,578,200)	(7,462,900)
Property, Plant and Equipment, Net	24,172,100	23,890,800
Construction Work in Progress	1,860,700	1,719,600
Net Plant	26,032,781	25,610,428
CL&P
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	6,255,800	6,176,400
Transmission - Electric	4,746,400	4,700,500
Solar	0	0
Property, Plant and Equipment, Gross	11,002,200	10,876,900
Less: Accumulated Depreciation
Total Accumulated Depreciation	(2,328,000)	(2,302,600)
Property, Plant and Equipment, Net	8,674,200	8,574,300
Construction Work in Progress	391,700	335,400
Net Plant	9,065,880	8,909,701
NSTAR Electric
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	6,828,500	6,756,400
Transmission - Electric	4,085,600	4,065,900
Solar	169,900	164,100
Property, Plant and Equipment, Gross	11,084,000	10,986,400
Less: Accumulated Depreciation
Total Accumulated Depreciation	(2,749,900)	(2,702,000)
Property, Plant and Equipment, Net	8,334,100	8,284,400
Construction Work in Progress	581,500	510,300
Net Plant	8,915,608	8,794,700
PSNH
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	2,201,800	2,178,600
Transmission - Electric	1,370,200	1,338,700
Solar	0	0
Property, Plant and Equipment, Gross	3,572,000	3,517,300
Less: Accumulated Depreciation
Total Accumulated Depreciation	(789,300)	(772,900)
Property, Plant and Equipment, Net	2,782,700	2,744,400
Construction Work in Progress	137,900	135,700
Net Plant	$ 2,920,560	$ 2,880,073

DERIVATIVE INSTRUMENTS - Gross

DERIVATIVE INSTRUMENTS - Gross Fair Values and Net Amounts of Contracts (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current Derivative Assets | CL&P | Level 3
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	$ 10.4	$ 9.6
Netting	(1.9)	(3.4)
Net Amount Recorded as a Derivative	8.5	6.2
Current Derivative Assets | Other | Level 2
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	0	1.5
Netting	0	(0.9)
Net Amount Recorded as a Derivative	0	0.6
Long-term Derivative Assets | CL&P | Level 3
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	73.1	74.2
Netting	(2.2)	(2.3)
Net Amount Recorded as a Derivative	70.9	71.9
Current Derivative Liabilities | CL&P | Level 3
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(59.7)	(55.1)
Netting	0	0
Net Amount Recorded as a Derivative	(59.7)	(55.1)
Current Derivative Liabilities | Other | Level 2
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(0.4)	0
Netting	0.2	0
Net Amount Recorded as a Derivative	(0.2)	0
Long-Term Derivative Liabilities | CL&P | Level 3
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(372.8)	(379.5)
Netting	0	0
Net Amount Recorded as a Derivative	(372.8)	(379.5)
Long-Term Derivative Liabilities | Other | Level 2
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(0.2)	0
Netting	0	0
Net Amount Recorded as a Derivative	$ (0.2)	$ 0

DERIVATIVE INSTRUMENTS - Narrat

DERIVATIVE INSTRUMENTS - Narrative (Details) MWh in Millions, MMBTU in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)MMBTUMWhMW	Mar. 31, 2018USD ($)	Dec. 31, 2018MMBTU
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 (in MW) | MW	787
Amount of natural gas to be purchased under futures contracts | MMBTU	6.2		12.5
Gains (losses) on deferred as regulatory costs | $	$ (5.2)	$ (36.1)
Level 3 | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts	3.70%
Level 3 | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts	15.10%
CL&P
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 (mwh) | MWh	0.1

DERIVATIVE INSTRUMENTS - Summar

DERIVATIVE INSTRUMENTS - Summary of Level 3 Derivative Contracts and Significant Observable Inputs Used (Details) - CL&P - Level 3 - $ / KWmo	Mar. 31, 2019	Dec. 31, 2018
Capacity Prices | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	4.30	4.30
Capacity Prices | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	7.34	7.44
Forward Reserve | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	0.75	0.75
Forward Reserve | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	1.78	1.78

DERIVATIVE INSTRUMENTS - Change

DERIVATIVE INSTRUMENTS - Changes in the Level 3 Category of Derivative Assets Measured at Fair Value on a Recurring Basis (Details) - CL&P - Level 3 - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivatives, Net [Rollforward]
Fair Value as of Beginning of Period	$ (356.5)	$ (362.3)
Net Realized/Unrealized Losses Included in Regulatory Assets	(5.3)	(36.9)
Settlements	8.7	12.7
Fair Value as of End of Period	$ (353.1)	$ (386.5)

MARKETABLE SECURITIES - Narrati

MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	$ 49.6		$ 44
Unrealized gains recorded in other income	1
Unrealized losses recorded in other income		$ 0.7
CYAPC and YAEC
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	166.6		200
Marketable securities held in nuclear decommissioning trust	$ 170.7		$ 143.9

MARKETABLE SECURITIES - Summary

MARKETABLE SECURITIES - Summary of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Amortized Cost	$ 212.3	$ 190
Pre-Tax Unrealized Gains	0.9	0.4
Pre-Tax Unrealized Losses	(0.9)	(4)
Fair Value	$ 212.3	$ 186.4

MARKETABLE SECURITIES - Contrac

MARKETABLE SECURITIES - Contractual Maturities of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Amortized Cost
Less than one year	$ 29.7
One to five years	48.5
Six to ten years	39
Greater than ten years	95.1
Amortized Cost	212.3	$ 190
Fair Value
Less than one year	29.6
One to five years	48.5
Six to ten years	39.4
Greater than ten years	94.8
Fair Value	$ 212.3	$ 186.4

MARKETABLE SECURITIES - Marketa

MARKETABLE SECURITIES - Marketable Securities Recorded at Fair Value on a Recurring Basis by Level (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 428.5	$ 430.4
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	240.4	269.9
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	188.1	160.5
Mutual Funds and Equities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	216.2	244
Money Market Funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	24.2	25.9
U.S. Government Issued Debt Securities (Agency and Treasury) | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	104.3	79.6
Corporate Debt Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	44.7	39.5
Asset-Backed Debt Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	13.9	14
Municipal Bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	16	19.2
Other Fixed Income Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 9.2	$ 8.2

SHORT-TERM AND LONG-TERM DEBT -

SHORT-TERM AND LONG-TERM DEBT - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
CL&P
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	$ 261,600,000
PSNH
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	61,000,000	$ 57,000,000
HEEC
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	22,300,000
Commercial Paper | NSTAR Electric
Line of Credit Facility [Line Items]
Maximum borrowing capacity	650,000,000
Line of Credit
Line of Credit Facility [Line Items]
Amount outstanding under line of credit	0	0
Line of Credit | NSTAR Electric
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 650,000,000
Debt instrument term	5 years
Line of Credit | Aquarion
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 100,000,000
Amount outstanding under line of credit	0	$ 0
Eversource Parent | Commercial Paper
Line of Credit Facility [Line Items]
Maximum borrowing capacity	1,450,000,000
Commercial paper borrowings	261,600,000
Eversource Parent | Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 1,450,000,000
Debt instrument term	5 years

SHORT-TERM AND LONG-TERM DEBT_2

SHORT-TERM AND LONG-TERM DEBT - Borrowings Outstanding and Available under the Commercial Paper Programs (Details) - Commercial Paper - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Borrowings outstanding	$ 1,371	$ 631.5
Available borrowing capacity	$ 79	$ 818.5
Weighted-average interest rate	2.69%	2.77%
NSTAR Electric
Debt Instrument [Line Items]
Borrowings outstanding	$ 368.4	$ 278.5
Available borrowing capacity	$ 281.6	$ 371.5
Weighted-average interest rate	2.49%	2.50%

SHORT-TERM AND LONG-TERM DEBT_3

SHORT-TERM AND LONG-TERM DEBT - Summary of Long-Term Debt Issuance and Repayments (Details) - USD ($) $ in Thousands	Feb. 01, 2019	Apr. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Feb. 01, 2009
Debt Instrument [Line Items]
Repayments			$ (250,215)	$ (150,218)
CL&P
Debt Instrument [Line Items]
Repayments			(250,000)	$ 0
CL&P | Senior Notes | 4.00% 2018 Series A First Mortgage Bonds | Subsequent Event
Debt Instrument [Line Items]
Issuances		$ 300,000
Interest rate, stated percentage		4.00%
CL&P | Senior Notes | 4.00% 2018 Series A First Mortgage Bonds | Eversource Parent
Debt Instrument [Line Items]
Long-term debt			$ 800,000
CL&P | Senior Notes | 5.50% 2009 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Repayments	$ (250,000)
Interest rate, stated percentage					5.65%

RATE REDUCTION BONDS AND VARI_3

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Narrative (Details) - PSNH - Rate Reduction Bonds	May 08, 2018USD ($)
Debt Instrument [Line Items]
Amount of securitized rate reduction bonds issued	$ 635,700,000
Weighted average interest rate	3.66%

RATE REDUCTION BONDS AND VARI_4

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Summary of the Impact of Funding on the Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Assets	$ 5,096,700	$ 5,145,900
Regulatory Liabilities	3,627,389	3,609,475
Accrued Interest (included in Other Current Liabilities)	840,587	823,006
Rate Reduction Bonds - Current Portion	43,210	52,332
Rate Reduction Bonds - Long-Term Portion	561,727	583,331
Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Assets	597,700	608,400
Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Assets	202,200	208,000
Prepayments and Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	45,900	72,100
Long-term Derivative Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	3,200	3,200
PSNH
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Assets	932,000	929,500
Regulatory Liabilities	429,932	428,069
Accrued Interest (included in Other Current Liabilities)	55,088	64,046
Rate Reduction Bonds - Current Portion	43,210	52,332
Rate Reduction Bonds - Long-Term Portion	561,727	583,331
PSNH | Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Assets	597,700	608,400
PSNH | Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Assets	11,900	12,100
PSNH | Prepayments and Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	21,100	47,500
PSNH | Long-term Derivative Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	3,200	3,200
PSNH | VIE
Condensed Balance Sheet Statements, Captions [Line Items]
Rate Reduction Bonds - Current Portion	43,200	52,300
Rate Reduction Bonds - Long-Term Portion	561,700	583,300
PSNH | VIE | Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Assets	597,700	608,400
PSNH | VIE | Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Liabilities	10,000	5,800
Accrued Interest (included in Other Current Liabilities)	3,500	14,400
PSNH | VIE | Prepayments and Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	21,100	47,500
PSNH | VIE | Long-term Derivative Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	$ 3,200	$ 3,200

RATE REDUCTION BONDS AND VARI_5

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Summary of the Impact of Funding on the Income Statements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 131,734	$ 121,129
PSNH
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	14,367	12,772
PSNH | VIE | Rate Reduction Bonds
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	10,600	0
Interest Expense on RRB Principal (included in Interest Expense)	$ 5,400	$ 0

PENSION BENEFITS AND POSTRETI_3

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	$ 19.3	$ 22.7
Interest Cost	54.2	48.4
Expected Return on Pension Plan Assets	(92.3)	(98)
Actuarial Loss	35.8	36
Prior Service Cost/(Credit)	1.1	2.2
Total Net Periodic Benefit Expense	18.1	11.3
PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	2.1	2.7
Interest Cost	8.1	7.6
Expected Return on Pension Plan Assets	(16.6)	(18.1)
Actuarial Loss	2.5	2.6
Prior Service Cost/(Credit)	(5.8)	(5.9)
Total Net Periodic Benefit Expense	(9.7)	(11.1)
CL&P | Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	4.8	5.7
Interest Cost	11.5	10.6
Expected Return on Pension Plan Assets	(18.8)	(20.8)
Actuarial Loss	8.1	7.4
Prior Service Cost/(Credit)	0	0.4
Total Net Periodic Benefit Expense	5.6	3.3
Intercompany Allocations	7.8	1.4
CL&P | PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.4	0.5
Interest Cost	1.5	1.4
Expected Return on Pension Plan Assets	(2.3)	(2.6)
Actuarial Loss	0.4	0.3
Prior Service Cost/(Credit)	0.3	0.3
Total Net Periodic Benefit Expense	0.3	(0.1)
Intercompany Allocations	(0.1)	(0.3)
NSTAR Electric | Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	3.9	4.7
Interest Cost	11.9	10.8
Expected Return on Pension Plan Assets	(24.4)	(25.2)
Actuarial Loss	9.4	10.5
Prior Service Cost/(Credit)	0.1	0.2
Total Net Periodic Benefit Expense	0.9	1
Intercompany Allocations	3	1.5
NSTAR Electric | PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.4	0.5
Interest Cost	2.3	2.2
Expected Return on Pension Plan Assets	(7.5)	(8.1)
Actuarial Loss	0.9	0.7
Prior Service Cost/(Credit)	(4.2)	(4.3)
Total Net Periodic Benefit Expense	(8.1)	(9)
Intercompany Allocations	(0.2)	(0.3)
PSNH | Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	2.6	2.9
Interest Cost	6.2	5.3
Expected Return on Pension Plan Assets	(10.3)	(10.9)
Actuarial Loss	3.5	3.3
Prior Service Cost/(Credit)	0	0.1
Total Net Periodic Benefit Expense	2	0.7
Intercompany Allocations	2.4	0.5
PSNH | PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.2	0.3
Interest Cost	0.9	0.8
Expected Return on Pension Plan Assets	(1.3)	(1.5)
Actuarial Loss	0.2	0.2
Prior Service Cost/(Credit)	0.1	0.1
Total Net Periodic Benefit Expense	0.1	(0.1)
Intercompany Allocations	$ (0.1)	$ (0.1)

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Environmental Sites and Related Reserves (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019USD ($)site	Dec. 31, 2018USD ($)site
Site Contingency [Line Items]
Number of Sites | site	59	60
Reserve | $	$ 64.8	$ 64.7
CL&P
Site Contingency [Line Items]
Number of Sites | site	15	15
Reserve | $	$ 5.6	$ 5.4
NSTAR Electric
Site Contingency [Line Items]
Number of Sites | site	15	16
Reserve | $	$ 10.5	$ 10.9
PSNH
Site Contingency [Line Items]
Number of Sites | site	9	9
Reserve | $	$ 5.3	$ 5.4

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Environmental Matters (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Site Contingency [Line Items]
Reserve balance	$ 64.8	$ 64.7
MGP Sites
Site Contingency [Line Items]
Reserve balance	$ 50.6	$ 50.1

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Long-Term Contractual Arrangements (Details) - Milestone Nuclear Power Station MWh in Millions	Mar. 15, 2019megawatt	Dec. 28, 2018MWh
Long-term Purchase Commitment [Line Items]
Annual purchase requirement (in MWh) | MWh		9
Percent of the facility's output required to be purchased	50.00%
Nameplate capacity (in megawatts) | megawatt	2,112
CL&P
Long-term Purchase Commitment [Line Items]
Contract term	10 years	10 years
Percent of the facility's output required to be purchased	40.00%
UI
Long-term Purchase Commitment [Line Items]
Contract term	10 years	10 years

COMMITMENTS AND CONTINGENCIES_4

COMMITMENTS AND CONTINGENCIES - Guarantees and Indemnifications (Details)	Mar. 31, 2019USD ($)
Eversource Gas Transmission LLC
Guarantor Obligations [Line Items]
Capital contribution guaranty	$ 184,800,000
Guarantee of Financial Obligations of NPT
Guarantor Obligations [Line Items]
Maximum exposure (up to)	25,000,000
Guarantee of NPT Letters of Credit
Guarantor Obligations [Line Items]
Maximum exposure (up to)	$ 14,000,000

COMMITMENTS AND CONTINGENCIES_5

COMMITMENTS AND CONTINGENCIES - Summary of Exposure to Guaruantees and Indemnifications (Details) $ in Millions	Mar. 31, 2019USD ($)
Eversource Investment LLC - Declining Balance Guarantee for Revolution Wind and South Fork Wind
Loss Contingencies [Line Items]
Maximum exposure	$ 113.9
Various - Surety Bonds
Loss Contingencies [Line Items]
Maximum exposure	32
Rocky River Realty Company and Eversource Service - Lease Payments for Real Estate
Loss Contingencies [Line Items]
Maximum exposure	7.3
Bay State Wind LLC - Real Estate Purchase
Loss Contingencies [Line Items]
Maximum exposure	$ 2.5

COMMITMENTS AND CONTINGENCIES_6

COMMITMENTS AND CONTINGENCIES - Spent Nuclear Fuel Obligations - Yankee Companies (Details) - USD ($) $ in Millions	Feb. 21, 2019	May 22, 2017
Loss Contingencies [Line Items]
Remaining damages sought	$ 1.2
CYAPC, YAEC, and MYAPC
Loss Contingencies [Line Items]
Damages sought		$ 104.4
Damages awarded	103.2
CYAPC
Loss Contingencies [Line Items]
Damages awarded	40.7
YAEC
Loss Contingencies [Line Items]
Damages awarded	28.1
MYAPC
Loss Contingencies [Line Items]
Damages awarded	$ 34.4

COMMITMENTS AND CONTINGENCIES_7

COMMITMENTS AND CONTINGENCIES - FERC ROE Complaints (Details) - USD ($) $ in Millions	Apr. 29, 2016	Oct. 16, 2014	Mar. 31, 2019	Mar. 26, 2014	Oct. 15, 2014
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified			10.41%
Percentage of incentive cap on total ROE			13.08%
Minimum
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified			9.60%
Maximum
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified			10.99%
FERC ROE First, Second and Third Complaints
Loss Contingencies [Line Items]
Base ROE subsequently authorized			11.14%
FERC ROE First, Second and Third Complaints | Minimum
Loss Contingencies [Line Items]
Percentage of maximum ROE for any incentive project					11.14%
FERC ROE First, Second and Third Complaints | Maximum
Loss Contingencies [Line Items]
Percentage of maximum ROE for any incentive project					13.10%
FERC ROE Complaints
Loss Contingencies [Line Items]
Period of complaint			15 months
Basis point change			0.10%
Estimate of possible loss for each 10 basis point change to base ROE			$ 3
FERC ROE Fourth Complaint
Loss Contingencies [Line Items]
Base ROE percentage of complaint period	10.57%
Maximum percentage cap of ROE for incentive projects	11.74%
FERC ROE First Complaint
Loss Contingencies [Line Items]
Base ROE subsequently authorized		10.57%
Percentage of maximum ROE for any incentive project		11.74%
Amounts associated with first complaint refunded			38.9
FERC ROE First Complaint | CL&P
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded			22.4
FERC ROE First Complaint | NSTAR Electric
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded			13.7
FERC ROE First Complaint | PSNH
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded			2.8
FERC ROE Second Complaint
Loss Contingencies [Line Items]
Base ROE percentage of complaint period				10.57%
Percentage of maximum ROE for any incentive project				11.74%
Loss contingency, estimate of possible earnings impact			39.1
FERC ROE Second Complaint | CL&P
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			21.4
FERC ROE Second Complaint | NSTAR Electric
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			14.6
FERC ROE Second Complaint | PSNH
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			$ 3.1

COMMITMENTS AND CONTINGENCIES_8

COMMITMENTS AND CONTINGENCIES - Eversource and NSTAR Electric Boston Harbor Civil Action (Details) $ in Millions	Jul. 15, 2016kV	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Loss Contingencies [Line Items]
Amount of capacity required for installation of distribution cable (in kV) | kV	115
NSTAR Electric
Loss Contingencies [Line Items]
Base rate credit for new cable | $		$ 17.5	$ 17.5

LEASES - Narrative (Details)

LEASES - Narrative (Details)	3 Months Ended
	Mar. 31, 2019
Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
CL&P | Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
CL&P | Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
NSTAR Electric | Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
NSTAR Electric | Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
PSNH | Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
PSNH | Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years

LEASES - Components of Lease Co

LEASES - Components of Lease Cost (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Financing Lease Cost:
Amortization of Right-of-use-Assets	$ 0.4
Interest on Lease Liabilities	0.3
Total Finance Lease Cost	0.7
Operating Lease Cost	3
Variable Lease Cost	15.5
Total Lease Cost	19.2
CL&P
Financing Lease Cost:
Amortization of Right-of-use-Assets	0.2
Interest on Lease Liabilities	0.1
Total Finance Lease Cost	0.3
Operating Lease Cost	0.1
Variable Lease Cost	3.5
Total Lease Cost	3.9
NSTAR Electric
Financing Lease Cost:
Amortization of Right-of-use-Assets	0
Interest on Lease Liabilities	0.3
Total Finance Lease Cost	0.3
Operating Lease Cost	0.5
Variable Lease Cost	0
Total Lease Cost	0.8
PSNH
Financing Lease Cost:
Amortization of Right-of-use-Assets	0
Interest on Lease Liabilities	0
Total Finance Lease Cost	0
Operating Lease Cost	0
Variable Lease Cost	12
Total Lease Cost	$ 12

LEASES - Supplemental Balance S

LEASES - Supplemental Balance Sheet Information Related to Leases (Details) $ in Millions	Mar. 31, 2019USD ($)
Operating Leases:
Operating Lease Right-of-use-Assets, Net	$ 56.7
Operating Lease Liabilities - Current Portion	9.2
Operating Lease Liabilities - Long-Term	47.5
Total Operating Lease Liabilities	56.7
Finance Leases:
Finance Lease Right-of-use-Assets, Net	8.8
Finance Lease Liabilities - Current Portion	1.9
Finance Lease Liabilities - Long-Term	9.1
Total Finance Lease Liabilities	11
CL&P
Operating Leases:
Operating Lease Right-of-use-Assets, Net	0.5
Operating Lease Liabilities - Current Portion	0.3
Operating Lease Liabilities - Long-Term	0.2
Total Operating Lease Liabilities	0.5
Finance Leases:
Finance Lease Right-of-use-Assets, Net	2.9
Finance Lease Liabilities - Current Portion	1.5
Finance Lease Liabilities - Long-Term	2.7
Total Finance Lease Liabilities	4.2
NSTAR Electric
Operating Leases:
Operating Lease Right-of-use-Assets, Net	25.1
Operating Lease Liabilities - Current Portion	0.8
Operating Lease Liabilities - Long-Term	24.3
Total Operating Lease Liabilities	25.1
Finance Leases:
Finance Lease Right-of-use-Assets, Net	3.5
Finance Lease Liabilities - Current Portion	0
Finance Lease Liabilities - Long-Term	4.5
Total Finance Lease Liabilities	4.5
PSNH
Operating Leases:
Operating Lease Right-of-use-Assets, Net	0.5
Operating Lease Liabilities - Current Portion	0.1
Operating Lease Liabilities - Long-Term	0.4
Total Operating Lease Liabilities	0.5
Finance Leases:
Finance Lease Right-of-use-Assets, Net	0.9
Finance Lease Liabilities - Current Portion	0.1
Finance Lease Liabilities - Long-Term	0.8
Total Finance Lease Liabilities	$ 0.9

LEASES - Other Information Rela

LEASES - Other Information Related to Leases (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Weighted-Average Remaining Lease Term:
Operating Leases	12 years
Financing Leases	11 years
Weighted-Average Discount Rate:
Operating Leases	3.80%
Financing Leases	4.50%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 2.9
Operating Cash Flows from Finance Leases	0.3
Financing Cash Flows from Finance Leases	0.4
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	1.3
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 1.3
CL&P
Weighted-Average Remaining Lease Term:
Operating Leases	3 years
Financing Leases	3 years
Weighted-Average Discount Rate:
Operating Leases	3.20%
Financing Leases	10.50%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0.1
Operating Cash Flows from Finance Leases	0.2
Financing Cash Flows from Finance Leases	0.3
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0
NSTAR Electric
Weighted-Average Remaining Lease Term:
Operating Leases	21 years
Financing Leases	23 years
Weighted-Average Discount Rate:
Operating Leases	4.10%
Financing Leases	2.90%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0.3
Operating Cash Flows from Finance Leases	0.1
Financing Cash Flows from Finance Leases	0
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0
PSNH
Weighted-Average Remaining Lease Term:
Operating Leases	8 years
Financing Leases	10 years
Weighted-Average Discount Rate:
Operating Leases	3.60%
Financing Leases	3.50%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0
Operating Cash Flows from Finance Leases	0
Financing Cash Flows from Finance Leases	0
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0

LEASES - Future Minimum Lease P

LEASES - Future Minimum Lease Payments under Long-Term Leases (Details) $ in Millions	Mar. 31, 2019USD ($)
Operating Leases
April 1, 2019 through December 31, 2019	$ 8.3
Year Ending December 31,
2020	9.6
2021	8.7
2022	7.3
2023	4.8
2024	2.8
Thereafter	29.7
Future lease payments	71.2
Less amount representing interest	14.5
Present value of future minimum lease payments	56.7
Finance Leases
April 1, 2019 through December 31, 2019	2.5
Year Ending December 31,
2020	3.4
2021	2.9
2022	1.5
2023	0.7
2024	0.7
Thereafter	13.2
Future lease payments	24.9
Less amount representing interest	13.9
Present value of future minimum lease payments	11
CL&P
Operating Leases
April 1, 2019 through December 31, 2019	0.2
Year Ending December 31,
2020	0.2
2021	0
2022	0
2023	0
2024	0
Thereafter	0.1
Future lease payments	0.5
Less amount representing interest	0
Present value of future minimum lease payments	0.5
Finance Leases
April 1, 2019 through December 31, 2019	1.5
Year Ending December 31,
2020	2
2021	1.5
2022	0
2023	0
2024	0
Thereafter	0
Future lease payments	5
Less amount representing interest	0.8
Present value of future minimum lease payments	4.2
NSTAR Electric
Operating Leases
April 1, 2019 through December 31, 2019	1.4
Year Ending December 31,
2020	1.6
2021	1.6
2022	1.6
2023	1.6
2024	1.7
Thereafter	29.4
Future lease payments	38.9
Less amount representing interest	13.8
Present value of future minimum lease payments	25.1
Finance Leases
April 1, 2019 through December 31, 2019	0.4
Year Ending December 31,
2020	0.5
2021	0.5
2022	0.6
2023	0.6
2024	0.6
Thereafter	12.8
Future lease payments	16
Less amount representing interest	11.5
Present value of future minimum lease payments	4.5
PSNH
Operating Leases
April 1, 2019 through December 31, 2019	0.1
Year Ending December 31,
2020	0.1
2021	0.1
2022	0.1
2023	0.1
2024	0.1
Thereafter	0.1
Future lease payments	0.7
Less amount representing interest	0.2
Present value of future minimum lease payments	0.5
Finance Leases
April 1, 2019 through December 31, 2019	0.1
Year Ending December 31,
2020	0.1
2021	0.1
2022	0.1
2023	0.1
2024	0.1
Thereafter	0.4
Future lease payments	1
Less amount representing interest	0.1
Present value of future minimum lease payments	$ 0.9

LEASES - Future Minimum Rental

LEASES - Future Minimum Rental Payments under Operating Leases (Details) $ in Millions	Dec. 31, 2018USD ($)
Operating Leased Assets [Line Items]
2019	$ 11.5
2020	9.8
2021	8.7
2022	7.2
2023	4.7
Thereafter	32.7
Future minimum lease payments	74.6
CL&P
Operating Leased Assets [Line Items]
2019	1.5
2020	1.4
2021	1.2
2022	1.1
2023	0.5
Thereafter	0.2
Future minimum lease payments	5.9
NSTAR Electric
Operating Leased Assets [Line Items]
2019	7.2
2020	6
2021	5.3
2022	4.4
2023	3.1
Thereafter	29.5
Future minimum lease payments	55.5
PSNH
Operating Leased Assets [Line Items]
2019	0.5
2020	0.4
2021	0.4
2022	0.4
2023	0.2
Thereafter	0.3
Future minimum lease payments	$ 2.2

LEASES - Future Minimum Renta_2

LEASES - Future Minimum Rental Payments under Capital Leases (Details) $ in Millions	Dec. 31, 2018USD ($)
Capital Leased Assets [Line Items]
2019	$ 3.4
2020	3.4
2021	2.9
2022	1.5
2023	0.7
Thereafter	13.9
Future minimum lease payments	25.8
Less amount representing interest	13.8
Present value of future minimum lease payments	12
CL&P
Capital Leased Assets [Line Items]
2019	2
2020	2
2021	1.5
2022	0
2023	0
Thereafter	0
Future minimum lease payments	5.5
Less amount representing interest	1
Present value of future minimum lease payments	4.5
NSTAR Electric
Capital Leased Assets [Line Items]
2019	0.5
2020	0.5
2021	0.5
2022	0.6
2023	0.6
Thereafter	13.4
Future minimum lease payments	16.1
Less amount representing interest	12.4
Present value of future minimum lease payments	3.7
PSNH
Capital Leased Assets [Line Items]
2019	0.1
2020	0.1
2021	0.1
2022	0.1
2023	0.1
Thereafter	0.5
Future minimum lease payments	1
Less amount representing interest	0.1
Present value of future minimum lease payments	$ 0.9

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	$ 155,570	$ 155,570
Rate Reduction Bonds	561,727	583,331
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	155,600	155,600
Long-Term Debt	13,089,800	13,086,100
Rate Reduction Bonds	604,900	635,700
Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	157,100	156,800
Long-Term Debt	13,519,600	13,154,900
Rate Reduction Bonds	623,300	645,800
CL&P
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	116,200	116,200
CL&P | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	116,200	116,200
Long-Term Debt	3,265,800	3,254,000
Rate Reduction Bonds	0	0
CL&P | Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	114,200	113,800
Long-Term Debt	3,538,000	3,429,200
Rate Reduction Bonds	0	0
NSTAR Electric
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 | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	43,000	43,000
Long-Term Debt	2,945,200	2,944,800
Rate Reduction Bonds	0	0
NSTAR Electric | Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	42,900	43,000
Long-Term Debt	3,107,300	3,024,100
Rate Reduction Bonds	0	0
PSNH
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate Reduction Bonds	561,727	583,331
PSNH | Carrying Amount
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	805,300	805,200
Rate Reduction Bonds	604,900	635,700
PSNH | Fair Value | Level 2
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	831,100	819,500
Rate Reduction Bonds	$ 623,300	$ 645,800

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications	$ 700	$ (400)
Amounts Reclassified from AOCI	1,500	3,700
Other Comprehensive Income, Net of Tax	2,196	3,273
Total
AOCI Attributable to Parent [Roll Forward]
Balance	(60,000)	(66,400)
Other Comprehensive Income, Net of Tax	2,196	3,273
Balance	(57,800)	(63,100)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Balance	(4,400)
OCI Before Reclassifications	0
Amounts Reclassified from AOCI	300
Other Comprehensive Income, Net of Tax	300
Balance	(4,100)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Balance		(6,200)
OCI Before Reclassifications		0
Amounts Reclassified from AOCI		700
Other Comprehensive Income, Net of Tax		700
Balance		(5,500)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Balance	(500)	0
OCI Before Reclassifications	700	(400)
Amounts Reclassified from AOCI	0	0
Other Comprehensive Income, Net of Tax	700	(400)
Balance	200	(400)
Defined Benefit Plans
AOCI Attributable to Parent [Roll Forward]
Balance	(55,100)	(60,200)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	1,200	3,000
Other Comprehensive Income, Net of Tax	1,200	3,000
Balance	$ (53,900)	$ (57,200)

COMMON SHARES - Common Shares A

COMMON SHARES - Common Shares Authorized and Issued (Details) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Per value (in dollars per share)	$ 5
Authorized (in shares)	380,000,000	380,000,000
Issued (in shares)	333,878,402	333,878,402
CL&P
Class of Stock [Line Items]
Per value (in dollars per share)	$ 10
Authorized (in shares)	24,500,000	24,500,000
Issued (in shares)	6,035,205	6,035,205
NSTAR Electric
Class of Stock [Line Items]
Per value (in dollars per share)	$ 1
Authorized (in shares)	100,000,000	100,000,000
Issued (in shares)	200	200
PSNH
Class of Stock [Line Items]
Per value (in dollars per share)	$ 1
Authorized (in shares)	100,000,000	100,000,000
Issued (in shares)	301	301

COMMON SHARES - Narrative (Deta

COMMON SHARES - Narrative (Details) - shares	Mar. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Treasury stock (in shares)	16,530,932	16,992,594
Common stock outstanding (in shares)	317,347,470	316,885,808

COMMON SHAREHOLDERS' EQUITY A_2

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Dividends on preferred stock	$ 1,880	$ 1,880
Noncontrolling interest attributed to preferred stock of subsidiaries	155,570		$ 155,570
CL&P
Class of Stock [Line Items]
Dividends on preferred stock	1,390	1,390
Noncontrolling interest attributed to preferred stock of subsidiaries	116,200		116,200
NSTAR Electric
Class of Stock [Line Items]
Dividends on preferred stock	490	$ 490
Noncontrolling interest attributed to preferred stock of subsidiaries	$ 43,000		$ 43,000

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net Income Attributable to Common Shareholders	$ 308,678	$ 269,546
Weighted Average Common Shares Outstanding:
Basic (in shares)	317,624,593	317,397,052
Dilutive Effect (in shares)	691,489	595,947
Diluted (in shares)	318,316,082	317,992,999
Basic and Diluted EPS (in dollars per share)	$ 0.97	$ 0.85

REVENUES (Details)

REVENUES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	$ 2,397,300	$ 2,277,100
Operating Revenues	2,415,792	2,287,962
Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,319,200	1,269,700
Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	809,600	759,900
Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	111,400	109,500
Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,240,200	2,139,100
Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	67,600	65,000
Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	74,200	77,100
Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	17,600	21,900
Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(2,300)	(26,000)
Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	14,700	6,600
Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	3,800	4,300
Lease revenue	1,000
Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers
Operating Revenues
Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers
Other
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	258,100	230,900
Operating Revenues	258,100	230,900
Other | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Other | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Other | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Other | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Other | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	13,500	10,100
Other | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Other | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	244,600	220,800
Other | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Other | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	0	0
Other | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	0	0
Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(520,000)	(482,600)
Operating Revenues	(531,100)	(472,000)
Eliminations | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Eliminations | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(1,100)	0
Eliminations | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(2,700)	(2,500)
Eliminations | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(3,800)	(2,500)
Eliminations | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(270,800)	(258,700)
Eliminations | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Eliminations | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(245,400)	(221,400)
Eliminations | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Eliminations | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	(11,100)	10,600
Eliminations | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	0	0
Electric Distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,829,000	1,742,500
Operating Revenues	1,833,900	1,754,600
Electric Distribution | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,033,300	994,400
Electric Distribution | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	652,600	611,400
Electric Distribution | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	82,100	81,500
Electric Distribution | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,768,000	1,687,300
Electric Distribution | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Distribution | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	51,500	58,500
Electric Distribution | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	12,600	16,000
Electric Distribution | Operating Segments | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(3,100)	(19,300)
Electric Distribution | Operating Segments | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	2,100	8,700
Electric Distribution | Operating Segments | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	2,800	3,400
Natural Gas Distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	457,800	425,800
Operating Revenues	468,900	424,900
Natural Gas Distribution | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	258,900	248,900
Natural Gas Distribution | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	143,800	134,700
Natural Gas Distribution | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	30,900	29,500
Natural Gas Distribution | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	433,600	413,100
Natural Gas Distribution | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Natural Gas Distribution | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	21,700	17,800
Natural Gas Distribution | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	900	(600)
Natural Gas Distribution | Operating Segments | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,600	(4,500)
Natural Gas Distribution | Operating Segments | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	10,400	(1,700)
Natural Gas Distribution | Operating Segments | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	700	800
Electric Transmission | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	328,100	316,700
Operating Revenues	340,500	305,000
Electric Transmission | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Transmission | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Transmission | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Transmission | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Transmission | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	324,900	313,600
Electric Transmission | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Transmission | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,200	3,100
Electric Transmission | Operating Segments | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Transmission | Operating Segments | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	12,400	(11,700)
Electric Transmission | Operating Segments | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	0	0
Water Distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	44,300	43,800
Operating Revenues	45,500	44,600
Water Distribution | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	27,000	26,400
Water Distribution | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	14,300	13,800
Water Distribution | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,100	1,000
Water Distribution | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	42,400	41,200
Water Distribution | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Water Distribution | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,000	800
Water Distribution | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,700	4,000
Water Distribution | Operating Segments | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(800)	(2,200)
Water Distribution | Operating Segments | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	900	700
Water Distribution | Operating Segments | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	300	100
CL&P
Disaggregation of Revenue [Line Items]
Operating Revenues	849,246	784,983
CL&P | Other Revenues
Disaggregation of Revenue [Line Items]
Lease revenue	200
CL&P | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	959,200	897,800
CL&P | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	510,500	483,400
CL&P | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	236,700	222,500
CL&P | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	34,600	35,800
CL&P | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	781,800	741,700
CL&P | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	154,800	150,800
CL&P | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	13,700	10,300
CL&P | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	8,900	7,500
CL&P | Operating Segments | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	(12,500)
CL&P | Segment Reconciling Items | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	5,700	(5,100)
CL&P | Segment Reconciling Items | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	1,000	1,300
CL&P | Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	(116,700)	(109,000)
NSTAR Electric
Disaggregation of Revenue [Line Items]
Operating Revenues	797,612	770,127
NSTAR Electric | Other Revenues
Disaggregation of Revenue [Line Items]
Lease revenue	600
NSTAR Electric | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	887,300	854,800
NSTAR Electric | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	371,000	364,200
NSTAR Electric | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	336,500	314,400
NSTAR Electric | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	28,800	28,100
NSTAR Electric | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	736,300	706,700
NSTAR Electric | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	122,600	118,600
NSTAR Electric | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	24,400	24,900
NSTAR Electric | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	4,000	8,300
NSTAR Electric | Operating Segments | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	(3,700)
NSTAR Electric | Segment Reconciling Items | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	7,300	6,700
NSTAR Electric | Segment Reconciling Items | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	1,500	1,700
NSTAR Electric | Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	(98,500)	(93,100)
PSNH
Disaggregation of Revenue [Line Items]
Operating Revenues	276,435	267,350
PSNH | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	311,700	308,000
PSNH | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	151,800	146,800
PSNH | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	79,800	74,900
PSNH | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	18,700	17,600
PSNH | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	250,300	239,300
PSNH | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	47,500	44,200
PSNH | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	13,400	24,100
PSNH | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,600	3,500
PSNH | Operating Segments | Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(3,100)	(3,100)
PSNH | Segment Reconciling Items | Alternative Revenue
Disaggregation of Revenue [Line Items]
Operating Revenues	1,500	(4,600)
PSNH | Segment Reconciling Items | Other Revenues
Disaggregation of Revenue [Line Items]
Operating Revenues	300	400
PSNH | Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	$ (37,100)	$ (36,400)

SEGMENT INFORMATION - Narrative

SEGMENT INFORMATION - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)segmentcompany
Segment Reporting Information [Line Items]
Number of companies that transmit hydro electricity imported from The Hydro-Quebec System in Canada | company	2
CL&P
Segment Reporting Information [Line Items]
Number of reportable segments	1
NSTAR Electric
Segment Reporting Information [Line Items]
Number of reportable segments	1
PSNH
Segment Reporting Information [Line Items]
Number of reportable segments	1
Affiliated Entity
Segment Reporting Information [Line Items]
Affiliate transaction costs classified as Purchased Power, Fuel and Transmission Costs | $	$ 62.5

SEGMENT INFORMATION - Summary o

SEGMENT INFORMATION - Summary of Segment Information and Segmented Total Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating Revenues	$ 2,415,792	$ 2,287,962
Depreciation and Amortization	(285,900)	(249,500)
Other Operating Expenses	(1,635,200)	(1,596,000)
Operating Income	494,700	442,532
Interest Expense	(131,734)	(121,129)
Other Income/(Loss), Net	30,985	33,789
Net Income Attributable to Common Shareholders	308,678	269,546
Cash Flows Used for Investments in Plant	674,694	607,334
Assets	38,941,007		$ 38,241,256
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues
Other
Segment Reporting Information [Line Items]
Operating Revenues	258,100	230,900
Depreciation and Amortization	(13,600)	(12,000)
Other Operating Expenses	(225,500)	(204,700)
Operating Income	19,000	14,200
Interest Expense	(44,200)	(31,900)
Other Income/(Loss), Net	431,700	360,100
Net Income Attributable to Common Shareholders	407,500	346,000
Cash Flows Used for Investments in Plant	55,900	42,700
Assets	18,939,800		17,874,200
Eliminations
Segment Reporting Information [Line Items]
Operating Revenues	(531,100)	(472,000)
Depreciation and Amortization	600	600
Other Operating Expenses	531,000	471,900
Operating Income	500	500
Interest Expense	12,600	7,400
Other Income/(Loss), Net	(427,600)	(355,300)
Net Income Attributable to Common Shareholders	(414,500)	(347,400)
Cash Flows Used for Investments in Plant	0	0
Assets	(18,326,600)		(17,464,900)
Electric Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	1,833,900	1,754,600
Depreciation and Amortization	(179,200)	(144,400)
Other Operating Expenses	(1,475,600)	(1,443,500)
Operating Income	179,100	166,700
Interest Expense	(49,200)	(47,400)
Other Income/(Loss), Net	18,200	19,600
Net Income Attributable to Common Shareholders	120,100	104,200
Cash Flows Used for Investments in Plant	279,300	236,000
Assets	21,507,000		21,389,100
Natural Gas Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	468,900	424,900
Depreciation and Amortization	(20,400)	(26,400)
Other Operating Expenses	(341,300)	(312,600)
Operating Income	107,200	85,900
Interest Expense	(11,700)	(11,100)
Other Income/(Loss), Net	200	2,000
Net Income Attributable to Common Shareholders	76,500	57,800
Cash Flows Used for Investments in Plant	87,400	70,400
Assets	4,019,100		3,904,900
Electric Transmission | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	340,500	305,000
Depreciation and Amortization	(61,500)	(56,600)
Other Operating Expenses	(98,800)	(83,200)
Operating Income	180,200	165,200
Interest Expense	(30,600)	(29,700)
Other Income/(Loss), Net	8,100	8,000
Net Income Attributable to Common Shareholders	118,200	107,400
Cash Flows Used for Investments in Plant	231,400	239,200
Assets	10,533,400		10,285,000
Water Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	45,500	44,600
Depreciation and Amortization	(11,800)	(10,700)
Other Operating Expenses	(25,000)	(23,900)
Operating Income	8,700	10,000
Interest Expense	(8,600)	(8,400)
Other Income/(Loss), Net	400	(600)
Net Income Attributable to Common Shareholders	900	1,500
Cash Flows Used for Investments in Plant	20,700	$ 19,000
Assets	$ 2,268,300		$ 2,253,000