NSTAR Electric (NSARO) 10-Q 8 May 20 2020 Q1 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Document And Entity [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity Registrant Name	EVERSOURCE ENERGY
Entity Incorporation, State or Country Code	MA
Entity Address, Address Line One	300 Cadwell Drive
Entity Address, City or Town	Springfield
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01104
City Area Code	800
Local Phone Number	286-5000
Entity File Number	1-5324
Entity Tax Identification Number	04-2147929
Title of 12(b) Security	Common Shares, $5.00 par value per share
Trading Symbol	ES
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		336,442,541
Entity Central Index Key	0000072741
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false
The Connecticut Light and Power Company
Document And Entity [Line Items]
Entity Registrant Name	THE CONNECTICUT LIGHT AND POWER COMPANY
Entity Incorporation, State or Country Code	CT
Entity Address, Address Line One	107 Selden Street
Entity Address, City or Town	Berlin
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06037-1616
City Area Code	800
Local Phone Number	286-5000
Entity File Number	0-00404
Entity Tax Identification Number	06-0303850
Entity Filer Category	Non-accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		6,035,205
Entity Central Index Key	0000023426
Current Fiscal Year End Date	--12-31
NSTAR Electric Company
Document And Entity [Line Items]
Entity Registrant Name	NSTAR ELECTRIC COMPANY
Entity Incorporation, State or Country Code	MA
Entity Address, Address Line One	800 Boylston Street
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02199
City Area Code	800
Local Phone Number	286-5000
Entity File Number	1-02301
Entity Tax Identification Number	04-1278810
Entity Filer Category	Non-accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		200
Entity Central Index Key	0000013372
Current Fiscal Year End Date	--12-31
Public Service Company of New Hampshire
Document And Entity [Line Items]
Entity Registrant Name	PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE
Entity Incorporation, State or Country Code	NH
Entity Address, Address Line One	Energy Park
Entity Address, Address Line Two	780 North Commercial Street
Entity Address, City or Town	Manchester
Entity Address, State or Province	NH
Entity Address, Postal Zip Code	03101-1134
City Area Code	800
Local Phone Number	286-5000
Entity File Number	1-6392
Entity Tax Identification Number	02-0181050
Entity Filer Category	Non-accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		301
Entity Central Index Key	0000315256
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current Assets:
Cash	$ 47,425	$ 15,432
Receivables, Net (net of allowance for uncollectible accounts)	1,018,941	989,383
Unbilled Revenues	155,224	181,006
Fuel, Materials, Supplies and REC Inventory	286,498	235,471
Regulatory Assets	785,125	651,112
Prepayments and Other Current Assets	269,457	342,135
Total Current Assets	2,562,670	2,414,539
Property, Plant and Equipment, Net	28,041,356	27,585,470
Deferred Debits and Other Assets:
Regulatory Assets	4,778,321	4,863,639
Goodwill	4,427,266	4,427,266
Investments in Unconsolidated Affiliates	876,328	871,633
Marketable Securities	418,715	449,130
Other Long-Term Assets	544,330	512,238
Total Deferred Debits and Other Assets	11,044,960	11,123,906
Total Assets	41,648,986	41,123,915
Current Liabilities:
Notes Payable	661,420	889,084
Long-Term Debt – Current Portion	532,440	327,411
Rate Reduction Bonds – Current Portion	43,210	43,210
Accounts Payable	914,333	1,147,872
Renewable Portfolio Standards Compliance Obligations	192,660	160,149
Regulatory Liabilities	439,859	361,152
Other Current Liabilities	611,706	676,685
Total Current Liabilities	3,395,628	3,605,563
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	3,816,988	3,755,777
Regulatory Liabilities	3,668,158	3,658,042
Derivative Liabilities	342,990	338,710
Asset Retirement Obligations	489,519	488,511
Accrued Pension, SERP and PBOP	1,331,884	1,370,245
Other Long-Term Liabilities	821,195	810,553
Total Deferred Credits and Other Liabilities	10,470,734	10,421,838
Long-Term Debt	13,898,581	13,770,828
Rate Reduction Bonds	518,517	540,122
Noncontrolling Interest – Preferred Stock of Subsidiaries	155,570	155,570
Common Shareholders' Equity:
Common Shares	1,759,092	1,729,292
Capital Surplus, Paid In	7,479,689	7,087,768
Retained Earnings	4,322,825	4,177,048
Accumulated Other Comprehensive Income (Loss)	(63,111)	(65,059)
Treasury Stock	(288,539)	(299,055)
Common Shareholders' Equity	13,209,956	12,629,994
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	41,648,986	41,123,915
The Connecticut Light and Power Company
Current Assets:
Cash	3,785	0
Receivables, Net (net of allowance for uncollectible accounts)	389,102	400,927
Accounts Receivable from Affiliated Companies	33,701	24,577
Unbilled Revenues	49,982	56,465
Fuel, Materials, Supplies and REC Inventory	49,962	50,700
Regulatory Assets	290,630	178,607
Prepayments and Other Current Assets	69,767	73,184
Total Current Assets	886,929	784,460
Property, Plant and Equipment, Net	9,760,890	9,625,765
Deferred Debits and Other Assets:
Regulatory Assets	1,529,003	1,557,261
Other Long-Term Assets	250,243	217,705
Total Deferred Debits and Other Assets	1,779,246	1,774,966
Total Assets	12,427,065	12,185,191
Current Liabilities:
Notes Payable to Eversource Parent	219,000	63,800
Accounts Payable	331,491	374,698
Accounts Payable to Affiliated Companies	88,553	97,793
Obligations to Third Party Suppliers	50,335	56,952
Regulatory Liabilities	119,283	82,763
Derivative Liabilities	69,631	67,804
Other Current Liabilities	152,138	132,339
Total Current Liabilities	1,030,431	876,149
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,270,025	1,244,551
Regulatory Liabilities	1,179,663	1,164,991
Derivative Liabilities	342,701	338,594
Accrued Pension, SERP and PBOP	385,451	391,159
Other Long-Term Liabilities	149,693	147,586
Total Deferred Credits and Other Liabilities	3,327,533	3,286,881
Long-Term Debt	3,518,129	3,518,136
Noncontrolling Interest – Preferred Stock of Subsidiaries	116,200	116,200
Common Shareholders' Equity:
Common Shares	60,352	60,352
Capital Surplus, Paid In	2,535,765	2,535,765
Retained Earnings	1,838,340	1,791,392
Accumulated Other Comprehensive Income (Loss)	315	316
Common Shareholders' Equity	4,434,772	4,387,825
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	12,427,065	12,185,191
NSTAR Electric Company
Current Assets:
Cash	2,844	52
Receivables, Net (net of allowance for uncollectible accounts)	375,587	346,785
Accounts Receivable from Affiliated Companies	66,838	29,914
Unbilled Revenues	32,629	37,482
Fuel, Materials, Supplies and REC Inventory	178,510	124,060
Regulatory Assets	304,007	285,591
Prepayments and Other Current Assets	16,305	31,150
Total Current Assets	976,720	855,034
Property, Plant and Equipment, Net	9,614,555	9,472,770
Deferred Debits and Other Assets:
Regulatory Assets	1,225,314	1,250,029
Prepaid PBOP	172,244	166,058
Other Long-Term Assets	139,304	144,368
Total Deferred Debits and Other Assets	1,536,862	1,560,455
Total Assets	12,128,137	11,888,259
Current Liabilities:
Notes Payable	88,000	10,500
Notes Payable to Eversource Parent	38,400	30,300
Long-Term Debt – Current Portion	0	95,000
Accounts Payable	264,148	363,691
Accounts Payable to Affiliated Companies	93,344	96,307
Obligations to Third Party Suppliers	107,341	108,827
Renewable Portfolio Standards Compliance Obligations	179,075	150,429
Regulatory Liabilities	219,872	209,180
Other Current Liabilities	68,463	71,333
Total Current Liabilities	1,058,643	1,135,567
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,374,963	1,357,265
Regulatory Liabilities	1,515,732	1,516,585
Accrued Pension, SERP and PBOP	95,746	108,243
Other Long-Term Liabilities	334,538	320,629
Total Deferred Credits and Other Liabilities	3,320,979	3,302,722
Long-Term Debt	3,642,325	3,247,086
Noncontrolling Interest – Preferred Stock of Subsidiaries	43,000	43,000
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	1,813,442	1,813,442
Retained Earnings	2,249,526	2,346,287
Accumulated Other Comprehensive Income (Loss)	222	155
Common Shareholders' Equity	4,063,190	4,159,884
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	12,128,137	11,888,259
Public Service Company of New Hampshire
Current Assets:
Cash	19	413
Receivables, Net (net of allowance for uncollectible accounts)	99,792	99,934
Accounts Receivable from Affiliated Companies	10,176	6,763
Unbilled Revenues	42,344	48,146
Fuel, Materials, Supplies and REC Inventory	28,483	24,957
Regulatory Assets	102,438	84,053
Special Deposits	16,627	32,513
Prepayments and Other Current Assets	6,268	19,431
Total Current Assets	306,147	316,210
Property, Plant and Equipment, Net	3,187,282	3,129,506
Deferred Debits and Other Assets:
Regulatory Assets	843,904	861,672
Other Long-Term Assets	41,564	43,270
Total Deferred Debits and Other Assets	885,468	904,942
Total Assets	4,378,897	4,350,658
Current Liabilities:
Notes Payable to Eversource Parent	84,700	27,000
Rate Reduction Bonds – Current Portion	43,210	43,210
Accounts Payable	103,551	127,081
Accounts Payable to Affiliated Companies	32,707	37,946
Regulatory Liabilities	69,042	65,766
Accrued Interest	14,323	19,138
Other Current Liabilities	39,636	32,736
Total Current Liabilities	387,169	352,877
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	511,822	506,212
Regulatory Liabilities	411,959	413,381
Accrued Pension, SERP and PBOP	152,649	157,638
Other Long-Term Liabilities	36,022	37,075
Total Deferred Credits and Other Liabilities	1,112,452	1,114,306
Long-Term Debt	951,747	951,620
Rate Reduction Bonds	518,517	540,122
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	903,134	903,134
Retained Earnings	507,307	490,306
Accumulated Other Comprehensive Income (Loss)	(1,429)	(1,707)
Common Shareholders' Equity	1,409,012	1,391,733
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	$ 4,378,897	$ 4,350,658

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Provision for uncollectible accounts	$ 262,078	$ 224,821
The Connecticut Light and Power Company
Provision for uncollectible accounts	130,876	97,348
NSTAR Electric Company
Provision for uncollectible accounts	71,111	75,406
Public Service Company of New Hampshire
Provision for uncollectible accounts	$ 11,154	$ 10,497

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Revenues	$ 2,373,726	$ 2,415,792
Operating Expenses:
Purchased Power, Fuel and Transmission	876,570	974,882
Operations and Maintenance	342,062	335,597
Depreciation	236,211	214,948
Amortization	49,776	70,961
Energy Efficiency Programs	148,393	140,116
Taxes Other Than Income Taxes	181,594	184,588
Total Operating Expenses	1,834,606	1,921,092
Operating Income/(Loss)	539,120	494,700
Interest Expense	134,715	131,734
Other Income, Net	24,104	30,985
Income Before Income Tax Expense	428,509	393,951
Income Tax Expense	91,876	83,393
Net Income	336,633	310,558
Net Income Attributable to Noncontrolling Interests	1,880	1,880
Net Income Attributable to Common Shareholders	$ 334,753	$ 308,678
Basic Earnings Per Common Share (in dollars per share)	$ 1.01	$ 0.97
Weighted Average Common Shares Outstanding:
Basic (in shares)	331,102,237	317,624,593
Diluted (in shares)	332,937,153	318,316,082
The Connecticut Light and Power Company
Operating Revenues	$ 899,703	$ 849,246
Operating Expenses:
Purchased Power, Fuel and Transmission	374,717	319,833
Operations and Maintenance	135,597	130,637
Depreciation	78,435	73,289
Amortization of Regulatory Assets, Net	6,548	35,671
Energy Efficiency Programs	35,479	25,988
Taxes Other Than Income Taxes	82,987	92,000
Total Operating Expenses	713,763	677,418
Operating Income/(Loss)	185,940	171,828
Interest Expense	37,883	35,781
Other Income, Net	1,898	3,880
Income Before Income Tax Expense	149,955	139,927
Income Tax Expense	31,217	29,456
Net Income	118,738	110,471
NSTAR Electric Company
Operating Revenues	733,833	797,612
Operating Expenses:
Purchased Power, Fuel and Transmission	242,439	330,104
Operations and Maintenance	122,318	112,963
Depreciation	78,345	72,584
Amortization of Regulatory Assets, Net	27,008	22,584
Energy Efficiency Programs	68,667	76,729
Taxes Other Than Income Taxes	48,722	44,822
Total Operating Expenses	587,499	659,786
Operating Income/(Loss)	146,334	137,826
Interest Expense	31,017	27,881
Other Income, Net	12,238	11,086
Income Before Income Tax Expense	127,555	121,031
Income Tax Expense	27,165	27,017
Net Income	100,390	94,014
Public Service Company of New Hampshire
Operating Revenues	276,368	276,435
Operating Expenses:
Purchased Power, Fuel and Transmission	94,138	113,531
Operations and Maintenance	47,128	52,630
Depreciation	24,334	22,919
Amortization of Regulatory Assets, Net	20,110	13,667
Energy Efficiency Programs	9,364	6,714
Taxes Other Than Income Taxes	19,701	17,311
Total Operating Expenses	214,775	226,772
Operating Income/(Loss)	61,593	49,663
Interest Expense	14,479	14,367
Other Income, Net	3,190	7,022
Income Before Income Tax Expense	50,304	42,318
Income Tax Expense	10,703	9,537
Net Income	$ 39,601	$ 32,781

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Income	$ 336,633	$ 310,558
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	229	316
Changes in Unrealized Gains on Marketable Securities	160	655
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	1,559	1,225
Other Comprehensive Income (Loss), Net of Tax	1,948	2,196
Comprehensive Income Attributable to Noncontrolling Interests	(1,880)	(1,880)
Comprehensive Income Attributable to Common Shareholders	336,701	310,874
The Connecticut Light and Power Company
Net Income	118,738	110,471
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	(7)	(6)
Changes in Unrealized Gains on Marketable Securities	6	23
Other Comprehensive Income (Loss), Net of Tax	(1)	17
Comprehensive Income Attributable to Common Shareholders	118,737	110,488
NSTAR Electric Company
Net Income	100,390	94,014
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	109	110
Changes in Unrealized Gains on Marketable Securities	1	6
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	(43)	1
Other Comprehensive Income (Loss), Net of Tax	67	117
Comprehensive Income Attributable to Common Shareholders	100,457	94,131
Public Service Company of New Hampshire
Net Income	39,601	32,781
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	269	269
Changes in Unrealized Gains on Marketable Securities	9	38
Other Comprehensive Income (Loss), Net of Tax	278	307
Comprehensive Income Attributable to Common Shareholders	$ 39,879	$ 33,088

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 Income (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 Income (Loss)	NSTAR Electric Company	NSTAR Electric CompanyCommon Shares	NSTAR Electric CompanyCapital Surplus, Paid In	NSTAR Electric CompanyRetained Earnings	NSTAR Electric CompanyAccumulated Other Comprehensive Income (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 Income (Loss)
Balance (in shares) at Dec. 31, 2018		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 (Loss)	2,196				2,196		17				17	117				117	307				307
Balance (in shares) at Mar. 31, 2019		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)
Balance (in shares) at Dec. 31, 2019	329,880,645	329,880,645						6,035,205					200					301
Balance at Dec. 31, 2019	$ 12,629,994	$ 1,729,292	7,087,768	4,177,048	(65,059)	(299,055)	4,387,825	$ 60,352	2,535,765	1,791,392	316	4,159,884	$ 0	1,813,442	2,346,287	155	1,391,733	$ 0	903,134	490,306	(1,707)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	336,633			336,633			118,738			118,738		100,390			100,390		39,601			39,601
Dividends on Common Shares	(187,462)			(187,462)			(69,500)			(69,500)		(196,500)			(196,500)		(22,300)			(22,300)
Dividends on Preferred Stock	$ (1,880)			(1,880)			(1,390)			(1,390)		(490)			(490)
Issuance of Common Shares (in shares)	5,960,000	5,960,000
Issuance of Common Shares	$ 432,100	$ 29,800	402,300
Long-Term Incentive Plan Activity	(15,295)		(15,295)
Issuance of Treasury Shares (in shares)		570,542
Issuance of Treasury Shares	27,746		17,230			10,516
Capital Stock Expense	(12,314)		(12,314)
Other Comprehensive Income (Loss)	$ 1,948				1,948		(1)				(1)	67				67	278				278
Balance (in shares) at Mar. 31, 2020	336,411,187	336,411,187						6,035,205					200					301
Balance at Mar. 31, 2020	$ 13,209,956	$ 1,759,092	$ 7,479,689	$ 4,322,825	$ (63,111)	$ (288,539)	$ 4,434,772	$ 60,352	$ 2,535,765	$ 1,838,340	$ 315	$ 4,063,190	$ 0	$ 1,813,442	$ 2,249,526	$ 222	$ 1,409,012	$ 0	$ 903,134	$ 507,307	$ (1,429)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Dividends on Common Shares (in dollars per share)	$ 0.5675	$ 0.535
Issuance of Common Shares, par value (in dollars per share)	$ 5

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Activities:
Net Income	$ 336,633	$ 310,558
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	236,211	214,948
Deferred Income Taxes	44,201	18,085
Uncollectible Expense	11,353	18,565
Pension, SERP and PBOP Expense, Net	1,953	8,428
Pension and PBOP Contributions	(723)	(4,700)
Regulatory (Under)/Over Recoveries, Net	(22,288)	(19,232)
Amortization	49,776	70,961
Other	(33,317)	(37,310)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(55,290)	(155,823)
Fuel, Materials, Supplies and REC Inventory	(51,027)	(39,063)
Taxes Receivable/Accrued, Net	92,140	126,381
Accounts Payable	(127,366)	(60,121)
Other Current Assets and Liabilities, Net	(61,950)	(70,242)
Net Cash Flows Provided by Operating Activities	420,306	381,435
Investing Activities:
Investments in Property, Plant and Equipment	(725,520)	(628,129)
Proceeds from Sales of Marketable Securities	58,627	234,497
Purchases of Marketable Securities	(50,723)	(237,794)
Investments in Unconsolidated Affiliates, Net	(6,113)	(249,138)
Other Investing Activities	6,119	4,893
Net Cash Flows Used in Investing Activities	(717,610)	(875,671)
Financing Activities:
Issuance of Common Shares, Net of Issuance Costs	419,786	0
Cash Dividends on Common Shares	(181,608)	(169,757)
Cash Dividends on Preferred Stock	(1,880)	(1,880)
(Decrease)/Increase in Notes Payable	(408,950)	829,430
Repayment of Rate Reduction Bonds	(21,605)	(30,727)
Issuance of Long-Term Debt	750,000	0
Retirement of Long-Term Debt	(220,253)	(250,215)
Other Financing Activities	(21,560)	16,433
Net Cash Flows Provided by/(Used in) Financing Activities	313,930	393,284
Net Increase/(Decrease) in Cash and Restricted Cash	16,626	(100,952)
Cash and Restricted Cash - Beginning of Period	117,063	209,324
Cash and Restricted Cash - End of Period	133,689	108,372
The Connecticut Light and Power Company
Operating Activities:
Net Income	118,738	110,471
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	78,435	73,289
Deferred Income Taxes	19,910	15,188
Uncollectible Expense	3,230	4,116
Pension, SERP and PBOP Expense, Net	3,315	4,063
Regulatory (Under)/Over Recoveries, Net	(34,198)	(54,671)
Amortization of Regulatory Assets, Net	6,548	35,671
Other	(27,239)	(5,848)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(27,969)	(60,506)
Taxes Receivable/Accrued, Net	40,505	41,399
Accounts Payable	(27,298)	75,373
Other Current Assets and Liabilities, Net	(21,801)	(40,274)
Net Cash Flows Provided by Operating Activities	132,176	198,271
Investing Activities:
Investments in Property, Plant and Equipment	(212,374)	(189,423)
Other Investing Activities	74	59
Net Cash Flows Used in Investing Activities	(212,300)	(189,364)
Financing Activities:
Cash Dividends on Common Shares	(69,500)	(99,000)
Cash Dividends on Preferred Stock	(1,390)	(1,390)
Retirement of Long-Term Debt	0	(250,000)
Increase in Notes Payable to Eversource Parent	155,200	261,600
Other Financing Activities	(390)	(326)
Net Cash Flows Provided by/(Used in) Financing Activities	83,920	(89,116)
Net Increase/(Decrease) in Cash and Restricted Cash	3,796	(80,209)
Cash and Restricted Cash - Beginning of Period	4,971	91,613
Cash and Restricted Cash - End of Period	8,767	11,404
NSTAR Electric Company
Operating Activities:
Net Income	100,390	94,014
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	78,345	72,584
Deferred Income Taxes	9,775	3,722
Uncollectible Expense	3,704	5,953
Pension, SERP and PBOP Income, Net	(4,754)	(4,279)
Pension and PBOP Contributions	0	(1,503)
Regulatory (Under)/Over Recoveries, Net	(17,434)	4,329
Amortization of Regulatory Assets, Net	27,008	22,584
Other	(1,643)	(8,043)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(64,951)	(29,220)
Fuel, Materials, Supplies and REC Inventory	(54,450)	(46,020)
Taxes Receivable/Accrued, Net	32,135	29,483
Accounts Payable	(53,462)	(18,109)
Other Current Assets and Liabilities, Net	7,033	11,466
Net Cash Flows Provided by Operating Activities	61,696	136,961
Investing Activities:
Investments in Property, Plant and Equipment	(247,549)	(208,540)
Other Investing Activities	21	17
Net Cash Flows Used in Investing Activities	(247,528)	(208,523)
Financing Activities:
Cash Dividends on Common Shares	(196,500)	(60,600)
Cash Dividends on Preferred Stock	(490)	(490)
Capital Contributions from Eversource Parent	0	20,000
Increase in Notes Payable to Eversource Parent	8,100	22,300
(Decrease)/Increase in Notes Payable	77,500	89,930
Issuance of Long-Term Debt	400,000	0
Retirement of Long-Term Debt	(95,000)	0
Other Financing Activities	(4,961)	668
Net Cash Flows Provided by/(Used in) Financing Activities	188,649	71,808
Net Increase/(Decrease) in Cash and Restricted Cash	2,817	246
Cash and Restricted Cash - Beginning of Period	6,312	14,659
Cash and Restricted Cash - End of Period	9,129	14,905
Public Service Company of New Hampshire
Operating Activities:
Net Income	39,601	32,781
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	24,334	22,919
Deferred Income Taxes	4,167	6,541
Uncollectible Expense	666	1,725
Regulatory (Under)/Over Recoveries, Net	(22,977)	(26,986)
Amortization of Regulatory Assets, Net	20,110	13,667
Other	(3,885)	(1,621)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	2,843	1,103
Fuel, Materials, Supplies and REC Inventory	(3,526)	144
Taxes Receivable/Accrued, Net	6,110	17,572
Accounts Payable	(18,064)	11,762
Other Current Assets and Liabilities, Net	9,118	6,472
Net Cash Flows Provided by Operating Activities	58,497	86,079
Investing Activities:
Investments in Property, Plant and Equipment	(88,694)	(64,361)
Other Investing Activities	126	102
Net Cash Flows Used in Investing Activities	(88,568)	(64,259)
Financing Activities:
Cash Dividends on Common Shares	(22,300)	(19,000)
Repayment of Rate Reduction Bonds	(21,605)	(30,727)
Increase in Notes Payable to Eversource Parent	57,700	4,000
Other Financing Activities	(22)	(20)
Net Cash Flows Provided by/(Used in) Financing Activities	13,773	(45,747)
Net Increase/(Decrease) in Cash and Restricted Cash	(16,298)	(23,927)
Cash and Restricted Cash - Beginning of Period	36,688	52,723
Cash and Restricted Cash - End of Period	$ 20,390	$ 28,796

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2020
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 2019 Form 10-K, which was filed with the SEC on February 27, 2020. 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, 2020 and December 31, 2019 , and the results of operations, comprehensive income, common shareholders' equity, and cash flows for the three months ended March 31, 2020 and 2019 . The results of operations, comprehensive income, and cash flows for the three months ended March 31, 2020 and 2019 are not necessarily indicative of the results expected for a full year. Eversource consolidates the operations of CYAPC and YAEC, both of which are inactive regional nuclear power companies engaged in the long-term storage of their spent nuclear fuel. 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 holds several equity ownership interests that are not consolidated and are accounted for under the equity method. 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. In March 2020, the World Health Organization declared the outbreak of the 2019 novel coronavirus (COVID-19) a pandemic and President Trump declared a national emergency affecting the entire United States where each state qualifies as being part of a national disaster. The spread of COVID-19 has adversely affected workforces, the overall economy and caused significant volatility in the financial markets. To date, Eversource has not experienced significant operational or financial impacts directly related to the pandemic. Due to the inherent uncertainty of the unprecedented and rapidly evolving situation, management will continue to closely monitor how COVID-19 related developments affect Eversource. As of the date of our filing and based on information available, management is unable to predict the impacts that the COVID-19 pandemic will have on future operations, financial position, results of operations, and cash flows. The extent of the impact in the future will vary and depend in large part on the duration, scope and severity of a national and global economic slowdown, risk of inflation, governmental and regulatory actions, the maintenance of a strong regional and national healthcare system, and the continued spread of the virus, which is mitigated through social distancing measures. Our customer receivable balances and uncollectible accounts have not been materially impacted by COVID-19. We believe that we will be able to develop a successful structure with our respective state regulatory commissions to recover our costs associated with COVID-19, while balancing the impact on our customers’ bills. See Note 1C, "Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts," for further discussion of our evaluation of the allowance for doubtful accounts as of March 31, 2020 in light of the COVID-19 pandemic. An extended economic slowdown could result in lower demand for electricity, natural gas and/or water by our commercial and industrial customers. However, fluctuations in retail sales volumes for CL&P, NSTAR Electric, Yankee Gas, NSTAR Gas and our Connecticut water distribution business are not expected to materially impact earnings due to their respective regulatory commission-approved distribution revenue decoupling mechanisms. The revenue decoupling mechanisms mitigate the im pact of lower demand and resulting lost sales revenues by allowing for a true-up to occur as part of each company’s annual decoupling filing. These revenue decoupling mechanisms qualify as alternative revenue programs in accordance with accounting guidance for rate-regulated operations. As of March 31, 2020, we did not have indicators of triggering events for impairments to our goodwill, long-lived assets, available-for-sale debt securities, or equity method investment carrying values. Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation. The Eversource and PSNH 2019 statements of cash flows and the 2019 segment footnote were revised to correct an error in the presentation of non-cash capital additions. The impact of this revision on the statement of cash flows is a decrease to operating cash inflows in Accounts Payable of $46.6 million and a corresponding decrease to investing cash outflows in Investments in Property, Plant and Equipment for the quarter ended March 31, 2019. This revision is not deemed material, individually or in the aggregate, to the previously issued financial statements. B. Accounting Standards Accounting Standards Issued but Not Yet Effective: In December 2019, the FASB issued Accounting Standards Update (ASU) 2019-12, Income Taxes (Topic 740) - Simplifying the Accounting for Income Taxes , which eliminates certain exceptions to the general principles of current income tax guidance in ASC 740 and simplifies and improves consistency in application of that income tax guidance through clarifications of and amendments to ASC 740. The guidance is effective in the first quarter of 2021. The ASU is not expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric and PSNH. Accounting Standards Recently Adopted: On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a model for recognizing credit losses on financial instruments based on an estimate of current expected losses, requiring immediate recognition of credit losses expected over the life of a financial instrument. The Company determined the impacts of this standard on the allowance for credit losses on its financial instruments, primarily accounts receivable. As of January 1, 2020, the Company recorded increases to the allowance for uncollectible accounts for late fees and other receivable amounts of $1.6 million , $0.9 million , $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively. The impact to retained earnings, net of tax, was $1.5 million , $0.9 million , $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively. The Company also adjusted the allowance for uncollectible amounts of hardship receivables and other low-income assistance programs, which are ultimately collectible in rates at specified points in time under approved regulatory mechanisms. The impact on the allowance, which was offset in other long-term assets on the balance sheets, was an increase of $22.2 million and $21.3 million at Eversource and CL&P, respectively, and a decrease of $1.5 million at NSTAR Electric. See Note 1C, “Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts,” for further information. The Company adopted ASU 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment as of January 1, 2020 . The ASU simplified the accounting for goodwill impairment by removing a complex step in the goodwill impairment test. Under the guidance, goodwill impairment is measured as the amount by which its carrying value exceeds its fair value. The ASU is not expected to have an impact on the financial statements of Eversource. On January 1, 2020, the Company adopted ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The ASU aligned the requirements for capitalizing costs incurred to implement a cloud computing arrangement with existing internal-use software guidance. The prospective implementation of this standard did not have any impact on the financial statements of Eversource, CL&P, NSTAR Electric or PSNH for the period ending March 31, 2020 . On January 1, 2020, the Company prospectively adopted ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement . The ASU modified fair value disclosure requirements . The standard includes new disclosure requirements for Level 3 unobservable inputs and eliminated the requirement to disclose certain information relating to transfers between levels. The modified disclosures are included in Note 1D, “Summary of Significant Accounting Policies - Fair Value Measurements,” and Note 4, “Derivative Instruments.” C. Allowance for Uncollectible Accounts Receivables, Net on the balance sheets primarily i ncludes trade receivables from retail customers and customers related to wholesale transmission contracts, wholesale market sales, sales of RECs and property rentals. Receivables, Net also includes customer receivables for the purchase of electricity from a competitive third party supplier, the current portion of customer energy efficiency loans, property damage receivables and other miscellaneous receivables. There is no material concentration of receivables. Receivables are recorded at amortized cost, net of a credit loss provision (or allowance for uncollectible accounts). Receivables are presented net of expected credit losses at estimated net realizable value by maintaining an allowance for uncollectible accounts. Effective January 1, 2020, the current expected credit loss (CECL) model was applied to receivables for purposes of calculating the allowance for uncollectible accounts. This model is based on expected losses and results in the recognition of estimated expected credit losses, including uncollectible amounts for both billed and unbilled revenues, over the life of the receivable at the time a receivable is recorded. The allowance for uncollectible accounts is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. Factors in determining credit loss include historical collection, write-off experience, and management's assessment of collectibility from customers, including current conditions, reasonable forecasts, and expectations of future collectibility and collection efforts. Management continuously assesses the collectibility of receivables and adjusts estimates based on actual experience and future expectations based on economic indicators. Management also monitors the aging analysis of receivables to determine if there are changes in the collections of accounts receivable. Receivable balances are written off against the allowance for uncollectible accounts when the customer accounts are no longer in service and these balances are deemed to be uncollectible. As of March 31, 2020, management evaluated the adequacy of the allowance for uncollectible accounts in light of the COVID-19 pandemic and the economic downturn to date. This evaluation included an analysis of collection and customer payment trends in 2020, economic conditions, flexible payment plans and financial hardship arrearage management programs being offered to customers, and the impacts of federal governmental pandemic relief programs for our customers and the expansion of unemployment benefits initiatives, which help to mitigate the potential for increasing customer account delinquencies. Additionally, management considered past economic declines and corresponding uncollectible reserves as part of the current assessment. Based upon the evaluation performed, management concluded that the reserve balance as of March 31, 2020 adequately reflected the collection risk and net realizable value for Eversource’s receivables. Management will continue to evaluate the adequacy of the uncollectible allowance in future reporting periods based on an ongoing assessment of accounts receivable collections, delinquency statistics, and analysis of aging-based quantitative assessments. 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. Hardship customers are protected from shut-off in certain circumstances, and historical collection experience has reflected a higher default risk as compared to the rest of the receivable population. As a result of the adoption of ASU 2016-13, management aligned the allowance for uncollectible hardship accounts across all regulatory jurisdictions, using a higher credit risk profile for this pool of trade receivables as compared to non-hardship receivables. Implementation impacts of the accounting standard on the allowance for uncollectible hardship accounts are reflected in the rollforward of the uncollectible allowance in the table below. The allowance for uncollectible hardship accounts is included in the total uncollectible allowance balance. The total allowance for uncollectible accounts is included in Receivables, Net on the balance sheets. The activity in the allowance for uncollectible accounts by portfolio segment is as follows: For the Three Months Ended March 31, 2020 Eversource CL&P NSTAR Electric PSNH (Millions of Dollars) Hardship Accounts Retail (Non-Hardship), Wholesale, and Other Receivables Total Allowance Hardship Accounts Retail (Non-Hardship), Wholesale and Other Receivables Total Allowance Hardship Accounts Retail (Non-Hardship), Wholesale, and Other Receivables Total Allowance Total Allowance Beginning Balance $ 143.3 $ 81.5 $ 224.8 $ 80.1 $ 17.2 $ 97.3 $ 43.9 $ 31.5 $ 75.4 $ 10.5 ASU 2016-13 Implementation Impact on January 1, 2020 21.6 2.2 23.8 21.3 0.9 22.2 (1.6 ) 0.3 (1.3 ) 0.3 Uncollectible Expense (1) — 11.4 11.4 — 3.2 3.2 — 3.7 3.7 0.7 Uncollectible Costs Deferred (2) 11.8 8.5 20.3 12.9 1.8 14.7 (3.4 ) 3.4 — 1.3 Write-Offs (4.7 ) (16.8 ) (21.5 ) (3.8 ) (3.5 ) (7.3 ) (0.4 ) (8.0 ) (8.4 ) (1.7 ) Recoveries Collected 0.2 3.1 3.3 0.2 0.6 0.8 — 1.7 1.7 0.1 Ending Balance $ 172.2 $ 89.9 $ 262.1 $ 110.7 $ 20.2 $ 130.9 $ 38.5 $ 32.6 $ 71.1 $ 11.2 (1) Uncollectible expense associated with customer and other accounts receivable is included in Operations and Maintenance expense on the statements of income. For the three months ended March 31, 2019 , uncollectible expense included in Operations and Maintenance Expense was $18.6 million , $4.1 million , $6.0 million and $1.7 million for Eversource, CL&P, NSTAR Electric and PSNH, respectively. (2) The current period provision for expected credit losses for hardship accounts and other customer receivables that are ultimately recovered in rates is deferred as a regulatory cost on the balance sheets. D. Fair Value Measurements Fair value measurement guidance is applied to derivative contracts that are not elected or designated as "normal purchases" or "normal sales" (normal) and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill, long-lived assets 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. 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 10, "Fair Value of Financial Instruments," to the financial statements. E. Other Income, Net The components of Other Income, Net on the statements of income were as follows: For the Three Months Ended March 31, 2020 March 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Pension, SERP and PBOP Non-Service Income/(Expense) Components $ 12.7 $ 1.1 $ 7.9 $ 1.9 $ 7.4 $ (0.6 ) $ 7.0 $ 0.5 AFUDC Equity 10.6 3.9 5.0 1.5 10.9 2.6 4.0 0.2 Equity in Earnings of Unconsolidated Affiliates 4.0 — 0.1 — 5.0 — 0.2 — Investment Income/(Loss) (4.3 ) (3.4 ) (1.3 ) (0.5 ) 1.2 1.7 (0.3 ) 0.4 Interest Income 0.7 0.3 0.1 0.3 6.5 0.4 0.2 5.9 Other 0.4 — 0.4 — — (0.2 ) — — Total Other Income, Net $ 24.1 $ 1.9 $ 12.2 $ 3.2 $ 31.0 $ 3.9 $ 11.1 $ 7.0 F. 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, 2020 March 31, 2019 Eversource $ 43.1 $ 45.0 CL&P 35.5 36.2 Separate from above were amounts recorded as Taxes Other Than Income Taxes at CL&P related to the remittance to the State of Connecticut of energy efficiency funds collected from customers of $10.7 million for the three months ended March 31, 2019. Energy efficiency funds collected from customers after July 1, 2019 are no longer subject to remittance to the State of Connecticut. These amounts were 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. As agents for state and local governments, Eversource's companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income. G. Supplemental Cash Flow Information Non-cash investing activities include plant additions included in Accounts Payable as follows: (Millions of Dollars) As of March 31, 2020 As of March 31, 2019 Eversource $ 273.7 $ 336.3 CL&P 85.0 121.9 NSTAR Electric 70.2 83.2 PSNH 37.9 30.4 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, 2020 As of December 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Cash as reported on the Balance Sheets $ 47.4 $ 3.8 $ 2.8 $ — $ 15.4 $ — $ 0.1 $ 0.4 Restricted cash included in: Special Deposits 39.0 4.7 6.2 16.6 52.5 4.6 6.2 32.5 Marketable Securities 44.1 0.3 0.1 0.6 46.0 0.4 — 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 $ 133.7 $ 8.8 $ 9.1 $ 20.4 $ 117.1 $ 5.0 $ 6.3 $ 36.7 Special Deposits represent cash collections related to the PSNH RRB customer charges that are held in trust, required ISO-NE cash deposits, and CYAPC and YAEC cash balances. Special Deposits are included in Current Assets on the balance sheets. Restricted 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 obligations. H. Pending Acquisition of Assets of Columbia Gas of Massachusetts On February 26, 2020, Eversource and NiSource Inc. entered into an asset purchase agreement (the Agreement) pursuant to which Eversource would acquire certain assets that comprise NiSource’s local natural gas distribution business in Massachusetts, which is doing business as Columbia Gas of Massachusetts (CMA). The purchase price of $1.1 billion includes a target working capital amount that is subject to adjustment to reflect actual working capital as of the closing date. The liabilities to be assumed by Eversource under the Agreement specifically exclude any liabilities (past or future) arising out of, or related to, the fires and explosions that occurred on September 13, 2018 in Lawrence, Andover and North Andover, Massachusetts related to the delivery of natural gas by CMA, including certain subsequent events, all as described and in the DPU's Order on Scope dated December 23, 2019 (D.P.U. 19-141) (the Greater Lawrence Incident or GLI). The liabilities to be assumed also exclude any further emergency events prior to the closing of the acquisition related to the restoration and reconstruction with respect to the GLI, including any losses arising out of, or related to, any litigation, demand, cause of action, claim, suit, investigation, proceeding, indemnification agreements or rights. Eversource is not assuming any of CMA's or NiSource Inc.'s debt. The transaction requires approval from the DPU, the Maine Public Utilities Commission, the FERC, and the Federal Communications Commission, and it is subject to review under the Hart-Scott-Rodino Act, for which the relevant review period has expired . The resulting rate plan also requires DPU approval. Eversource expects to finance the asset acquisition through a combination of debt and equity issuances in a ratio that is consistent with our current consolidated capital structure. The transaction is expected to close by the end of the third quarter of 2020.

REGULATORY ACCOUNTING

REGULATORY ACCOUNTING	3 Months Ended
	Mar. 31, 2020
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, plus a return on investment. The application of accounting guidance for rate-regulated enterprises results in recording regulatory assets and liabilities. Regulatory assets represent the deferral of incurred costs that are probable of future recovery in customer rates. Regulatory assets are amortized as the incurred costs are recovered through customer rates. Regulatory liabilities represent either revenues received from customers to fund expected costs that have not yet been incurred or probable future refunds to customers. 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, 2020 As of December 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Benefit Costs $ 2,334.3 $ 528.3 $ 616.3 $ 213.9 $ 2,382.9 $ 539.0 $ 629.8 $ 218.2 Income Taxes, Net 727.2 458.9 108.5 12.8 725.8 458.8 108.0 12.8 Securitized Stranded Costs 554.5 — — 554.5 565.3 — — 565.3 Storm Restoration Costs, Net 497.6 251.6 183.0 63.0 540.6 274.6 200.6 65.4 Regulatory Tracker Mechanisms 551.5 191.0 227.4 84.6 411.5 78.3 207.1 65.8 Derivative Liabilities 335.2 333.8 — — 334.5 329.2 — — Goodwill-related 327.3 — 281.0 — 331.5 — 284.6 — Asset Retirement Obligations 99.3 31.2 51.5 3.7 97.2 30.8 50.3 3.6 Other Regulatory Assets 136.5 24.8 61.6 13.8 125.4 25.2 55.2 14.7 Total Regulatory Assets 5,563.4 1,819.6 1,529.3 946.3 5,514.7 1,735.9 1,535.6 945.8 Less: Current Portion 785.1 290.6 304.0 102.4 651.1 178.6 285.6 84.1 Total Long-Term Regulatory Assets $ 4,778.3 $ 1,529.0 $ 1,225.3 $ 843.9 $ 4,863.6 $ 1,557.3 $ 1,250.0 $ 861.7 Regulatory Costs in Long-Term Assets: Eversource's regulated companies had $171.3 million (including $82.6 million for CL&P, $50.3 million for NSTAR Electric and $16.9 million for PSNH) and $146.0 million (including $51.8 million for CL&P, $55.7 million for NSTAR Electric and $18.0 million for PSNH) of additional regulatory costs as of March 31, 2020 and December 31, 2019 , 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, 2020 As of December 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH EDIT due to Tax Cuts and Jobs Act $ 2,831.2 $ 1,019.8 $ 1,063.9 $ 391.4 $ 2,844.6 $ 1,022.8 $ 1,071.2 $ 392.8 Cost of Removal 579.3 77.4 337.2 14.8 559.8 64.6 330.6 16.3 Benefit Costs 80.1 — 68.6 — 84.5 — 72.2 — Regulatory Tracker Mechanisms 412.5 121.7 189.8 64.1 325.1 94.8 165.6 57.0 AFUDC - Transmission 74.4 45.7 28.7 — 73.2 46.0 27.2 — Other Regulatory Liabilities 130.6 34.4 47.4 10.7 132.0 19.6 59.0 13.1 Total Regulatory Liabilities 4,108.1 1,299.0 1,735.6 481.0 4,019.2 1,247.8 1,725.8 479.2 Less: Current Portion 439.9 119.3 219.9 69.0 361.2 82.8 209.2 65.8 Total Long-Term Regulatory Liabilities $ 3,668.2 $ 1,179.7 $ 1,515.7 $ 412.0 $ 3,658.0 $ 1,165.0 $ 1,516.6 $ 413.4

PROPERTY, PLANT AND EQUIPMENT A

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 (Millions of Dollars) Distribution - Electric $ 16,117.4 $ 15,880.0 Distribution - Natural Gas 3,984.2 3,931.1 Transmission - Electric 11,059.4 10,958.4 Distribution - Water 1,730.2 1,726.5 Solar 200.5 200.2 Utility 33,091.7 32,696.2 Other (1) 1,073.2 1,025.6 Property, Plant and Equipment, Gross 34,164.9 33,721.8 Less: Accumulated Depreciation Utility (7,572.4 ) (7,483.5 ) Other (408.0 ) (387.4 ) Total Accumulated Depreciation (7,980.4 ) (7,870.9 ) Property, Plant and Equipment, Net 26,184.5 25,850.9 Construction Work in Progress 1,856.9 1,734.6 Total Property, Plant and Equipment, Net $ 28,041.4 $ 27,585.5 As of March 31, 2020 As of December 31, 2019 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Distribution - Electric $ 6,607.8 $ 7,250.8 $ 2,299.1 $ 6,485.5 $ 7,163.7 $ 2,271.1 Transmission - Electric 5,094.1 4,444.7 1,515.8 5,043.0 4,411.9 1,498.7 Solar — 200.5 — — 200.2 — Property, Plant and Equipment, Gross 11,701.9 11,896.0 3,814.9 11,528.5 11,775.8 3,769.8 Less: Accumulated Depreciation (2,413.6 ) (2,925.2 ) (810.1 ) (2,385.7 ) (2,895.3 ) (799.9 ) Property, Plant and Equipment, Net 9,288.3 8,970.8 3,004.8 9,142.8 8,880.5 2,969.9 Construction Work in Progress 472.6 643.8 182.5 483.0 592.3 159.6 Total Property, Plant and Equipment, Net $ 9,760.9 $ 9,614.6 $ 3,187.3 $ 9,625.8 $ 9,472.8 $ 3,129.5 (1) These assets are primarily comprised of computer software, hardware and equipment at Eversource Service and buildings at The Rocky River Realty Company.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 (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 $ 12.8 $ (0.4 ) $ 12.4 $ 12.2 $ (0.4 ) $ 11.8 Long-Term Derivative Assets: CL&P Level 3 68.2 (2.1 ) 66.1 67.5 (2.1 ) 65.4 Current Derivative Liabilities: CL&P Level 3 (69.6 ) — (69.6 ) (67.8 ) — (67.8 ) Other Level 2 (1.4 ) 0.3 (1.1 ) (5.2 ) — (5.2 ) Long-Term Derivative Liabilities: CL&P Level 3 (342.7 ) — (342.7 ) (338.6 ) — (338.6 ) Other Level 2 (0.3 ) — (0.3 ) (0.1 ) — (0.1 ) (1) Amounts represent derivative assets and liabilities that Eversource elected to record net on the balance sheets. These amounts are subject to master netting agreements or similar agreements for which the right of offset exists. For further information on the fair value of derivative contracts, see Note 1D, "Summary of Significant Accounting Policies - Fair Value Measurements," to the financial statements. Derivative Contracts at Fair Value with Offsetting Regulatory Amounts Commodity Supply and Price Risk Management : As required by regulation, CL&P, along with UI, has capacity-related contracts with generation facilities. CL&P has a sharing agreement with UI, with 80 percent of the costs or benefits of each contract borne by or allocated to CL&P and 20 percent borne by or allocated to UI. The combined capacities of these contracts as of both March 31, 2020 and December 31, 2019 , were 676 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, 2020 and December 31, 2019 , Eversource had New York Mercantile Exchange (NYMEX) financial contracts for natural gas futures in order to reduce variability associated with the price of 3.5 million and 9.6 million MMBtu of natural gas, respectively. For the three months ended March 31, 2020 and 2019 , there were losses of $18.0 million and $5.2 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 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 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, 2020 As of December 31, 2019 CL&P Range Weighted Average (1) Period Covered Range Period Covered Capacity Prices $ 4.30 — $5.82 $ 4.81 per kW-Month 2024 - 2026 $ 3.01 — $7.34 per kW-Month 2023 - 2026 Forward Reserve Prices 0.80 — 1.90 1.35 per kW-Month 2020 - 2024 0.80 — 1.90 per kW-Month 2020 - 2024 (1) Unobservable inputs were weighted by the relative future capacity and forward reserve prices and contractual MWs over the periods covered. Exit price premiums of 1.5 percent through 13 percent , or a weighted average of 11.9 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. The risk premium was weighted by the relative fair value of the net derivative instruments. 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) 2020 2019 Derivatives, Net: Fair Value as of Beginning of Period $ (329.2 ) $ (356.5 ) Net Realized/Unrealized Losses Included in Regulatory Assets (16.4 ) (5.3 ) Settlements 11.8 8.7 Fair Value as of End of Period $ (333.8 ) $ (353.1 )

MARKETABLE SECURITIES

MARKETABLE SECURITIES	3 Months Ended
	Mar. 31, 2020
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, 2020 and December 31, 2019 was $34.8 million and $45.7 million , respectively. For the three months ended March 31, 2020 and 2019 , there were unrealized losses of $9.1 million and unrealized gains of $1.0 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 $162.0 million and $182.8 million as of March 31, 2020 and December 31, 2019 , 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, 2020 As of December 31, 2019 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 $ 224.2 $ 10.9 $ (0.6 ) $ 234.5 $ 228.4 $ 5.8 $ (0.1 ) $ 234.1 Eversource's debt securities include CYAPC's and YAEC's marketable securities held in spent nuclear fuel trusts in the amounts of $198.7 million and $198.1 million as of March 31, 2020 and December 31, 2019 , 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, excluding amounts related to credit losses or losses on securities intended to be sold, which are recorded in Other Income, Net. There have been no significant unrealized losses and no credit losses for the three months ended March 31, 2020 and 2019 , and no allowance for credit losses as of March 31, 2020 . Factors considered in determining whether a credit loss exists include adverse conditions specifically affecting the issuer, the payment history, ratings and rating changes of the security, and the severity of the impairment. For asset-backed debt securities, underlying collateral and expected future cash flows are also evaluated. Debt securities included in Eversource's non-qualified benefit trust portfolio are investment-grade bonds with a lower default risk based on their credit quality. As of March 31, 2020 , 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) $ 56.5 $ 56.6 One to five years 40.1 41.7 Six to ten years 38.6 41.4 Greater than ten years 89.0 94.8 Total Debt Securities $ 224.2 $ 234.5 (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, 2020 As of December 31, 2019 Level 1: Mutual Funds and Equities $ 196.8 $ 228.5 Money Market Funds 44.1 46.0 Total Level 1 $ 240.9 $ 274.5 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 100.9 $ 96.8 Corporate Debt Securities 45.9 44.0 Asset-Backed Debt Securities 13.7 12.9 Municipal Bonds 22.2 26.7 Other Fixed Income Securities 7.7 7.7 Total Level 2 $ 190.4 $ 188.1 Total Marketable Securities $ 431.3 $ 462.6 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, 2020
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, Yankee Gas and Aquarion Water Company of Connecticut are also parties to a five -year $1.45 billion revolving credit facility, which terminates on December 6, 2024 . 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 6, 2024 . 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, 2020 December 31, 2019 March 31, 2020 December 31, 2019 March 31, 2020 December 31, 2019 (Millions of Dollars) Eversource Parent Commercial Paper Program $ 738.4 $ 1,224.9 $ 711.6 $ 225.1 3.38 % 1.98 % NSTAR Electric Commercial Paper Program 88.0 10.5 562.0 639.5 1.25 % 1.63 % There were no borrowings outstanding on either the Eversource parent or NSTAR Electric revolving credit facilities as of March 31, 2020 or December 31, 2019 . Amounts outstanding under the commercial paper programs and revolving credit facilities are included in Notes Payable and 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 NSTAR Gas long-term debt issuances in May 2020, $25.0 million of the current portion of long-term debt and $165.0 million of commercial paper borrowings under the Eversource parent commercial paper program were classified as Long-Term Debt as of March 31, 2020. The Company expects the future operating cash flows of Eversource, CL&P, NSTAR Electric and PSNH, along with 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 in meeting their short-term borrowing needs. 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, 2020 , there were intercompany loans from Eversource parent to CL&P of $219.0 million , to PSNH of $84.7 million , and to a subsidiary of NSTAR Electric of $38.4 million . As of December 31, 2019 , there were intercompany loans from Eversource parent to CL&P of $ 63.8 million , to PSNH of $ 27.0 million , and to a subsidiary of NSTAR Electric of $ 30.3 million . Intercompany loans from Eversource parent are included in Notes Payable to Eversource Parent and classified in current liabilities on the respective subsidiary's balance sheets. Long-Term Debt Issuance Authorization: On January 27, 2020, the DPU approved NSTAR Gas' request for authorization to issue up to $270 million in long-term debt through December 31, 2021. Long-Term Debt: The following table summarizes long-term debt issuances and repayments: (Millions of Dollars) Issuance/(Repayment) Issue Date or Repayment Date Maturity Date Use of Proceeds for Issuance/ NSTAR Electric: 3.95% 2020 Debentures $ 400.0 March 2020 April 2030 Refinanced investments in eligible green expenditures, which were previously financed in 2018 and 2019 5.10% Series E Senior Notes (95.0 ) March 2020 March 2020 Paid at maturity Other: Eversource Parent 3.45% Series P Senior Notes 350.0 January 2020 January 2050 Paid short-term borrowings NSTAR Gas 4.46% Series N First Mortgage Bonds (125.0 ) January 2020 January 2020 Paid at maturity Yankee Gas 4.87% Series K First Mortgage Bonds (50.0 ) April 2020 April 2020 Paid at maturity NSTAR Gas 2.33% Series R First Mortgage Bonds 75.0 May 2020 May 2025 Refinanced existing indebtedness, funded capital expenditures and for general corporate purposes NSTAR Gas 3.15% Series S First Mortgage Bonds 115.0 May 2020 May 2050 Refinanced existing indebtedness, funded capital expenditures and for general corporate purposes

RATE REDUCTION BONDS AND VARIAB

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES	3 Months Ended
	Mar. 31, 2020
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 are 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 was formed solely to issue RRBs to finance PSNH's unrecovered remaining costs associated with the divestiture of its 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, 2020 As of December 31, 2019 Restricted Cash - Current Portion (included in Current Assets) $ 16.6 $ 32.5 Restricted Cash - Long-Term Portion (included in Other Long-Term Assets) 3.2 3.2 Securitized Stranded Cost (included in Regulatory Assets) 554.5 565.3 Other Regulatory Liabilities (included in Regulatory Liabilities) 6.0 5.6 Accrued Interest (included in Other Current Liabilities) 3.3 8.6 Rate Reduction Bonds - Current Portion 43.2 43.2 Rate Reduction Bonds - Long-Term Portion 518.5 540.1 (Millions of Dollars) For the Three Months Ended Income Statement: March 31, 2020 March 31, 2019 Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net) $ 10.8 $ 10.6 Interest Expense on RRB Principal (included in Interest Expense) 5.0 5.4

PENSION BENEFITS AND POSTRETIRE

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION	3 Months Ended
	Mar. 31, 2020
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/(income), less the capitalized portion, is included in Operations and Maintenance expense on the statements of income. The remaining components of net periodic benefit expense/(income), less the deferred portion, 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 PBOP For the Three Months Ended March 31, 2020 For the Three Months Ended March 31, 2020 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 19.6 $ 5.7 $ 3.8 $ 2.2 $ 2.6 $ 0.5 $ 0.6 $ 0.2 Interest Cost 44.3 9.5 9.6 4.9 6.1 1.2 1.7 0.6 Expected Return on Plan Assets (100.3 ) (20.0 ) (25.8 ) (11.3 ) (18.1 ) (2.4 ) (8.5 ) (1.4 ) Actuarial Loss 49.3 10.0 13.3 4.1 2.1 0.4 0.7 0.1 Prior Service Cost/(Credit) 0.3 — 0.1 — (5.4 ) 0.2 (4.2 ) 0.1 Total Net Periodic Benefit Expense/(Income) $ 13.2 $ 5.2 $ 1.0 $ (0.1 ) $ (12.7 ) $ (0.1 ) $ (9.7 ) $ (0.4 ) Intercompany Allocations N/A $ 1.9 $ 1.9 $ 0.6 N/A $ (0.4 ) $ (0.4 ) $ (0.2 ) Pension and SERP PBOP For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2019 (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 $ 2.1 $ 0.4 $ 0.4 $ 0.2 Interest Cost 54.2 11.5 11.9 6.2 8.1 1.5 2.3 0.9 Expected Return on Plan Assets (92.3 ) (18.8 ) (24.4 ) (10.3 ) (16.6 ) (2.3 ) (7.5 ) (1.3 ) Actuarial Loss 35.8 8.1 9.4 3.5 2.5 0.4 0.9 0.2 Prior Service Cost/(Credit) 1.1 — 0.1 — (5.8 ) 0.3 (4.2 ) 0.1 Total Net Periodic Benefit Expense/(Income) $ 18.1 $ 5.6 $ 0.9 $ 2.0 $ (9.7 ) $ 0.3 $ (8.1 ) $ 0.1 Intercompany Allocations N/A $ 7.8 $ 3.0 $ 2.4 N/A $ (0.1 ) $ (0.2 ) $ (0.1 )

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 Number of Sites Reserve (in millions) Number of Sites Reserve (in millions) Eversource 55 $ 79.1 57 $ 81.0 CL&P 15 11.8 15 11.4 NSTAR Electric 13 6.2 15 8.0 PSNH 9 7.4 9 7.5 Included in the 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 $67.4 million and $67.9 million as of March 31, 2020 and December 31, 2019 , 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. 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. 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 and affiliates to external parties as of March 31, 2020 : Company Description Maximum Exposure (in millions) Expiration Dates Various Surety Bonds (1) $ 30.0 2020 - 2023 Rocky River Realty Company and Eversource Service Lease Payments for Real Estate 6.1 2024 Bay State Wind LLC Real Estate Purchase 2.5 2020 Sunrise Wind LLC Offshore Wind (2) 2.2 - (1) Surety bond expiration dates reflect termination dates, the majority of which will be renewed or extended. Certain surety bonds contain credit ratings triggers that would require Eversource parent to post collateral in the event that the unsecured debt credit ratings of Eversource parent are downgraded. (2) On October 25, 2019, Eversource parent issued a guaranty on behalf of its 50 percent -owned affiliate, Sunrise Wind LLC, whereby Eversource parent will guaranty Sunrise Wind LLC’s performance of certain obligations, in an amount not to exceed $15.4 million , under the Offshore Wind Renewable Energy Certificate Purchase and Sale Agreement (the Agreement). The Agreement was executed on October 23, 2019, by and between the New York State Energy Research and Development Authority (NYSERDA) and Sunrise Wind LLC. The Company regularly reviews performance risk under this arrangement, and in the event it becomes probable that Eversource parent will be required to perform under the guarantee, the amount of probable payment will be recorded. As of March 31, 2020, the fair value of the guarantee was immaterial. C. 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 power 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 accept delivery of, and 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 previously awarded the Yankee Companies damages for Phases 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 a fourth set of 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. On June 12, 2019, each of the Yankee Companies received the damages proceeds. On June 12, 2019, the court accepted an offer of judgment in the amount of $0.5 million to settle the disputed amount of approximately $1 million in Phase IV contested damages. The Yankee Companies received the $0.5 million payment in July 2019. In September 2019, the Yankee Companies made a required informational filing with FERC as to the use of proceeds, for which approval was received in the fourth quarter of 2019. In December 2019, YAEC and MYAPC returned proceeds of $5.4 million and $21.0 million , respectively, to its member companies, of which the Eversource utilities (CL&P, NSTAR Electric and PSNH) received a total of $2.8 million from YAEC and $5.0 million from MYAPC. The Eversource utilities refund these amounts received to their utility customers. Also, in December 2019, CYAPC paid $29.0 million to the DOE to partially settle its pre-1983 spent nuclear fuel obligation. D. FERC ROE Complaints Four separate complaints were 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, 2020 and December 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, 2020 and December 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. 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 illustrative calculations indicated that for the first complaint period, for the NETOs, which FERC concludes are of average financial risk, the preliminary just and reasonable base ROE is 10.41 percent and the preliminary incentive cap on total ROE is 13.08 percent . If the results of the 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. These preliminary calculations are not binding and do not represent what we believe to be the most likely outcome of a final FERC order. On November 21, 2019, FERC issued an order concerning the transmission ROEs for the Midcontinent ISO transmission owners (MISO). In that order, FERC adopted another new methodology for determining base ROEs for MISO, which differed significantly from the methodology and framework set forth in its October 16, 2018 FERC order on the NETOs’ ROE dockets. On December 23, 2019, the NETOs filed a Supplemental Paper Hearing Brief and a Motion to supplement the record in the NETO ROE dockets to respond to the new methodology proposed in the MISO order, as there is uncertainty to whether it may be applied to the NETOs’ cases. On January 21, 2020, the FERC issued an order granting rehearing for further consideration to give the FERC more time to act on the substantive issues of the MISO ROE proceedings. Further changes to the methodology by FERC are possible as a result of the arguments in both the MISO and NETO proceedings. Given the significant uncertainty relating to the October 2018 FERC order, the November 2019 FERC order to MISO, and the FERC's rehearing of the MISO order, the Company is unable to predict the potential effect of the MISO order on the NETO complaints or the outcome of the four complaints and concluded that there is no reasonable basis for a change to the reserve or recognized ROEs for any of the complaint periods at this time. Further, the Company cannot reasonably estimate a range of gain or loss for any of the four complaint proceedings. 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. A change of 10 basis points to the base ROE used to establish the reserves would impact Eversource's after-tax earnings by an average of approximately $3 million for each of the four 15 -month complaint periods. E. Eversource and NSTAR Electric Boston Harbor Civil Action In 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 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 parties reached a settlement pursuant to which HEEC agreed to install a new 115 kV distribution cable across Boston Harbor to Deer Island,

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2020
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, 2020: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 156.0 $ 116.2 $ 113.8 $ 43.0 $ 42.2 $ — $ — Long-Term Debt 14,431.0 15,177.1 3,518.1 3,949.4 3,642.3 3,901.2 951.7 995.8 Rate Reduction Bonds 561.7 596.0 — — — — 561.7 596.0 As of December 31, 2019: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 162.0 $ 116.2 $ 117.8 $ 43.0 $ 44.2 $ — $ — Long-Term Debt 14,098.2 15,170.2 3,518.1 4,058.0 3,342.1 3,659.9 951.6 1,005.7 Rate Reduction Bonds 583.3 625.9 — — — — 583.3 625.9 Derivative Instruments and Marketable Securities: Derivative instruments and investments in marketable securities are carried at fair value. For further information, see Note 4, "Derivative Instruments," and Note 5, "Marketable Securities," to the financial statements. See Note 1D, "Summary of Significant Accounting Policies - Fair Value Measurements," for the fair value measurement policy and the fair value hierarchy.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)	3 Months Ended
	Mar. 31, 2020
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, 2020 For the Three Months Ended March 31, 2019 Eversource (Millions of Dollars) Qualified Cash Flow Hedging Instruments Unrealized Gains on Marketable Securities Defined Benefit Plans Total Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Balance as of January 1st $ (3.0 ) $ 0.7 $ (62.8 ) $ (65.1 ) $ (4.4 ) $ (0.5 ) $ (55.1 ) $ (60.0 ) OCI Before Reclassifications — 0.2 — 0.2 — 0.7 — 0.7 Amounts Reclassified from AOCI 0.2 — 1.6 1.8 0.3 — 1.2 1.5 Net OCI 0.2 0.2 1.6 2.0 0.3 0.7 1.2 2.2 Balance as of March 31st $ (2.8 ) $ 0.9 $ (61.2 ) $ (63.1 ) $ (4.1 ) $ 0.2 $ (53.9 ) $ (57.8 ) 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, 2020
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, 2020 and December 31, 2019 Issued as of Par Value March 31, 2020 December 31, 2019 Eversource $ 5 380,000,000 351,818,402 345,858,402 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 Common Share Issuance and Forward Sale Agreement: In June 2019, Eversource completed an equity offering consisting of 5,980,000 common shares issued directly by the Company and 11,960,000 common shares issuable pursuant to a forward sale agreement with an investment bank. Under the forward sale agreement, 11,960,000 common shares were borrowed from third parties and sold by the underwriters. The forward sale agreement allowed Eversource, at its election and prior to May 29, 2020, to physically settle the forward sale agreement by issuing common shares in exchange for net proceeds at the then-applicable forward sale price specified by the agreement (initially, $71.48 per share) or, alternatively, to settle the forward sale agreement in whole or in part through the delivery or receipt of shares or cash. The forward sale price was subject to adjustment daily based on a floating interest rate factor and would decrease in respect of certain fixed amounts specified in the agreement, such as dividends. Eversource previously issued 6,000,000 common shares under the forward sale agreement in December 2019. On March 23, 2020, Eversource physically settled a portion of the forward sale agreement by delivering 1,500,000 common shares in exchange for net proceeds of $105.7 million . Subsequently, on March 26, 2020, Eversource physically settled the remaining portion of the forward sale agreement by delivering 4,460,000 common shares in exchange for net proceeds of $314.1 million . The forward sale price used to determine the cash proceeds received by Eversource was calculated based on the initial forward sale price of $71.48 per share, as adjusted in accordance with the forward sale agreement. The 2020 issuances of 5,960,000 common shares resulted in proceeds of $419.8 million , net of issuance costs, and were reflected in shareholders' equity and as financing activities on the statement of cash flows. Issuances of shares under the forward sale agreement are classified as equity transactions. Accordingly, no amounts relating to the forward sale agreement were recorded in the financial statements until settlements took place. Prior to any settlements, the only impact to the financial statements was the inclusion of incremental shares within the calculation of diluted EPS using the treasury stock method. See Note 14, "Earnings Per Share," to the financial statements for information on the forward sale agreement’s impact on the calculation of diluted EPS. Eversource used the net proceeds received upon the direct issuance of common shares and the net proceeds received upon settlement of the forward sale agreement to repay short-term debt under the commercial paper program, to fund capital spending and clean energy initiatives, and for general corporate purposes. Treasury Shares: As of March 31, 2020 and December 31, 2019 , there were 15,407,215 and 15,977,757 Eversource common shares held as treasury shares, respectively. As of March 31, 2020 and December 31, 2019 , Eversource common shares outstanding were 336,411,187 and 329,880,645 , respectively. Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for each of the three months ended March 31, 2020 and 2019 . 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, 2020 and December 31, 2019 . 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, 2020
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, 2020 and December 31, 2019 Issued as of Par Value March 31, 2020 December 31, 2019 Eversource $ 5 380,000,000 351,818,402 345,858,402 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 Common Share Issuance and Forward Sale Agreement: In June 2019, Eversource completed an equity offering consisting of 5,980,000 common shares issued directly by the Company and 11,960,000 common shares issuable pursuant to a forward sale agreement with an investment bank. Under the forward sale agreement, 11,960,000 common shares were borrowed from third parties and sold by the underwriters. The forward sale agreement allowed Eversource, at its election and prior to May 29, 2020, to physically settle the forward sale agreement by issuing common shares in exchange for net proceeds at the then-applicable forward sale price specified by the agreement (initially, $71.48 per share) or, alternatively, to settle the forward sale agreement in whole or in part through the delivery or receipt of shares or cash. The forward sale price was subject to adjustment daily based on a floating interest rate factor and would decrease in respect of certain fixed amounts specified in the agreement, such as dividends. Eversource previously issued 6,000,000 common shares under the forward sale agreement in December 2019. On March 23, 2020, Eversource physically settled a portion of the forward sale agreement by delivering 1,500,000 common shares in exchange for net proceeds of $105.7 million . Subsequently, on March 26, 2020, Eversource physically settled the remaining portion of the forward sale agreement by delivering 4,460,000 common shares in exchange for net proceeds of $314.1 million . The forward sale price used to determine the cash proceeds received by Eversource was calculated based on the initial forward sale price of $71.48 per share, as adjusted in accordance with the forward sale agreement. The 2020 issuances of 5,960,000 common shares resulted in proceeds of $419.8 million , net of issuance costs, and were reflected in shareholders' equity and as financing activities on the statement of cash flows. Issuances of shares under the forward sale agreement are classified as equity transactions. Accordingly, no amounts relating to the forward sale agreement were recorded in the financial statements until settlements took place. Prior to any settlements, the only impact to the financial statements was the inclusion of incremental shares within the calculation of diluted EPS using the treasury stock method. See Note 14, "Earnings Per Share," to the financial statements for information on the forward sale agreement’s impact on the calculation of diluted EPS. Eversource used the net proceeds received upon the direct issuance of common shares and the net proceeds received upon settlement of the forward sale agreement to repay short-term debt under the commercial paper program, to fund capital spending and clean energy initiatives, and for general corporate purposes. Treasury Shares: As of March 31, 2020 and December 31, 2019 , there were 15,407,215 and 15,977,757 Eversource common shares held as treasury shares, respectively. As of March 31, 2020 and December 31, 2019 , Eversource common shares outstanding were 336,411,187 and 329,880,645 , respectively. Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for each of the three months ended March 31, 2020 and 2019 . 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, 2020 and December 31, 2019 . 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, 2020
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 and the equity forward sale agreement, as if they were converted into outstanding common shares. The dilutive effect of unvested RSU and performance share awards, as well as the equity forward sale agreement, 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. As described in Note 12, "Common Shares," earnings per share dilution, if any, related to the forward sale agreement is determined under the treasury stock method until settlement of the forward sale agreement. Under this method, the number of Eversource common shares used in calculating diluted EPS is deemed to be increased by the excess, if any, of the number of shares that would be issued upon physical settlement of the forward sale agreement less the number of shares that would be purchased by Eversource in the market (based on the average market pri ce during the same reporting period) using the proceeds receivable upon settlement (based on the adjusted forward sale price at the end of that reporting period). Share dilution occurs when the average market price of Eversource's common shares is higher than the adjusted forward sale price. 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, 2020 March 31, 2019 Net Income Attributable to Common Shareholders $ 334.8 $ 308.7 Weighted Average Common Shares Outstanding: Basic 331,102,237 317,624,593 Dilutive Effect of: Share-Based Compensation Awards and Other 747,233 691,489 Equity Forward Sale Agreement 1,087,683 — Total Dilutive Effect 1,834,916 691,489 Diluted 332,937,153 318,316,082 Basic and Diluted EPS $ 1.01 $ 0.97

REVENUES

REVENUES	3 Months Ended
	Mar. 31, 2020
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, 2020 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 $ 963.8 $ 238.0 $ — $ 27.8 $ — $ — $ 1,229.6 Commercial 607.0 134.6 — 14.8 — (1.0 ) 755.4 Industrial 79.8 28.3 — 1.1 — (3.2 ) 106.0 Total Retail Tariff Sales Revenues 1,650.6 400.9 — 43.7 — (4.2 ) 2,091.0 Wholesale Transmission Revenues — — 336.3 — 17.3 (283.6 ) 70.0 Wholesale Market Sales Revenues 91.0 13.2 — 0.8 — — 105.0 Other Revenues from Contracts with Customers 19.1 0.9 3.4 1.9 277.3 (276.2 ) 26.4 Amortization/(Reserve) for Revenues Subject to Refund 2.3 0.5 — (0.8 ) — — 2.0 Total Revenues from Contracts with Customers 1,763.0 415.5 339.7 45.6 294.6 (564.0 ) 2,294.4 Alternative Revenue Programs (1) 38.8 32.2 29.8 1.1 — (27.4 ) 74.5 Other Revenues (2) 3.5 0.9 0.2 0.2 — — 4.8 Total Operating Revenues $ 1,805.3 $ 448.6 $ 369.7 $ 46.9 $ 294.6 $ (591.4 ) $ 2,373.7 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 Amortization/(Reserve) for Revenues (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 (1) 2.1 10.4 12.4 0.9 — (11.1 ) 14.7 Other Revenues (2) 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, 2020 For the Three Months Ended March 31, 2019 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Revenues from Contracts with Customers Retail Tariff Sales Residential $ 489.9 $ 331.0 $ 142.9 $ 510.5 $ 371.0 $ 151.8 Commercial 226.4 301.9 79.1 236.7 336.5 79.8 Industrial 34.0 26.8 19.0 34.6 28.8 18.7 Total Retail Tariff Sales Revenues 750.3 659.7 241.0 781.8 736.3 250.3 Wholesale Transmission Revenues 151.8 134.8 49.7 154.8 122.6 47.5 Wholesale Market Sales Revenues 64.7 14.4 11.9 13.7 24.4 13.4 Other Revenues from Contracts with Customers 8.8 10.7 3.7 8.9 4.0 3.6 Amortization/(Reserve) for Revenues — — 2.3 — — (3.1 ) Total Revenues from Contracts with Customers 975.6 819.6 308.6 959.2 887.3 311.7 Alternative Revenue Programs (1) 44.6 19.3 4.7 5.7 7.3 1.5 Other Revenues (2) 1.7 1.4 0.6 1.0 1.5 0.3 Eliminations (122.2 ) (106.5 ) (37.5 ) (116.7 ) (98.5 ) (37.1 ) Total Operating Revenues $ 899.7 $ 733.8 $ 276.4 $ 849.2 $ 797.6 $ 276.4 (1) CL&P, NSTAR Electric, Yankee Gas, NSTAR Gas and the Connecticut water distribution business each have a revenue decoupling mechanism approved by a regulatory commission. The revenue decoupling mechanisms mitigate the im pact of lower demand and resulting lost sales revenues by allowing for a true-up to occur as part of each company’s annual decoupling filing. These revenue decoupling mechanisms qualify as alternative revenue programs in accordance with accounting guidance for rate-regulated operations. The increase in revenues from Alternative Revenue Programs for the three months ended March 31, 2020, as compared to the three months ended March 31, 2019, was primarily the result of a higher decoupling deferral adjustment driven by lower distribution sales volumes in the first quarter of 2020. The decoupling deferral adjustment to revenues is recorded as a regulatory tracker mechanism within Regulatory Assets on the balance sheets. (2) Other Revenues include certain fees charged to customers that are not considered revenue from contracts with customers. Other revenues also includes lease revenues under lessor accounting guidance of $1.1 million (including $0.2 million at CL&P, and $0.7 million at NSTAR Electric) and $1.0 million (including $0.2 million at CL&P, and $0.6 million at NSTAR Electric) for the three months ended March 31, 2020 and March 31, 2019 , respectively.

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2020
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 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, 5) the results of other unregulated subsidiaries, which are not part of its core business, and 6) Eversource parent's equity ownership interests that are not consolidated, which primarily include the offshore wind business, a natural gas pipeline owned by Enbridge, Inc., and a renewable energy investment fund. 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 $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, 2020 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 1,805.3 $ 448.6 $ 369.7 $ 46.9 $ 294.6 $ (591.4 ) $ 2,373.7 Depreciation and Amortization (167.3 ) (19.1 ) (67.5 ) (11.4 ) (21.3 ) 0.6 (286.0 ) Other Operating Expenses (1,439.6 ) (311.6 ) (106.8 ) (25.0 ) (257.0 ) 591.4 (1,548.6 ) Operating Income $ 198.4 $ 117.9 $ 195.4 $ 10.5 $ 16.3 $ 0.6 $ 539.1 Interest Expense $ (53.1 ) $ (11.4 ) $ (30.6 ) $ (8.7 ) $ (42.7 ) $ 11.8 $ (134.7 ) Other Income, Net 12.5 1.4 5.2 0.1 468.1 (463.2 ) 24.1 Net Income Attributable to Common Shareholders 130.1 84.4 126.8 2.1 442.2 (450.8 ) 334.8 Cash Flows Used for Investments in Plant 315.8 99.1 232.8 18.5 59.3 — 725.5 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 (1) 279.3 87.4 184.8 20.7 55.9 — 628.1 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, 2020 $ 23,135.9 $ 4,430.4 $ 11,137.5 $ 2,368.7 $ 20,860.8 $ (20,284.3 ) $ 41,649.0 As of December 31, 2019 22,541.9 4,345.5 10,904.0 2,351.7 20,469.6 (19,488.8 ) 41,123.9 (1) See Note 1A, "Summary of Significant Accounting Policies - Basis of Presentation," for information regarding the correction of cash investments in plant reported in 2019.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2020
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 2019 Form 10-K, which was filed with the SEC on February 27, 2020. 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, 2020 and December 31, 2019 , and the results of operations, comprehensive income, common shareholders' equity, and cash flows for the three months ended March 31, 2020 and 2019 . The results of operations, comprehensive income, and cash flows for the three months ended March 31, 2020 and 2019 are not necessarily indicative of the results expected for a full year. Eversource consolidates the operations of CYAPC and YAEC, both of which are inactive regional nuclear power companies engaged in the long-term storage of their spent nuclear fuel. 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 holds several equity ownership interests that are not consolidated and are accounted for under the equity method. 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. In March 2020, the World Health Organization declared the outbreak of the 2019 novel coronavirus (COVID-19) a pandemic and President Trump declared a national emergency affecting the entire United States where each state qualifies as being part of a national disaster. The spread of COVID-19 has adversely affected workforces, the overall economy and caused significant volatility in the financial markets. To date, Eversource has not experienced significant operational or financial impacts directly related to the pandemic. Due to the inherent uncertainty of the unprecedented and rapidly evolving situation, management will continue to closely monitor how COVID-19 related developments affect Eversource. As of the date of our filing and based on information available, management is unable to predict the impacts that the COVID-19 pandemic will have on future operations, financial position, results of operations, and cash flows. The extent of the impact in the future will vary and depend in large part on the duration, scope and severity of a national and global economic slowdown, risk of inflation, governmental and regulatory actions, the maintenance of a strong regional and national healthcare system, and the continued spread of the virus, which is mitigated through social distancing measures. Our customer receivable balances and uncollectible accounts have not been materially impacted by COVID-19. We believe that we will be able to develop a successful structure with our respective state regulatory commissions to recover our costs associated with COVID-19, while balancing the impact on our customers’ bills. See Note 1C, "Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts," for further discussion of our evaluation of the allowance for doubtful accounts as of March 31, 2020 in light of the COVID-19 pandemic. An extended economic slowdown could result in lower demand for electricity, natural gas and/or water by our commercial and industrial customers. However, fluctuations in retail sales volumes for CL&P, NSTAR Electric, Yankee Gas, NSTAR Gas and our Connecticut water distribution business are not expected to materially impact earnings due to their respective regulatory commission-approved distribution revenue decoupling mechanisms. The revenue decoupling mechanisms mitigate the im pact of lower demand and resulting lost sales revenues by allowing for a true-up to occur as part of each company’s annual decoupling filing. These revenue decoupling mechanisms qualify as alternative revenue programs in accordance with accounting guidance for rate-regulated operations. As of March 31, 2020, we did not have indicators of triggering events for impairments to our goodwill, long-lived assets, available-for-sale debt securities, or equity method investment carrying values. Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation. The Eversource and PSNH 2019 statements of cash flows and the 2019 segment footnote were revised to correct an error in the presentation of non-cash capital additions. The impact of this revision on the statement of cash flows is a decrease to operating cash inflows in Accounts Payable of $46.6 million and a corresponding decrease to investing cash outflows in Investments in Property, Plant and Equipment for the quarter ended March 31, 2019. This revision is not deemed material, individually or in the aggregate, to the previously issued financial statements.
Accounting Standards	Accounting Standards Accounting Standards Issued but Not Yet Effective: In December 2019, the FASB issued Accounting Standards Update (ASU) 2019-12, Income Taxes (Topic 740) - Simplifying the Accounting for Income Taxes , which eliminates certain exceptions to the general principles of current income tax guidance in ASC 740 and simplifies and improves consistency in application of that income tax guidance through clarifications of and amendments to ASC 740. The guidance is effective in the first quarter of 2021. The ASU is not expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric and PSNH. Accounting Standards Recently Adopted: On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a model for recognizing credit losses on financial instruments based on an estimate of current expected losses, requiring immediate recognition of credit losses expected over the life of a financial instrument. The Company determined the impacts of this standard on the allowance for credit losses on its financial instruments, primarily accounts receivable. As of January 1, 2020, the Company recorded increases to the allowance for uncollectible accounts for late fees and other receivable amounts of $1.6 million , $0.9 million , $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively. The impact to retained earnings, net of tax, was $1.5 million , $0.9 million , $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively. The Company also adjusted the allowance for uncollectible amounts of hardship receivables and other low-income assistance programs, which are ultimately collectible in rates at specified points in time under approved regulatory mechanisms. The impact on the allowance, which was offset in other long-term assets on the balance sheets, was an increase of $22.2 million and $21.3 million at Eversource and CL&P, respectively, and a decrease of $1.5 million at NSTAR Electric. See Note 1C, “Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts,” for further information. The Company adopted ASU 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment as of January 1, 2020 . The ASU simplified the accounting for goodwill impairment by removing a complex step in the goodwill impairment test. Under the guidance, goodwill impairment is measured as the amount by which its carrying value exceeds its fair value. The ASU is not expected to have an impact on the financial statements of Eversource. On January 1, 2020, the Company adopted ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The ASU aligned the requirements for capitalizing costs incurred to implement a cloud computing arrangement with existing internal-use software guidance. The prospective implementation of this standard did not have any impact on the financial statements of Eversource, CL&P, NSTAR Electric or PSNH for the period ending March 31, 2020 . On January 1, 2020, the Company prospectively adopted ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement . The ASU modified fair value disclosure requirements . The standard includes new disclosure requirements for Level 3 unobservable inputs and eliminated the requirement to disclose certain information relating to transfers between levels. The modified disclosures are included in Note 1D, “Summary of Significant Accounting Policies - Fair Value Measurements,” and Note 4, “Derivative Instruments.”
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts Receivables, Net on the balance sheets primarily i ncludes trade receivables from retail customers and customers related to wholesale transmission contracts, wholesale market sales, sales of RECs and property rentals. Receivables, Net also includes customer receivables for the purchase of electricity from a competitive third party supplier, the current portion of customer energy efficiency loans, property damage receivables and other miscellaneous receivables. There is no material concentration of receivables. Receivables are recorded at amortized cost, net of a credit loss provision (or allowance for uncollectible accounts). Receivables are presented net of expected credit losses at estimated net realizable value by maintaining an allowance for uncollectible accounts. Effective January 1, 2020, the current expected credit loss (CECL) model was applied to receivables for purposes of calculating the allowance for uncollectible accounts. This model is based on expected losses and results in the recognition of estimated expected credit losses, including uncollectible amounts for both billed and unbilled revenues, over the life of the receivable at the time a receivable is recorded. The allowance for uncollectible accounts is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. Factors in determining credit loss include historical collection, write-off experience, and management's assessment of collectibility from customers, including current conditions, reasonable forecasts, and expectations of future collectibility and collection efforts. Management continuously assesses the collectibility of receivables and adjusts estimates based on actual experience and future expectations based on economic indicators. Management also monitors the aging analysis of receivables to determine if there are changes in the collections of accounts receivable. Receivable balances are written off against the allowance for uncollectible accounts when the customer accounts are no longer in service and these balances are deemed to be uncollectible. As of March 31, 2020, management evaluated the adequacy of the allowance for uncollectible accounts in light of the COVID-19 pandemic and the economic downturn to date. This evaluation included an analysis of collection and customer payment trends in 2020, economic conditions, flexible payment plans and financial hardship arrearage management programs being offered to customers, and the impacts of federal governmental pandemic relief programs for our customers and the expansion of unemployment benefits initiatives, which help to mitigate the potential for increasing customer account delinquencies. Additionally, management considered past economic declines and corresponding uncollectible reserves as part of the current assessment. Based upon the evaluation performed, management concluded that the reserve balance as of March 31, 2020 adequately reflected the collection risk and net realizable value for Eversource’s receivables. Management will continue to evaluate the adequacy of the uncollectible allowance in future reporting periods based on an ongoing assessment of accounts receivable collections, delinquency statistics, and analysis of aging-based quantitative assessments. 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. Hardship customers are protected from shut-off in certain circumstances, and historical collection experience has reflected a higher default risk as compared to the rest of the receivable population. As a result of the adoption of ASU 2016-13, management aligned the allowance for uncollectible hardship accounts across all regulatory jurisdictions, using a higher credit risk profile for this pool of trade receivables as compared to non-hardship receivables. Implementation impacts of the accounting standard on the allowance for uncollectible hardship accounts are reflected in the rollforward of the uncollectible allowance in the table below. The allowance for uncollectible hardship accounts is included in the total uncollectible allowance balance.
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, long-lived assets 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. 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 TaxesEversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers. Separate from above were amounts recorded as Taxes Other Than Income Taxes at CL&P related to the remittance to the State of Connecticut of energy efficiency funds collected from customers of $10.7 million for the three months ended March 31, 2019. Energy efficiency funds collected from customers after July 1, 2019 are no longer subject to remittance to the State of Connecticut. These amounts were 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. 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.
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 and the equity forward sale agreement, as if they were converted into outstanding common shares. The dilutive effect of unvested RSU and performance share awards, as well as the equity forward sale agreement, 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. As described in Note 12, "Common Shares," earnings per share dilution, if any, related to the forward sale agreement is determined under the treasury stock method until settlement of the forward sale agreement. Under this method, the number of Eversource common shares used in calculating diluted EPS is deemed to be increased by the excess, if any, of the number of shares that would be issued upon physical settlement of the forward sale agreement less the number of shares that would be purchased by Eversource in the market (based on the average market pri ce during the same reporting period) using the proceeds receivable upon settlement (based on the adjusted forward sale price at the end of that reporting period). Share dilution occurs when the average market price of Eversource's common shares is higher than the adjusted forward sale price.
Restricted Cash	Special Deposits represent cash collections related to the PSNH RRB customer charges that are held in trust, required ISO-NE cash deposits, and CYAPC and YAEC cash balances. Special Deposits are included in Current Assets on the balance sheets. Restricted 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 obligations.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Allowance for Uncollectible Accounts	The activity in the allowance for uncollectible accounts by portfolio segment is as follows: For the Three Months Ended March 31, 2020 Eversource CL&P NSTAR Electric PSNH (Millions of Dollars) Hardship Accounts Retail (Non-Hardship), Wholesale, and Other Receivables Total Allowance Hardship Accounts Retail (Non-Hardship), Wholesale and Other Receivables Total Allowance Hardship Accounts Retail (Non-Hardship), Wholesale, and Other Receivables Total Allowance Total Allowance Beginning Balance $ 143.3 $ 81.5 $ 224.8 $ 80.1 $ 17.2 $ 97.3 $ 43.9 $ 31.5 $ 75.4 $ 10.5 ASU 2016-13 Implementation Impact on January 1, 2020 21.6 2.2 23.8 21.3 0.9 22.2 (1.6 ) 0.3 (1.3 ) 0.3 Uncollectible Expense (1) — 11.4 11.4 — 3.2 3.2 — 3.7 3.7 0.7 Uncollectible Costs Deferred (2) 11.8 8.5 20.3 12.9 1.8 14.7 (3.4 ) 3.4 — 1.3 Write-Offs (4.7 ) (16.8 ) (21.5 ) (3.8 ) (3.5 ) (7.3 ) (0.4 ) (8.0 ) (8.4 ) (1.7 ) Recoveries Collected 0.2 3.1 3.3 0.2 0.6 0.8 — 1.7 1.7 0.1 Ending Balance $ 172.2 $ 89.9 $ 262.1 $ 110.7 $ 20.2 $ 130.9 $ 38.5 $ 32.6 $ 71.1 $ 11.2 (1) Uncollectible expense associated with customer and other accounts receivable is included in Operations and Maintenance expense on the statements of income. For the three months ended March 31, 2019 , uncollectible expense included in Operations and Maintenance Expense was $18.6 million , $4.1 million , $6.0 million and $1.7 million for Eversource, CL&P, NSTAR Electric and PSNH, respectively. (2) The current period provision for expected credit losses for hardship accounts and other customer receivables that are ultimately recovered in rates is deferred as a regulatory cost on the balance sheets.
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, 2020 March 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Pension, SERP and PBOP Non-Service Income/(Expense) Components $ 12.7 $ 1.1 $ 7.9 $ 1.9 $ 7.4 $ (0.6 ) $ 7.0 $ 0.5 AFUDC Equity 10.6 3.9 5.0 1.5 10.9 2.6 4.0 0.2 Equity in Earnings of Unconsolidated Affiliates 4.0 — 0.1 — 5.0 — 0.2 — Investment Income/(Loss) (4.3 ) (3.4 ) (1.3 ) (0.5 ) 1.2 1.7 (0.3 ) 0.4 Interest Income 0.7 0.3 0.1 0.3 6.5 0.4 0.2 5.9 Other 0.4 — 0.4 — — (0.2 ) — — Total Other Income, Net $ 24.1 $ 1.9 $ 12.2 $ 3.2 $ 31.0 $ 3.9 $ 11.1 $ 7.0
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, 2020 March 31, 2019 Eversource $ 43.1 $ 45.0 CL&P 35.5 36.2
Non-cash Investing Activities	Non-cash investing activities include plant additions included in Accounts Payable as follows: (Millions of Dollars) As of March 31, 2020 As of March 31, 2019 Eversource $ 273.7 $ 336.3 CL&P 85.0 121.9 NSTAR Electric 70.2 83.2 PSNH 37.9 30.4
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, 2020 As of December 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Cash as reported on the Balance Sheets $ 47.4 $ 3.8 $ 2.8 $ — $ 15.4 $ — $ 0.1 $ 0.4 Restricted cash included in: Special Deposits 39.0 4.7 6.2 16.6 52.5 4.6 6.2 32.5 Marketable Securities 44.1 0.3 0.1 0.6 46.0 0.4 — 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 $ 133.7 $ 8.8 $ 9.1 $ 20.4 $ 117.1 $ 5.0 $ 6.3 $ 36.7

REGULATORY ACCOUNTING (Tables)

REGULATORY ACCOUNTING (Tables)	3 Months Ended
	Mar. 31, 2020
Regulated Operations [Abstract]
Components of Regulatory Assets	The components of regulatory assets were as follows: As of March 31, 2020 As of December 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Benefit Costs $ 2,334.3 $ 528.3 $ 616.3 $ 213.9 $ 2,382.9 $ 539.0 $ 629.8 $ 218.2 Income Taxes, Net 727.2 458.9 108.5 12.8 725.8 458.8 108.0 12.8 Securitized Stranded Costs 554.5 — — 554.5 565.3 — — 565.3 Storm Restoration Costs, Net 497.6 251.6 183.0 63.0 540.6 274.6 200.6 65.4 Regulatory Tracker Mechanisms 551.5 191.0 227.4 84.6 411.5 78.3 207.1 65.8 Derivative Liabilities 335.2 333.8 — — 334.5 329.2 — — Goodwill-related 327.3 — 281.0 — 331.5 — 284.6 — Asset Retirement Obligations 99.3 31.2 51.5 3.7 97.2 30.8 50.3 3.6 Other Regulatory Assets 136.5 24.8 61.6 13.8 125.4 25.2 55.2 14.7 Total Regulatory Assets 5,563.4 1,819.6 1,529.3 946.3 5,514.7 1,735.9 1,535.6 945.8 Less: Current Portion 785.1 290.6 304.0 102.4 651.1 178.6 285.6 84.1 Total Long-Term Regulatory Assets $ 4,778.3 $ 1,529.0 $ 1,225.3 $ 843.9 $ 4,863.6 $ 1,557.3 $ 1,250.0 $ 861.7
Components of Regulatory Liabilities	The components of regulatory liabilities were as follows: As of March 31, 2020 As of December 31, 2019 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH EDIT due to Tax Cuts and Jobs Act $ 2,831.2 $ 1,019.8 $ 1,063.9 $ 391.4 $ 2,844.6 $ 1,022.8 $ 1,071.2 $ 392.8 Cost of Removal 579.3 77.4 337.2 14.8 559.8 64.6 330.6 16.3 Benefit Costs 80.1 — 68.6 — 84.5 — 72.2 — Regulatory Tracker Mechanisms 412.5 121.7 189.8 64.1 325.1 94.8 165.6 57.0 AFUDC - Transmission 74.4 45.7 28.7 — 73.2 46.0 27.2 — Other Regulatory Liabilities 130.6 34.4 47.4 10.7 132.0 19.6 59.0 13.1 Total Regulatory Liabilities 4,108.1 1,299.0 1,735.6 481.0 4,019.2 1,247.8 1,725.8 479.2 Less: Current Portion 439.9 119.3 219.9 69.0 361.2 82.8 209.2 65.8 Total Long-Term Regulatory Liabilities $ 3,668.2 $ 1,179.7 $ 1,515.7 $ 412.0 $ 3,658.0 $ 1,165.0 $ 1,516.6 $ 413.4

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 (Millions of Dollars) Distribution - Electric $ 16,117.4 $ 15,880.0 Distribution - Natural Gas 3,984.2 3,931.1 Transmission - Electric 11,059.4 10,958.4 Distribution - Water 1,730.2 1,726.5 Solar 200.5 200.2 Utility 33,091.7 32,696.2 Other (1) 1,073.2 1,025.6 Property, Plant and Equipment, Gross 34,164.9 33,721.8 Less: Accumulated Depreciation Utility (7,572.4 ) (7,483.5 ) Other (408.0 ) (387.4 ) Total Accumulated Depreciation (7,980.4 ) (7,870.9 ) Property, Plant and Equipment, Net 26,184.5 25,850.9 Construction Work in Progress 1,856.9 1,734.6 Total Property, Plant and Equipment, Net $ 28,041.4 $ 27,585.5 As of March 31, 2020 As of December 31, 2019 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Distribution - Electric $ 6,607.8 $ 7,250.8 $ 2,299.1 $ 6,485.5 $ 7,163.7 $ 2,271.1 Transmission - Electric 5,094.1 4,444.7 1,515.8 5,043.0 4,411.9 1,498.7 Solar — 200.5 — — 200.2 — Property, Plant and Equipment, Gross 11,701.9 11,896.0 3,814.9 11,528.5 11,775.8 3,769.8 Less: Accumulated Depreciation (2,413.6 ) (2,925.2 ) (810.1 ) (2,385.7 ) (2,895.3 ) (799.9 ) Property, Plant and Equipment, Net 9,288.3 8,970.8 3,004.8 9,142.8 8,880.5 2,969.9 Construction Work in Progress 472.6 643.8 182.5 483.0 592.3 159.6 Total Property, Plant and Equipment, Net $ 9,760.9 $ 9,614.6 $ 3,187.3 $ 9,625.8 $ 9,472.8 $ 3,129.5 (1) These assets are primarily comprised of computer software, hardware and equipment at Eversource Service and buildings at The Rocky River Realty Company.

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 (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 $ 12.8 $ (0.4 ) $ 12.4 $ 12.2 $ (0.4 ) $ 11.8 Long-Term Derivative Assets: CL&P Level 3 68.2 (2.1 ) 66.1 67.5 (2.1 ) 65.4 Current Derivative Liabilities: CL&P Level 3 (69.6 ) — (69.6 ) (67.8 ) — (67.8 ) Other Level 2 (1.4 ) 0.3 (1.1 ) (5.2 ) — (5.2 ) Long-Term Derivative Liabilities: CL&P Level 3 (342.7 ) — (342.7 ) (338.6 ) — (338.6 ) Other Level 2 (0.3 ) — (0.3 ) (0.1 ) — (0.1 ) (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 Unobservable Inputs Used	The following is a summary of 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, 2020 As of December 31, 2019 CL&P Range Weighted Average (1) Period Covered Range Period Covered Capacity Prices $ 4.30 — $5.82 $ 4.81 per kW-Month 2024 - 2026 $ 3.01 — $7.34 per kW-Month 2023 - 2026 Forward Reserve Prices 0.80 — 1.90 1.35 per kW-Month 2020 - 2024 0.80 — 1.90 per kW-Month 2020 - 2024 (1) Unobservable inputs were weighted by the relative future capacity and forward reserve prices and contractual MWs over the periods covered.
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) 2020 2019 Derivatives, Net: Fair Value as of Beginning of Period $ (329.2 ) $ (356.5 ) Net Realized/Unrealized Losses Included in Regulatory Assets (16.4 ) (5.3 ) Settlements 11.8 8.7 Fair Value as of End of Period $ (333.8 ) $ (353.1 )

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 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 $ 224.2 $ 10.9 $ (0.6 ) $ 234.5 $ 228.4 $ 5.8 $ (0.1 ) $ 234.1
Contractual Maturities of Available-for-Sale Debt Securities	As of March 31, 2020 , 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) $ 56.5 $ 56.6 One to five years 40.1 41.7 Six to ten years 38.6 41.4 Greater than ten years 89.0 94.8 Total Debt Securities $ 224.2 $ 234.5 (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, 2020 As of December 31, 2019 Level 1: Mutual Funds and Equities $ 196.8 $ 228.5 Money Market Funds 44.1 46.0 Total Level 1 $ 240.9 $ 274.5 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 100.9 $ 96.8 Corporate Debt Securities 45.9 44.0 Asset-Backed Debt Securities 13.7 12.9 Municipal Bonds 22.2 26.7 Other Fixed Income Securities 7.7 7.7 Total Level 2 $ 190.4 $ 188.1 Total Marketable Securities $ 431.3 $ 462.6

SHORT-TERM AND LONG-TERM DEBT (

SHORT-TERM AND LONG-TERM DEBT (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 December 31, 2019 March 31, 2020 December 31, 2019 March 31, 2020 December 31, 2019 (Millions of Dollars) Eversource Parent Commercial Paper Program $ 738.4 $ 1,224.9 $ 711.6 $ 225.1 3.38 % 1.98 % NSTAR Electric Commercial Paper Program 88.0 10.5 562.0 639.5 1.25 % 1.63 %
Summary of Long-Term Debt Issuance and Repayments	The following table summarizes long-term debt issuances and repayments: (Millions of Dollars) Issuance/(Repayment) Issue Date or Repayment Date Maturity Date Use of Proceeds for Issuance/ NSTAR Electric: 3.95% 2020 Debentures $ 400.0 March 2020 April 2030 Refinanced investments in eligible green expenditures, which were previously financed in 2018 and 2019 5.10% Series E Senior Notes (95.0 ) March 2020 March 2020 Paid at maturity Other: Eversource Parent 3.45% Series P Senior Notes 350.0 January 2020 January 2050 Paid short-term borrowings NSTAR Gas 4.46% Series N First Mortgage Bonds (125.0 ) January 2020 January 2020 Paid at maturity Yankee Gas 4.87% Series K First Mortgage Bonds (50.0 ) April 2020 April 2020 Paid at maturity NSTAR Gas 2.33% Series R First Mortgage Bonds 75.0 May 2020 May 2025 Refinanced existing indebtedness, funded capital expenditures and for general corporate purposes NSTAR Gas 3.15% Series S First Mortgage Bonds 115.0 May 2020 May 2050 Refinanced existing indebtedness, funded capital expenditures and for general corporate purposes

RATE REDUCTION BONDS AND VARI_2

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 Restricted Cash - Current Portion (included in Current Assets) $ 16.6 $ 32.5 Restricted Cash - Long-Term Portion (included in Other Long-Term Assets) 3.2 3.2 Securitized Stranded Cost (included in Regulatory Assets) 554.5 565.3 Other Regulatory Liabilities (included in Regulatory Liabilities) 6.0 5.6 Accrued Interest (included in Other Current Liabilities) 3.3 8.6 Rate Reduction Bonds - Current Portion 43.2 43.2 Rate Reduction Bonds - Long-Term Portion 518.5 540.1 (Millions of Dollars) For the Three Months Ended Income Statement: March 31, 2020 March 31, 2019 Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net) $ 10.8 $ 10.6 Interest Expense on RRB Principal (included in Interest Expense) 5.0 5.4

PENSION BENEFITS AND POSTRETI_2

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION (Tables)	3 Months Ended
	Mar. 31, 2020
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/(income), less the capitalized portion, is included in Operations and Maintenance expense on the statements of income. The remaining components of net periodic benefit expense/(income), less the deferred portion, 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 PBOP For the Three Months Ended March 31, 2020 For the Three Months Ended March 31, 2020 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 19.6 $ 5.7 $ 3.8 $ 2.2 $ 2.6 $ 0.5 $ 0.6 $ 0.2 Interest Cost 44.3 9.5 9.6 4.9 6.1 1.2 1.7 0.6 Expected Return on Plan Assets (100.3 ) (20.0 ) (25.8 ) (11.3 ) (18.1 ) (2.4 ) (8.5 ) (1.4 ) Actuarial Loss 49.3 10.0 13.3 4.1 2.1 0.4 0.7 0.1 Prior Service Cost/(Credit) 0.3 — 0.1 — (5.4 ) 0.2 (4.2 ) 0.1 Total Net Periodic Benefit Expense/(Income) $ 13.2 $ 5.2 $ 1.0 $ (0.1 ) $ (12.7 ) $ (0.1 ) $ (9.7 ) $ (0.4 ) Intercompany Allocations N/A $ 1.9 $ 1.9 $ 0.6 N/A $ (0.4 ) $ (0.4 ) $ (0.2 ) Pension and SERP PBOP For the Three Months Ended March 31, 2019 For the Three Months Ended March 31, 2019 (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 $ 2.1 $ 0.4 $ 0.4 $ 0.2 Interest Cost 54.2 11.5 11.9 6.2 8.1 1.5 2.3 0.9 Expected Return on Plan Assets (92.3 ) (18.8 ) (24.4 ) (10.3 ) (16.6 ) (2.3 ) (7.5 ) (1.3 ) Actuarial Loss 35.8 8.1 9.4 3.5 2.5 0.4 0.9 0.2 Prior Service Cost/(Credit) 1.1 — 0.1 — (5.8 ) 0.3 (4.2 ) 0.1 Total Net Periodic Benefit Expense/(Income) $ 18.1 $ 5.6 $ 0.9 $ 2.0 $ (9.7 ) $ 0.3 $ (8.1 ) $ 0.1 Intercompany Allocations N/A $ 7.8 $ 3.0 $ 2.4 N/A $ (0.1 ) $ (0.2 ) $ (0.1 )

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 As of December 31, 2019 Number of Sites Reserve (in millions) Number of Sites Reserve (in millions) Eversource 55 $ 79.1 57 $ 81.0 CL&P 15 11.8 15 11.4 NSTAR Electric 13 6.2 15 8.0 PSNH 9 7.4 9 7.5
Summary of Exposure to Guarantees and Indemnifications	The following table summarizes Eversource parent's exposure to guarantees and indemnifications of its subsidiaries and affiliates to external parties as of March 31, 2020 : Company Description Maximum Exposure (in millions) Expiration Dates Various Surety Bonds (1) $ 30.0 2020 - 2023 Rocky River Realty Company and Eversource Service Lease Payments for Real Estate 6.1 2024 Bay State Wind LLC Real Estate Purchase 2.5 2020 Sunrise Wind LLC Offshore Wind (2) 2.2 - (1) Surety bond expiration dates reflect termination dates, the majority of which will be renewed or extended. Certain surety bonds contain credit ratings triggers that would require Eversource parent to post collateral in the event that the unsecured debt credit ratings of Eversource parent are downgraded. (2) On October 25, 2019, Eversource parent issued a guaranty on behalf of its 50 percent -owned affiliate, Sunrise Wind LLC, whereby Eversource parent will guaranty Sunrise Wind LLC’s performance of certain obligations, in an amount not to exceed $15.4 million , under the Offshore Wind Renewable Energy Certificate Purchase and Sale Agreement (the Agreement). The Agreement was executed on October 23, 2019, by and between the New York State Energy Research and Development Authority (NYSERDA) and Sunrise Wind LLC. The Company regularly reviews performance risk under this arrangement, and in the event it becomes probable that Eversource parent will be required to perform under the guarantee, the amount of probable payment will be recorded. As of March 31, 2020, the fair value of the guarantee was immaterial.

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 156.0 $ 116.2 $ 113.8 $ 43.0 $ 42.2 $ — $ — Long-Term Debt 14,431.0 15,177.1 3,518.1 3,949.4 3,642.3 3,901.2 951.7 995.8 Rate Reduction Bonds 561.7 596.0 — — — — 561.7 596.0 As of December 31, 2019: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 162.0 $ 116.2 $ 117.8 $ 43.0 $ 44.2 $ — $ — Long-Term Debt 14,098.2 15,170.2 3,518.1 4,058.0 3,342.1 3,659.9 951.6 1,005.7 Rate Reduction Bonds 583.3 625.9 — — — — 583.3 625.9

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 For the Three Months Ended March 31, 2019 Eversource (Millions of Dollars) Qualified Cash Flow Hedging Instruments Unrealized Gains on Marketable Securities Defined Benefit Plans Total Qualified Cash Flow Hedging Instruments Unrealized Gains/(Losses) on Marketable Securities Defined Benefit Plans Total Balance as of January 1st $ (3.0 ) $ 0.7 $ (62.8 ) $ (65.1 ) $ (4.4 ) $ (0.5 ) $ (55.1 ) $ (60.0 ) OCI Before Reclassifications — 0.2 — 0.2 — 0.7 — 0.7 Amounts Reclassified from AOCI 0.2 — 1.6 1.8 0.3 — 1.2 1.5 Net OCI 0.2 0.2 1.6 2.0 0.3 0.7 1.2 2.2 Balance as of March 31st $ (2.8 ) $ 0.9 $ (61.2 ) $ (63.1 ) $ (4.1 ) $ 0.2 $ (53.9 ) $ (57.8 )

COMMON SHARES (Tables)

COMMON SHARES (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 and December 31, 2019 Issued as of Par Value March 31, 2020 December 31, 2019 Eversource $ 5 380,000,000 351,818,402 345,858,402 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, 2020
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, 2020 March 31, 2019 Net Income Attributable to Common Shareholders $ 334.8 $ 308.7 Weighted Average Common Shares Outstanding: Basic 331,102,237 317,624,593 Dilutive Effect of: Share-Based Compensation Awards and Other 747,233 691,489 Equity Forward Sale Agreement 1,087,683 — Total Dilutive Effect 1,834,916 691,489 Diluted 332,937,153 318,316,082 Basic and Diluted EPS $ 1.01 $ 0.97

REVENUES (Tables)

REVENUES (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 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 $ 963.8 $ 238.0 $ — $ 27.8 $ — $ — $ 1,229.6 Commercial 607.0 134.6 — 14.8 — (1.0 ) 755.4 Industrial 79.8 28.3 — 1.1 — (3.2 ) 106.0 Total Retail Tariff Sales Revenues 1,650.6 400.9 — 43.7 — (4.2 ) 2,091.0 Wholesale Transmission Revenues — — 336.3 — 17.3 (283.6 ) 70.0 Wholesale Market Sales Revenues 91.0 13.2 — 0.8 — — 105.0 Other Revenues from Contracts with Customers 19.1 0.9 3.4 1.9 277.3 (276.2 ) 26.4 Amortization/(Reserve) for Revenues Subject to Refund 2.3 0.5 — (0.8 ) — — 2.0 Total Revenues from Contracts with Customers 1,763.0 415.5 339.7 45.6 294.6 (564.0 ) 2,294.4 Alternative Revenue Programs (1) 38.8 32.2 29.8 1.1 — (27.4 ) 74.5 Other Revenues (2) 3.5 0.9 0.2 0.2 — — 4.8 Total Operating Revenues $ 1,805.3 $ 448.6 $ 369.7 $ 46.9 $ 294.6 $ (591.4 ) $ 2,373.7 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 Amortization/(Reserve) for Revenues (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 (1) 2.1 10.4 12.4 0.9 — (11.1 ) 14.7 Other Revenues (2) 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, 2020 For the Three Months Ended March 31, 2019 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Revenues from Contracts with Customers Retail Tariff Sales Residential $ 489.9 $ 331.0 $ 142.9 $ 510.5 $ 371.0 $ 151.8 Commercial 226.4 301.9 79.1 236.7 336.5 79.8 Industrial 34.0 26.8 19.0 34.6 28.8 18.7 Total Retail Tariff Sales Revenues 750.3 659.7 241.0 781.8 736.3 250.3 Wholesale Transmission Revenues 151.8 134.8 49.7 154.8 122.6 47.5 Wholesale Market Sales Revenues 64.7 14.4 11.9 13.7 24.4 13.4 Other Revenues from Contracts with Customers 8.8 10.7 3.7 8.9 4.0 3.6 Amortization/(Reserve) for Revenues — — 2.3 — — (3.1 ) Total Revenues from Contracts with Customers 975.6 819.6 308.6 959.2 887.3 311.7 Alternative Revenue Programs (1) 44.6 19.3 4.7 5.7 7.3 1.5 Other Revenues (2) 1.7 1.4 0.6 1.0 1.5 0.3 Eliminations (122.2 ) (106.5 ) (37.5 ) (116.7 ) (98.5 ) (37.1 ) Total Operating Revenues $ 899.7 $ 733.8 $ 276.4 $ 849.2 $ 797.6 $ 276.4 (1) CL&P, NSTAR Electric, Yankee Gas, NSTAR Gas and the Connecticut water distribution business each have a revenue decoupling mechanism approved by a regulatory commission. The revenue decoupling mechanisms mitigate the im pact of lower demand and resulting lost sales revenues by allowing for a true-up to occur as part of each company’s annual decoupling filing. These revenue decoupling mechanisms qualify as alternative revenue programs in accordance with accounting guidance for rate-regulated operations. The increase in revenues from Alternative Revenue Programs for the three months ended March 31, 2020, as compared to the three months ended March 31, 2019, was primarily the result of a higher decoupling deferral adjustment driven by lower distribution sales volumes in the first quarter of 2020. The decoupling deferral adjustment to revenues is recorded as a regulatory tracker mechanism within Regulatory Assets on the balance sheets. (2) Other Revenues include certain fees charged to customers that are not considered revenue from contracts with customers. Other revenues also includes lease revenues under lessor accounting guidance of $1.1 million (including $0.2 million at CL&P, and $0.7 million at NSTAR Electric) and $1.0 million (including $0.2 million at CL&P, and $0.6 million at NSTAR Electric) for the three months ended March 31, 2020 and March 31, 2019 , respectively.

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 Eversource (Millions of Dollars) Electric Distribution Natural Gas Distribution Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 1,805.3 $ 448.6 $ 369.7 $ 46.9 $ 294.6 $ (591.4 ) $ 2,373.7 Depreciation and Amortization (167.3 ) (19.1 ) (67.5 ) (11.4 ) (21.3 ) 0.6 (286.0 ) Other Operating Expenses (1,439.6 ) (311.6 ) (106.8 ) (25.0 ) (257.0 ) 591.4 (1,548.6 ) Operating Income $ 198.4 $ 117.9 $ 195.4 $ 10.5 $ 16.3 $ 0.6 $ 539.1 Interest Expense $ (53.1 ) $ (11.4 ) $ (30.6 ) $ (8.7 ) $ (42.7 ) $ 11.8 $ (134.7 ) Other Income, Net 12.5 1.4 5.2 0.1 468.1 (463.2 ) 24.1 Net Income Attributable to Common Shareholders 130.1 84.4 126.8 2.1 442.2 (450.8 ) 334.8 Cash Flows Used for Investments in Plant 315.8 99.1 232.8 18.5 59.3 — 725.5 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 (1) 279.3 87.4 184.8 20.7 55.9 — 628.1 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, 2020 $ 23,135.9 $ 4,430.4 $ 11,137.5 $ 2,368.7 $ 20,860.8 $ (20,284.3 ) $ 41,649.0 As of December 31, 2019 22,541.9 4,345.5 10,904.0 2,351.7 20,469.6 (19,488.8 ) 41,123.9 (1) See Note 1A, "Summary of Significant Accounting Policies - Basis of Presentation," for information regarding the correction of cash investments in plant reported in 2019.

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands, customer in Millions	Feb. 26, 2020USD ($)	Mar. 31, 2020USD ($)customerutility	Mar. 31, 2019USD ($)	Jan. 01, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Summary of Accounting Policies [Line Items]
Number of electric, natural gas and water customers | customer		4,000,000
Decrease to operating cash flows inflows in accounts payable		$ (127,366)	$ (60,121)
Decrease to investing cash outflows in investments in property, plant and equipment		(725,520)	(628,129)
Allowance for uncollectible accounts for late fees and other receivable amounts		262,100			$ 224,800
Stockholders' equity		13,209,956	11,637,434		12,629,994	$ 11,486,817
Adoption of new accounting standard				$ (1,514)
Energy efficiency funds collected from customers to be remitted to the State of Connecticut		10,700
Columbia Gas of Massachusetts (CMA)
Summary of Accounting Policies [Line Items]
Purchase price	$ 1,100,000
Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity		4,322,825	4,092,895		4,177,048	3,953,974
Adoption of new accounting standard				(1,514)
NSTAR Electric
Summary of Accounting Policies [Line Items]
Decrease to operating cash flows inflows in accounts payable		(53,462)	(18,109)
Decrease to investing cash outflows in investments in property, plant and equipment		(247,549)	(208,540)
Allowance for uncollectible accounts for late fees and other receivable amounts		71,100			75,400
Stockholders' equity		4,063,190	3,783,196		4,159,884	3,730,155
Adoption of new accounting standard				(161)
NSTAR Electric | Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity		2,249,526	2,131,015		2,346,287	2,098,091
Adoption of new accounting standard				(161)
CL&P
Summary of Accounting Policies [Line Items]
Decrease to operating cash flows inflows in accounts payable		(27,298)	75,373
Decrease to investing cash outflows in investments in property, plant and equipment		(212,374)	(189,423)
Allowance for uncollectible accounts for late fees and other receivable amounts		130,900			97,300
Stockholders' equity		$ 4,434,772	4,209,415		4,387,825	4,199,317
Adoption of new accounting standard				(900)
Period of accounts receivable recoverable under financial or medical duress		180 days
CL&P | Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity		$ 1,838,340	1,737,980		1,791,392	1,727,899
Adoption of new accounting standard				(900)
PSNH
Summary of Accounting Policies [Line Items]
Decrease to operating cash flows inflows in accounts payable		(18,064)	11,762
Decrease to investing cash outflows in investments in property, plant and equipment		(88,694)	(64,361)
Allowance for uncollectible accounts for late fees and other receivable amounts		11,200			10,500
Stockholders' equity		1,409,012	1,316,629		1,391,733	1,302,541
Adoption of new accounting standard				(300)
PSNH | Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity		$ 507,307	641,039		490,306	$ 627,258
Adoption of new accounting standard				(300)
Yankee Gas
Summary of Accounting Policies [Line Items]
Period of accounts receivable recoverable under financial or medical duress		90 days
Restatement Adjustment
Summary of Accounting Policies [Line Items]
Decrease to operating cash flows inflows in accounts payable			46,600
Decrease to investing cash outflows in investments in property, plant and equipment			46,600
Restatement Adjustment | PSNH
Summary of Accounting Policies [Line Items]
Decrease to operating cash flows inflows in accounts payable			46,600
Decrease to investing cash outflows in investments in property, plant and equipment			$ 46,600
Connecticut, Massachusetts and New Hampshire
Summary of Accounting Policies [Line Items]
Number of regulated utilities | utility		8
Revision of Prior Period, Adjustment
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					23,800
Revision of Prior Period, Adjustment | NSTAR Electric
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					(1,300)
Revision of Prior Period, Adjustment | CL&P
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					22,200
Revision of Prior Period, Adjustment | PSNH
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					300
Adoption Adjustment | Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity				(1,500)
Adoption Adjustment | NSTAR Electric | Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity				(200)
Adoption Adjustment | CL&P | Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity				(900)
Adoption Adjustment | PSNH
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts				300
Adoption Adjustment | PSNH | Retained Earnings
Summary of Accounting Policies [Line Items]
Stockholders' equity				(300)
Retail (Non-Hardship), Wholesale, and Other Receivables
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts		$ 89,900			81,500
Retail (Non-Hardship), Wholesale, and Other Receivables | NSTAR Electric
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts		32,600			31,500
Retail (Non-Hardship), Wholesale, and Other Receivables | CL&P
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts		$ 20,200			17,200
Retail (Non-Hardship), Wholesale, and Other Receivables | Revision of Prior Period, Adjustment
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					2,200
Retail (Non-Hardship), Wholesale, and Other Receivables | Revision of Prior Period, Adjustment | NSTAR Electric
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					300
Retail (Non-Hardship), Wholesale, and Other Receivables | Revision of Prior Period, Adjustment | CL&P
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					900
Retail (Non-Hardship), Wholesale, and Other Receivables | Adoption Adjustment
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts				1,600
Retail (Non-Hardship), Wholesale, and Other Receivables | Adoption Adjustment | NSTAR Electric
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts				200
Retail (Non-Hardship), Wholesale, and Other Receivables | Adoption Adjustment | CL&P
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts				$ 900
Hardship Accounts and Other Low-Income Assistance Programs | Revision of Prior Period, Adjustment
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					22,200
Hardship Accounts and Other Low-Income Assistance Programs | Revision of Prior Period, Adjustment | NSTAR Electric
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					(1,500)
Hardship Accounts and Other Low-Income Assistance Programs | Revision of Prior Period, Adjustment | CL&P
Summary of Accounting Policies [Line Items]
Allowance for uncollectible accounts for late fees and other receivable amounts					$ 21,300

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for Uncollectible Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 224,800
Uncollectible Expense	11,353	$ 18,565
Uncollectible Costs Deferred	20,300
Write-Offs	(21,500)
Recoveries Collected	3,300
Ending Balance	262,100
CL&P
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	97,300
Uncollectible Expense	3,230	4,116
Uncollectible Costs Deferred	14,700
Write-Offs	(7,300)
Recoveries Collected	800
Ending Balance	130,900
NSTAR Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	75,400
Uncollectible Expense	3,704	5,953
Uncollectible Costs Deferred	0
Write-Offs	(8,400)
Recoveries Collected	1,700
Ending Balance	71,100
PSNH
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	10,500
Uncollectible Expense	666	$ 1,725
Uncollectible Costs Deferred	1,300
Write-Offs	(1,700)
Recoveries Collected	100
Ending Balance	11,200
Revision of Prior Period, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	23,800
Revision of Prior Period, Adjustment | CL&P
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	22,200
Revision of Prior Period, Adjustment | NSTAR Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	(1,300)
Revision of Prior Period, Adjustment | PSNH
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	300
Hardship Accounts
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	143,300
Uncollectible Expense	0
Uncollectible Costs Deferred	11,800
Write-Offs	(4,700)
Recoveries Collected	200
Ending Balance	172,200
Hardship Accounts | CL&P
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	80,100
Uncollectible Expense	0
Uncollectible Costs Deferred	12,900
Write-Offs	(3,800)
Recoveries Collected	200
Ending Balance	110,700
Hardship Accounts | NSTAR Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	43,900
Uncollectible Expense	0
Uncollectible Costs Deferred	(3,400)
Write-Offs	(400)
Recoveries Collected	0
Ending Balance	38,500
Hardship Accounts | Revision of Prior Period, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	21,600
Hardship Accounts | Revision of Prior Period, Adjustment | CL&P
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	21,300
Hardship Accounts | Revision of Prior Period, Adjustment | NSTAR Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	(1,600)
Retail (Non-Hardship), Wholesale, and Other Receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	81,500
Uncollectible Expense	11,400
Uncollectible Costs Deferred	8,500
Write-Offs	(16,800)
Recoveries Collected	3,100
Ending Balance	89,900
Retail (Non-Hardship), Wholesale, and Other Receivables | CL&P
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	17,200
Uncollectible Expense	3,200
Uncollectible Costs Deferred	1,800
Write-Offs	(3,500)
Recoveries Collected	600
Ending Balance	20,200
Retail (Non-Hardship), Wholesale, and Other Receivables | NSTAR Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	31,500
Uncollectible Expense	3,700
Uncollectible Costs Deferred	3,400
Write-Offs	(8,000)
Recoveries Collected	1,700
Ending Balance	32,600
Retail (Non-Hardship), Wholesale, and Other Receivables | Revision of Prior Period, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	2,200
Retail (Non-Hardship), Wholesale, and Other Receivables | Revision of Prior Period, Adjustment | CL&P
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	900
Retail (Non-Hardship), Wholesale, and Other Receivables | Revision of Prior Period, Adjustment | NSTAR Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 300

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Components of Other Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Summary of Accounting Policies [Line Items]
Other income, net	$ 24,104	$ 30,985
Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other income, net	12,700	7,400
AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	10,600	10,900
Equity in Earnings of Unconsolidated Affiliates
Summary of Accounting Policies [Line Items]
Other income, net	4,000	5,000
Investment Income/(Loss)
Summary of Accounting Policies [Line Items]
Other income, net	(4,300)	1,200
Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	700	6,500
Other
Summary of Accounting Policies [Line Items]
Other income, net	400	0
CL&P
Summary of Accounting Policies [Line Items]
Other income, net	1,898	3,880
CL&P | Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other income, net	1,100	(600)
CL&P | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	3,900	2,600
CL&P | Equity in Earnings of Unconsolidated Affiliates
Summary of Accounting Policies [Line Items]
Other income, net	0	0
CL&P | Investment Income/(Loss)
Summary of Accounting Policies [Line Items]
Other income, net	(3,400)	1,700
CL&P | Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	300	400
CL&P | Other
Summary of Accounting Policies [Line Items]
Other income, net	0	(200)
NSTAR Electric
Summary of Accounting Policies [Line Items]
Other income, net	12,238	11,086
NSTAR Electric | Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other income, net	7,900	7,000
NSTAR Electric | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	5,000	4,000
NSTAR Electric | Equity in Earnings of Unconsolidated Affiliates
Summary of Accounting Policies [Line Items]
Other income, net	100	200
NSTAR Electric | Investment Income/(Loss)
Summary of Accounting Policies [Line Items]
Other income, net	(1,300)	(300)
NSTAR Electric | Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	100	200
NSTAR Electric | Other
Summary of Accounting Policies [Line Items]
Other income, net	400	0
PSNH
Summary of Accounting Policies [Line Items]
Other income, net	3,190	7,022
PSNH | Pension, SERP and PBOP Non-Service Income Components
Summary of Accounting Policies [Line Items]
Other income, net	1,900	500
PSNH | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	1,500	200
PSNH | Equity in Earnings of Unconsolidated Affiliates
Summary of Accounting Policies [Line Items]
Other income, net	0	0
PSNH | Investment Income/(Loss)
Summary of Accounting Policies [Line Items]
Other income, net	(500)	400
PSNH | Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	300	5,900
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, 2020	Mar. 31, 2019
Schedule of Gross Tax Receipts [Line Items]
Gross receipts taxes	$ 43.1	$ 45
CL&P
Schedule of Gross Tax Receipts [Line Items]
Gross receipts taxes	$ 35.5	$ 36.2

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Non-cash Investing Activities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	$ 273.7	$ 336.3
CL&P
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	85	121.9
NSTAR Electric
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	70.2	83.2
PSNH
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	$ 37.9	$ 30.4

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, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	$ 47,425	$ 15,432
Cash and Restricted Cash reported on the Statements of Cash Flows	133,689	117,063	$ 108,372	$ 209,324
Special Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	39,000	52,500
Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	44,100	46,000
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	3,785	0
Cash and Restricted Cash reported on the Statements of Cash Flows	8,767	4,971	11,404	91,613
CL&P | Special Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	4,700	4,600
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	2,844	52
Cash and Restricted Cash reported on the Statements of Cash Flows	9,129	6,312	14,905	14,659
NSTAR Electric | Special Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	6,200	6,200
NSTAR Electric | Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	100	0
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	19	413
Cash and Restricted Cash reported on the Statements of Cash Flows	20,390	36,688	$ 28,796	$ 52,723
PSNH | Special Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	16,600	32,500
PSNH | Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	600	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, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 5,563,400	$ 5,514,700
Less: Current Portion	785,125	651,112
Total Long-Term Regulatory Assets	4,778,321	4,863,639
Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	2,334,300	2,382,900
Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	727,200	725,800
Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	554,500	565,300
Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	497,600	540,600
Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	551,500	411,500
Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	335,200	334,500
Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	327,300	331,500
Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	99,300	97,200
Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	136,500	125,400
CL&P
Regulatory Assets [Line Items]
Total Regulatory Assets	1,819,600	1,735,900
Less: Current Portion	290,630	178,607
Total Long-Term Regulatory Assets	1,529,003	1,557,261
CL&P | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	528,300	539,000
CL&P | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	458,900	458,800
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	251,600	274,600
CL&P | Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	191,000	78,300
CL&P | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	333,800	329,200
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	31,200	30,800
CL&P | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	24,800	25,200
NSTAR Electric
Regulatory Assets [Line Items]
Total Regulatory Assets	1,529,300	1,535,600
Less: Current Portion	304,007	285,591
Total Long-Term Regulatory Assets	1,225,314	1,250,029
NSTAR Electric | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	616,300	629,800
NSTAR Electric | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	108,500	108,000
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	183,000	200,600
NSTAR Electric | Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	227,400	207,100
NSTAR Electric | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric | Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	281,000	284,600
NSTAR Electric | Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	51,500	50,300
NSTAR Electric | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	61,600	55,200
PSNH
Regulatory Assets [Line Items]
Total Regulatory Assets	946,300	945,800
Less: Current Portion	102,438	84,053
Total Long-Term Regulatory Assets	843,904	861,672
PSNH | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	213,900	218,200
PSNH | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	12,800	12,800
PSNH | Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	554,500	565,300
PSNH | Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	63,000	65,400
PSNH | Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	84,600	65,800
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	3,700	3,600
PSNH | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 13,800	$ 14,700

REGULATORY ACCOUNTING - Narrati

REGULATORY ACCOUNTING - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	$ 171.3	$ 146
CL&P
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	82.6	51.8
PSNH
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	16.9	18
NSTAR Electric
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved	$ 50.3	$ 55.7

REGULATORY ACCOUNTING - Compo_2

REGULATORY ACCOUNTING - Components of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 4,108,100	$ 4,019,200
Less: Current Portion	439,859	361,152
Total Long-Term Regulatory Liabilities	3,668,158	3,658,042
EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	2,831,200	2,844,600
Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	579,300	559,800
Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	80,100	84,500
Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	412,500	325,100
AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	74,400	73,200
Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	130,600	132,000
CL&P
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,299,000	1,247,800
Less: Current Portion	119,283	82,763
Total Long-Term Regulatory Liabilities	1,179,663	1,164,991
CL&P | EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,019,800	1,022,800
CL&P | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	77,400	64,600
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	121,700	94,800
CL&P | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	45,700	46,000
CL&P | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	34,400	19,600
NSTAR Electric
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,735,600	1,725,800
Less: Current Portion	219,872	209,180
Total Long-Term Regulatory Liabilities	1,515,732	1,516,585
NSTAR Electric | EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,063,900	1,071,200
NSTAR Electric | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	337,200	330,600
NSTAR Electric | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	68,600	72,200
NSTAR Electric | Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	189,800	165,600
NSTAR Electric | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	28,700	27,200
NSTAR Electric | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	47,400	59,000
PSNH
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	481,000	479,200
Less: Current Portion	69,042	65,766
Total Long-Term Regulatory Liabilities	411,959	413,381
PSNH | EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	391,400	392,800
PSNH | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	14,800	16,300
PSNH | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH | Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	64,100	57,000
PSNH | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 10,700	$ 13,100

PROPERTY, PLANT AND EQUIPMENT_3

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	$ 16,117,400	$ 15,880,000
Distribution - Natural Gas	3,984,200	3,931,100
Transmission - Electric	11,059,400	10,958,400
Distribution - Water	1,730,200	1,726,500
Solar	200,500	200,200
Utility	33,091,700	32,696,200
Other	1,073,200	1,025,600
Property, Plant and Equipment, Gross	34,164,900	33,721,800
Less: Accumulated Depreciation
Utility	(7,572,400)	(7,483,500)
Other	(408,000)	(387,400)
Total Accumulated Depreciation	(7,980,400)	(7,870,900)
Property, Plant and Equipment, Net	26,184,500	25,850,900
Construction Work in Progress	1,856,900	1,734,600
Total Property, Plant and Equipment, Net	28,041,356	27,585,470
CL&P
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	6,607,800	6,485,500
Transmission - Electric	5,094,100	5,043,000
Solar	0	0
Property, Plant and Equipment, Gross	11,701,900	11,528,500
Less: Accumulated Depreciation
Total Accumulated Depreciation	(2,413,600)	(2,385,700)
Property, Plant and Equipment, Net	9,288,300	9,142,800
Construction Work in Progress	472,600	483,000
Total Property, Plant and Equipment, Net	9,760,890	9,625,765
NSTAR Electric
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	7,250,800	7,163,700
Transmission - Electric	4,444,700	4,411,900
Solar	200,500	200,200
Property, Plant and Equipment, Gross	11,896,000	11,775,800
Less: Accumulated Depreciation
Total Accumulated Depreciation	(2,925,200)	(2,895,300)
Property, Plant and Equipment, Net	8,970,800	8,880,500
Construction Work in Progress	643,800	592,300
Total Property, Plant and Equipment, Net	9,614,555	9,472,770
PSNH
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	2,299,100	2,271,100
Transmission - Electric	1,515,800	1,498,700
Solar	0	0
Property, Plant and Equipment, Gross	3,814,900	3,769,800
Less: Accumulated Depreciation
Total Accumulated Depreciation	(810,100)	(799,900)
Property, Plant and Equipment, Net	3,004,800	2,969,900
Construction Work in Progress	182,500	159,600
Total Property, Plant and Equipment, Net	$ 3,187,282	$ 3,129,506

DERIVATIVE INSTRUMENTS - Gross

DERIVATIVE INSTRUMENTS - Gross Fair Values and Net Amounts of Contracts (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
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	$ 12.8	$ 12.2
Netting	(0.4)	(0.4)
Net Amount Recorded as a Derivative	12.4	11.8
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	68.2	67.5
Netting	(2.1)	(2.1)
Net Amount Recorded as a Derivative	66.1	65.4
Current Derivative Liabilities | CL&P | Level 3
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(69.6)	(67.8)
Netting	0	0
Net Amount Recorded as a Derivative	(69.6)	(67.8)
Current Derivative Liabilities | Other | Level 2
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(1.4)	(5.2)
Netting	0.3	0
Net Amount Recorded as a Derivative	(1.1)	(5.2)
Long-Term Derivative Liabilities | CL&P | Level 3
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(342.7)	(338.6)
Netting	0	0
Net Amount Recorded as a Derivative	(342.7)	(338.6)
Long-Term Derivative Liabilities | Other | Level 2
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(0.3)	(0.1)
Netting	0	0
Net Amount Recorded as a Derivative	$ (0.3)	$ (0.1)

DERIVATIVE INSTRUMENTS - Narrat

DERIVATIVE INSTRUMENTS - Narrative (Details) MWh in Millions, MMBTU in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020USD ($)MMBTUMWhMW	Mar. 31, 2019USD ($)	Dec. 31, 2019MMBTUMW
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	676		676
Amount of natural gas to be purchased under futures contracts | MMBTU	3.5		9.6
Gains (losses) on deferred as regulatory costs | $	$ (18)	$ (5.2)
Level 3 | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts	1.50%
Level 3 | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts	13.00%
Level 3 | Weighted Average
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts	11.90%
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 Unobservable Inputs Used (Details) - CL&P - Level 3 - $ / KWmo	Mar. 31, 2020	Dec. 31, 2019
Capacity Prices | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	4.30	3.01
Capacity Prices | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	5.82	7.34
Capacity Prices | Weighted Average
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	4.81
Forward Reserve Prices | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	0.80	0.80
Forward Reserve Prices | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	1.90	1.90
Forward Reserve Prices | Weighted Average
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	1.35

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, 2020	Mar. 31, 2019
Derivatives, Net [Rollforward]
Fair Value as of Beginning of Period	$ (329.2)	$ (356.5)
Net Realized/Unrealized Losses Included in Regulatory Assets	(16.4)	(5.3)
Settlements	11.8	8.7
Fair Value as of End of Period	$ (333.8)	$ (353.1)

MARKETABLE SECURITIES - Narrati

MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	$ 34.8		$ 45.7
Unrealized loss recorded in other income	9.1
Unrealized gains recorded in other income		$ 1
CYAPC and YAEC
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	162		182.8
Marketable securities held in nuclear decommissioning trust	$ 198.7		$ 198.1

MARKETABLE SECURITIES - Summary

MARKETABLE SECURITIES - Summary of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Amortized Cost	$ 224.2	$ 228.4
Pre-Tax Unrealized Gains	10.9	5.8
Pre-Tax Unrealized Losses	(0.6)	(0.1)
Fair Value	$ 234.5	$ 234.1

MARKETABLE SECURITIES - Contrac

MARKETABLE SECURITIES - Contractual Maturities of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Amortized Cost
Less than one year	$ 56.5
One to five years	40.1
Six to ten years	38.6
Greater than ten years	89
Amortized Cost	224.2	$ 228.4
Fair Value
Less than one year	56.6
One to five years	41.7
Six to ten years	41.4
Greater than ten years	94.8
Fair Value	$ 234.5	$ 234.1

MARKETABLE SECURITIES - Marketa

MARKETABLE SECURITIES - Marketable Securities Recorded at Fair Value on a Recurring Basis by Level (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 431.3	$ 462.6
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	240.9	274.5
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	190.4	188.1
Mutual Funds and Equities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	196.8	228.5
Money Market Funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	44.1	46
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	100.9	96.8
Corporate Debt Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	45.9	44
Asset-Backed Debt Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	13.7	12.9
Municipal Bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	22.2	26.7
Other Fixed Income Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 7.7	$ 7.7

SHORT-TERM AND LONG-TERM DEBT -

SHORT-TERM AND LONG-TERM DEBT - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 27, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Issuance of Long-Term Debt	$ 750,000,000	$ 0
CL&P
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	219,000,000			$ 63,800,000
PSNH
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	84,700,000			27,000,000
NSTAR Electric
Line of Credit Facility [Line Items]
Issuance of Long-Term Debt	400,000,000	$ 0
Notes payable to Eversource parent	38,400,000			30,300,000
NSTAR Gas Company [Member]
Line of Credit Facility [Line Items]
Current portion of long-term debt	25,000,000
Amount of long-term debt approved for issuance			$ 270,000,000
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
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
Issuance of Long-Term Debt	165,000,000
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, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Borrowings outstanding	$ 738.4	$ 1,224.9
Available borrowing capacity	$ 711.6	$ 225.1
Weighted-average interest rate	3.38%	1.98%
NSTAR Electric
Debt Instrument [Line Items]
Borrowings outstanding	$ 88	$ 10.5
Available borrowing capacity	$ 562	$ 639.5
Weighted-average interest rate	1.25%	1.63%

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	1 Months Ended				3 Months Ended
	May 31, 2020	Apr. 30, 2020	Mar. 31, 2020	Jan. 31, 2020	Mar. 31, 2020	Mar. 31, 2019
Debt Instrument [Line Items]
Repayments					$ (220,253)	$ (250,215)
Senior Notes | Eversource Parent 3.45% Series P Senior Notes | Eversource Parent
Debt Instrument [Line Items]
Issuances				$ 350,000
Interest rate, stated percentage				3.45%
NSTAR Electric
Debt Instrument [Line Items]
Repayments					$ (95,000)	$ 0
NSTAR Electric | Senior Notes | 3.95% 2020 Debentures
Debt Instrument [Line Items]
Issuances			$ 400,000
Interest rate, stated percentage			3.95%		3.95%
NSTAR Electric | Senior Notes | 5.10% Series E Senior Notes
Debt Instrument [Line Items]
Repayments			$ (95,000)
Interest rate, stated percentage			5.10%		5.10%
NSTAR Gas | Senior Notes | NSTAR Gas 4.46% Series N First Mortgage Bonds
Debt Instrument [Line Items]
Repayments				$ (125,000)
Interest rate, stated percentage				4.46%
NSTAR Gas | Senior Notes | NSTAR Gas 2.33% Series R First Mortgage Bonds | Subsequent Event
Debt Instrument [Line Items]
Issuances	$ 75,000
Interest rate, stated percentage	2.33%
NSTAR Gas | Senior Notes | NSTAR Gas 3.15% Series S First Mortgage Bonds | Subsequent Event
Debt Instrument [Line Items]
Issuances	$ 115,000
Interest rate, stated percentage	3.15%
Yankee Gas | Senior Notes | Yankee Gas 4.87% Series K First Mortgage Bonds | Subsequent Event
Debt Instrument [Line Items]
Repayments		$ (50,000)
Interest rate, stated percentage		4.87%

RATE REDUCTION BONDS AND VARI_3

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Narrative (Details) - PSNH - Rate Reduction Bonds $ in Millions	May 08, 2018USD ($)
Debt Instrument [Line Items]
Amount of securitized rate reduction bonds issued	$ 635.7
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, 2020	Dec. 31, 2019
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	$ 5,563,400	$ 5,514,700
Regulatory Liabilities	3,668,158	3,658,042
Accrued Interest (included in Other Current Liabilities)	611,706	676,685
Rate Reduction Bonds - Current Portion	43,210	43,210
Rate Reduction Bonds - Long-Term Portion	518,517	540,122
Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	554,500	565,300
Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	136,500	125,400
Special Deposits
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	39,000	52,500
Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	3,200	3,200
PSNH
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	946,300	945,800
Regulatory Liabilities	411,959	413,381
Accrued Interest (included in Other Current Liabilities)	39,636	32,736
Rate Reduction Bonds - Current Portion	43,210	43,210
Rate Reduction Bonds - Long-Term Portion	518,517	540,122
PSNH | VIE
Condensed Balance Sheet Statements, Captions [Line Items]
Rate Reduction Bonds - Current Portion	43,200	43,200
Rate Reduction Bonds - Long-Term Portion	518,500	540,100
PSNH | Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	554,500	565,300
PSNH | Securitized Stranded Costs | VIE
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	554,500	565,300
PSNH | Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	13,800	14,700
PSNH | Other Regulatory Assets | VIE
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Liabilities	6,000	5,600
Accrued Interest (included in Other Current Liabilities)	3,300	8,600
PSNH | Special Deposits
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	16,600	32,500
PSNH | Special Deposits | VIE
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	16,600	32,500
PSNH | Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	3,200	3,200
PSNH | Other Long-Term Assets | VIE
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, 2020	Mar. 31, 2019
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 134,715	$ 131,734
PSNH
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	20,110	13,667
Interest Expense on RRB Principal (included in Interest Expense)	14,479	14,367
PSNH | VIE | Rate Reduction Bonds
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	10,800	10,600
Interest Expense on RRB Principal (included in Interest Expense)	$ 5,000	$ 5,400

PENSION BENEFITS AND POSTRETI_3

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION - Components of Net Periodic Benefit Expense/(Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	$ 19.6	$ 19.3
Interest Cost	44.3	54.2
Expected Return on Pension Plan Assets	(100.3)	(92.3)
Actuarial Loss	49.3	35.8
Prior Service Cost/(Credit)	0.3	1.1
Total Net Periodic Benefit Expense/(Income)	13.2	18.1
PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	2.6	2.1
Interest Cost	6.1	8.1
Expected Return on Pension Plan Assets	(18.1)	(16.6)
Actuarial Loss	2.1	2.5
Prior Service Cost/(Credit)	(5.4)	(5.8)
Total Net Periodic Benefit Expense/(Income)	(12.7)	(9.7)
CL&P | Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	5.7	4.8
Interest Cost	9.5	11.5
Expected Return on Pension Plan Assets	(20)	(18.8)
Actuarial Loss	10	8.1
Prior Service Cost/(Credit)	0	0
Total Net Periodic Benefit Expense/(Income)	5.2	5.6
Intercompany Allocations	1.9	7.8
CL&P | PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.5	0.4
Interest Cost	1.2	1.5
Expected Return on Pension Plan Assets	(2.4)	(2.3)
Actuarial Loss	0.4	0.4
Prior Service Cost/(Credit)	0.2	0.3
Total Net Periodic Benefit Expense/(Income)	(0.1)	0.3
Intercompany Allocations	(0.4)	(0.1)
NSTAR Electric | Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	3.8	3.9
Interest Cost	9.6	11.9
Expected Return on Pension Plan Assets	(25.8)	(24.4)
Actuarial Loss	13.3	9.4
Prior Service Cost/(Credit)	0.1	0.1
Total Net Periodic Benefit Expense/(Income)	1	0.9
Intercompany Allocations	1.9	3
NSTAR Electric | PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.6	0.4
Interest Cost	1.7	2.3
Expected Return on Pension Plan Assets	(8.5)	(7.5)
Actuarial Loss	0.7	0.9
Prior Service Cost/(Credit)	(4.2)	(4.2)
Total Net Periodic Benefit Expense/(Income)	(9.7)	(8.1)
Intercompany Allocations	(0.4)	(0.2)
PSNH | Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	2.2	2.6
Interest Cost	4.9	6.2
Expected Return on Pension Plan Assets	(11.3)	(10.3)
Actuarial Loss	4.1	3.5
Prior Service Cost/(Credit)	0	0
Total Net Periodic Benefit Expense/(Income)	(0.1)	2
Intercompany Allocations	0.6	2.4
PSNH | PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.2	0.2
Interest Cost	0.6	0.9
Expected Return on Pension Plan Assets	(1.4)	(1.3)
Actuarial Loss	0.1	0.2
Prior Service Cost/(Credit)	0.1	0.1
Total Net Periodic Benefit Expense/(Income)	(0.4)	0.1
Intercompany Allocations	$ (0.2)	$ (0.1)

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Environmental Sites and Related Reserves (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020USD ($)site	Dec. 31, 2019USD ($)site
Site Contingency [Line Items]
Number of Sites | site	55	57
Reserve | $	$ 79.1	$ 81
CL&P
Site Contingency [Line Items]
Number of Sites | site	15	15
Reserve | $	$ 11.8	$ 11.4
NSTAR Electric
Site Contingency [Line Items]
Number of Sites | site	13	15
Reserve | $	$ 6.2	$ 8
PSNH
Site Contingency [Line Items]
Number of Sites | site	9	9
Reserve | $	$ 7.4	$ 7.5

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Environmental Matters (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Site Contingency [Line Items]
Reserve balance	$ 79.1	$ 81
MGP Sites
Site Contingency [Line Items]
Reserve balance	$ 67.4	$ 67.9

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Guarantees and Indemnifications (Details) - USD ($) $ in Millions	Mar. 31, 2020	Oct. 25, 2019
Sunrise Wind, LLC
Guarantor Obligations [Line Items]
Maximum exposure (up to)		$ 15.4
Ownership interest		50.00%
Surety Bond
Guarantor Obligations [Line Items]
Maximum exposure (up to)	$ 30
Lease Payments for Real Estate
Guarantor Obligations [Line Items]
Maximum exposure (up to)	6.1
Real Estate Purchase
Guarantor Obligations [Line Items]
Maximum exposure (up to)	2.5
Sunrise Wind, LLC - Offshore Wind
Guarantor Obligations [Line Items]
Maximum exposure (up to)	$ 2.2

COMMITMENTS AND CONTINGENCIES_4

COMMITMENTS AND CONTINGENCIES - Spent Nuclear Fuel Obligations - Yankee Companies (Details) - USD ($) $ in Millions	Jun. 12, 2019	Feb. 21, 2019	May 22, 2017	Dec. 31, 2019	Jul. 31, 2019
Loss Contingencies [Line Items]
Damages awarded	$ 0.5
Remaining damages sought		$ 1
Damages paid					$ 0.5
DOE settlement payment				$ 29
YAEC
Loss Contingencies [Line Items]
Damages awarded				2.8
Total amount of damages awarded				5.4
MYAPC
Loss Contingencies [Line Items]
Damages awarded				5
Total amount of damages awarded				$ 21
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_5

COMMITMENTS AND CONTINGENCIES - FERC ROE Complaints (Details) - USD ($) $ in Millions	Apr. 29, 2016	Oct. 16, 2014	Mar. 31, 2020	Mar. 31, 2019	Oct. 15, 2014	Dec. 31, 2019
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified			10.41%
Percentage of incentive cap on total ROE			13.08%
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			$ 39.1
FERC ROE Second Complaint | CL&P
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			21.4			21.4
FERC ROE Second Complaint | NSTAR Electric
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			14.6			14.6
FERC ROE Second Complaint | PSNH
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			$ 3.1			$ 3.1

COMMITMENTS AND CONTINGENCIES_6

COMMITMENTS AND CONTINGENCIES - Eversource and NSTAR Electric Boston Harbor Civil Action (Details)	Jul. 15, 2016kV
Commitments and Contingencies Disclosure [Abstract]
Amount of capacity required for installation of distribution cable (in kV)	115

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
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	518,517	540,122
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	14,431,000	14,098,200
Rate Reduction Bonds	561,700	583,300
Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	156,000	162,000
Long-Term Debt	15,177,100	15,170,200
Rate Reduction Bonds	596,000	625,900
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	3,518,100	3,518,100
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	113,800	117,800
Long-Term Debt	3,949,400	4,058,000
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	3,642,300	3,342,100
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	42,200	44,200
Long-Term Debt	3,901,200	3,659,900
Rate Reduction Bonds	0	0
PSNH
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate Reduction Bonds	518,517	540,122
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	951,700	951,600
Rate Reduction Bonds	561,700	583,300
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	995,800	1,005,700
Rate Reduction Bonds	$ 596,000	$ 625,900

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications	$ 200	$ 700
Amounts Reclassified from AOCI	1,800	1,500
Other Comprehensive Income (Loss), Net of Tax	1,948	2,196
Total
AOCI Attributable to Parent [Roll Forward]
Balance	(65,100)	(60,000)
Other Comprehensive Income (Loss), Net of Tax	1,948	2,196
Balance	(63,100)	(57,800)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Balance	(3,000)	(4,400)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	200	300
Other Comprehensive Income (Loss), Net of Tax	200	300
Balance	(2,800)	(4,100)
Unrealized Gains on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Balance	700	(500)
OCI Before Reclassifications	200	700
Amounts Reclassified from AOCI	0	0
Other Comprehensive Income (Loss), Net of Tax	200	700
Balance	900	200
Defined Benefit Plans
AOCI Attributable to Parent [Roll Forward]
Balance	(62,800)	(55,100)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	1,600	1,200
Other Comprehensive Income (Loss), Net of Tax	1,600	1,200
Balance	$ (61,200)	$ (53,900)

COMMON SHARES - Common Shares A

COMMON SHARES - Common Shares Authorized and Issued (Details) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Per value (in dollars per share)	$ 5
Authorized (in shares)	380,000,000	380,000,000
Issued (in shares)	351,818,402	345,858,402
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) - USD ($) $ / shares in Units, $ in Thousands	Mar. 26, 2020	Mar. 23, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Equity offering (in shares)			6,000,000	5,980,000
Common shares issuable pursuant to forward sale agreement (in shares)	4,460,000	1,500,000		11,960,000
Net proceeds from common shares issued directly by the Company	$ 314,100	$ 105,700			$ 419,786	$ 0
Forward sale price (in dollars per share)	$ 71.48
Common shares issued directly by the Company (in shares)					5,960,000
Treasury stock (in shares)			15,977,757		15,407,215
Common stock outstanding (in shares)			329,880,645		336,411,187

COMMON SHAREHOLDERS' EQUITY A_2

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Equity [Abstract]
Dividends on preferred stock	$ 1,880	$ 1,880
Noncontrolling interest attributed to preferred stock of subsidiaries	$ 155,570		$ 155,570

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Income Attributable to Common Shareholders	$ 334,753	$ 308,678
Weighted Average Common Shares Outstanding:
Basic (in shares)	331,102,237	317,624,593
Dilutive Effect of:
Share-Based Compensation Awards and Other (in shares)	747,233	691,489
Equity Forward Sale Agreement (in shares)	1,087,683	0
Dilutive Effect (in shares)	1,834,916	691,489
Diluted (in shares)	332,937,153	318,316,082
Basic EPS (in dollars per share)	$ 1.01	$ 0.97

REVENUES (Details)

REVENUES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	$ 2,294,400	$ 2,397,300
Alternative Revenue Programs	74,500	14,700
Other Revenues	4,800	3,800
Operating Revenues	2,373,726	2,415,792
Lease revenue	1,100	1,000
Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,229,600	1,319,200
Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	755,400	809,600
Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	106,000	111,400
Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,091,000	2,240,200
Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	70,000	67,600
Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	105,000	74,200
Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	26,400	17,600
Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,000	(2,300)
Other
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	294,600	258,100
Alternative Revenue Programs	0	0
Other Revenues	0	0
Operating Revenues	294,600	258,100
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	17,300	13,500
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	277,300	244,600
Other | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(564,000)	(520,000)
Alternative Revenue Programs	(27,400)	(11,100)
Other Revenues	0	0
Operating Revenues	(591,400)	(531,100)
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	(1,000)	(1,100)
Eliminations | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(3,200)	(2,700)
Eliminations | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(4,200)	(3,800)
Eliminations | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(283,600)	(270,800)
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	(276,200)	(245,400)
Eliminations | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Electric Distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,763,000	1,829,000
Alternative Revenue Programs	38,800	2,100
Other Revenues	3,500	2,800
Operating Revenues	1,805,300	1,833,900
Electric Distribution | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	963,800	1,033,300
Electric Distribution | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	607,000	652,600
Electric Distribution | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	79,800	82,100
Electric Distribution | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,650,600	1,768,000
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	91,000	51,500
Electric Distribution | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	19,100	12,600
Electric Distribution | Operating Segments | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,300	(3,100)
Natural Gas Distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	415,500	457,800
Alternative Revenue Programs	32,200	10,400
Other Revenues	900	700
Operating Revenues	448,600	468,900
Natural Gas Distribution | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	238,000	258,900
Natural Gas Distribution | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	134,600	143,800
Natural Gas Distribution | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	28,300	30,900
Natural Gas Distribution | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	400,900	433,600
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	13,200	21,700
Natural Gas Distribution | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	900	900
Natural Gas Distribution | Operating Segments | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	500	1,600
Electric Transmission | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	339,700	328,100
Alternative Revenue Programs	29,800	12,400
Other Revenues	200	0
Operating Revenues	369,700	340,500
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	336,300	324,900
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	3,400	3,200
Electric Transmission | Operating Segments | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
Water Distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	45,600	44,300
Alternative Revenue Programs	1,100	900
Other Revenues	200	300
Operating Revenues	46,900	45,500
Water Distribution | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	27,800	27,000
Water Distribution | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	14,800	14,300
Water Distribution | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,100	1,100
Water Distribution | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	43,700	42,400
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	800	1,000
Water Distribution | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,900	1,700
Water Distribution | Operating Segments | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(800)	(800)
CL&P
Disaggregation of Revenue [Line Items]
Operating Revenues	899,703	849,246
Lease revenue	200	200
CL&P | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	975,600	959,200
Alternative Revenue Programs	44,600	5,700
Other Revenues	1,700	1,000
CL&P | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	489,900	510,500
CL&P | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	226,400	236,700
CL&P | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	34,000	34,600
CL&P | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	750,300	781,800
CL&P | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	151,800	154,800
CL&P | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	64,700	13,700
CL&P | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	8,800	8,900
CL&P | Operating Segments | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
CL&P | Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	(122,200)	(116,700)
NSTAR Electric
Disaggregation of Revenue [Line Items]
Operating Revenues	733,833	797,612
Lease revenue	700	600
NSTAR Electric | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	819,600	887,300
Alternative Revenue Programs	19,300	7,300
Other Revenues	1,400	1,500
NSTAR Electric | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	331,000	371,000
NSTAR Electric | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	301,900	336,500
NSTAR Electric | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	26,800	28,800
NSTAR Electric | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	659,700	736,300
NSTAR Electric | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	134,800	122,600
NSTAR Electric | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	14,400	24,400
NSTAR Electric | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	10,700	4,000
NSTAR Electric | Operating Segments | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0
NSTAR Electric | Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	(106,500)	(98,500)
PSNH
Disaggregation of Revenue [Line Items]
Operating Revenues	276,368	276,435
PSNH | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	308,600	311,700
Alternative Revenue Programs	4,700	1,500
Other Revenues	600	300
PSNH | Operating Segments | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	142,900	151,800
PSNH | Operating Segments | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	79,100	79,800
PSNH | Operating Segments | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	19,000	18,700
PSNH | Operating Segments | Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	241,000	250,300
PSNH | Operating Segments | Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	49,700	47,500
PSNH | Operating Segments | Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	11,900	13,400
PSNH | Operating Segments | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,700	3,600
PSNH | Operating Segments | Amortization/(Reserve) for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,300	(3,100)
PSNH | Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	$ (37,500)	$ (37,100)

SEGMENT INFORMATION - Narrative

SEGMENT INFORMATION - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)segment
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]
Amount of natural gas transmission purchased | $	$ 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, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Operating Revenues	$ 2,373,726	$ 2,415,792
Depreciation and Amortization	(286,000)	(285,900)
Other Operating Expenses	(1,548,600)	(1,635,200)
Operating Income/(Loss)	539,120	494,700
Interest Expense	(134,715)	(131,734)
Other Income, Net	24,104	30,985
Net Income/(Loss) Attributable to Common Shareholders	334,753	308,678
Cash Flows Used for Investments in Plant	725,520	628,129
Assets	41,648,986		$ 41,123,915
Other
Segment Reporting Information [Line Items]
Operating Revenues	294,600	258,100
Depreciation and Amortization	(21,300)	(13,600)
Other Operating Expenses	(257,000)	(225,500)
Operating Income/(Loss)	16,300	19,000
Interest Expense	(42,700)	(44,200)
Other Income, Net	468,100	431,700
Net Income/(Loss) Attributable to Common Shareholders	442,200	407,500
Cash Flows Used for Investments in Plant	59,300	55,900
Assets	20,860,800		20,469,600
Eliminations
Segment Reporting Information [Line Items]
Operating Revenues	(591,400)	(531,100)
Depreciation and Amortization	600	600
Other Operating Expenses	591,400	531,000
Operating Income/(Loss)	600	500
Interest Expense	11,800	12,600
Other Income, Net	(463,200)	(427,600)
Net Income/(Loss) Attributable to Common Shareholders	(450,800)	(414,500)
Cash Flows Used for Investments in Plant	0	0
Assets	(20,284,300)		(19,488,800)
Electric Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	1,805,300	1,833,900
Depreciation and Amortization	(167,300)	(179,200)
Other Operating Expenses	(1,439,600)	(1,475,600)
Operating Income/(Loss)	198,400	179,100
Interest Expense	(53,100)	(49,200)
Other Income, Net	12,500	18,200
Net Income/(Loss) Attributable to Common Shareholders	130,100	120,100
Cash Flows Used for Investments in Plant	315,800	279,300
Assets	23,135,900		22,541,900
Natural Gas Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	448,600	468,900
Depreciation and Amortization	(19,100)	(20,400)
Other Operating Expenses	(311,600)	(341,300)
Operating Income/(Loss)	117,900	107,200
Interest Expense	(11,400)	(11,700)
Other Income, Net	1,400	200
Net Income/(Loss) Attributable to Common Shareholders	84,400	76,500
Cash Flows Used for Investments in Plant	99,100	87,400
Assets	4,430,400		4,345,500
Electric Transmission | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	369,700	340,500
Depreciation and Amortization	(67,500)	(61,500)
Other Operating Expenses	(106,800)	(98,800)
Operating Income/(Loss)	195,400	180,200
Interest Expense	(30,600)	(30,600)
Other Income, Net	5,200	8,100
Net Income/(Loss) Attributable to Common Shareholders	126,800	118,200
Cash Flows Used for Investments in Plant	232,800	184,800
Assets	11,137,500		10,904,000
Water Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	46,900	45,500
Depreciation and Amortization	(11,400)	(11,800)
Other Operating Expenses	(25,000)	(25,000)
Operating Income/(Loss)	10,500	8,700
Interest Expense	(8,700)	(8,600)
Other Income, Net	100	400
Net Income/(Loss) Attributable to Common Shareholders	2,100	900
Cash Flows Used for Investments in Plant	18,500	$ 20,700
Assets	$ 2,368,700		$ 2,351,700