NSTAR Electric Company PFD 4.25% (NSARP) 10-K 14 Feb 24 2023 FY Annual report Financial data

COVER PAGE

COVER PAGE - USD ($)	12 Months Ended
	Dec. 31, 2023	Jan. 31, 2024	Jun. 30, 2023
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
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	001-05324
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 24,734,207,777
Entity Common Stock, Shares Outstanding		349,687,183
Documents Incorporated by Reference	Documents Incorporated by Reference Portions of the Eversource Energy and Subsidiaries 2022 combined Annual Report on Form 10-K and portions of the Proxy Statement relating to the Annual Meeting of Shareholders to be held on May 1, 2024, are incorporated by reference into Parts II and III of this Report.
Entity Central Index Key	0000072741
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
The Connecticut Light and Power Company
Entity Information [Line Items]
Current Fiscal Year End Date	--12-31
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	000-00404
Entity Tax Identification Number	06-0303850
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		6,035,205
Entity Central Index Key	0000023426
NSTAR Electric Company
Entity Information [Line Items]
Current Fiscal Year End Date	--12-31
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	001-02301
Entity Tax Identification Number	04-1278810
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		200
Entity Central Index Key	0000013372
Public Service Company of New Hampshire
Entity Information [Line Items]
Current Fiscal Year End Date	--12-31
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	001-06392
Entity Tax Identification Number	02-0181050
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		301
Entity Central Index Key	0000315256

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut
CL&P
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut
NSTAR Electric
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut
PSNH
Auditor [Line Items]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Hartford, Connecticut

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current Assets:
Cash	$ 53,873	$ 47,597
Cash Equivalents	0	327,006
Receivables, Net (net of allowance for uncollectible accounts)	1,431,531	1,517,138
Unbilled Revenues	225,325	238,968
Materials, Supplies, Natural Gas and REC Inventory	507,307	374,395
Regulatory Assets	1,674,196	1,335,491
Prepayments and Other Current Assets	355,762	382,603
Total Current Assets	4,247,994	4,223,198
Property, Plant and Equipment, Net	39,498,607	36,112,820
Deferred Debits and Other Assets:
Regulatory Assets	4,714,970	4,242,794
Goodwill	4,532,100	4,522,632
Investments in Unconsolidated Affiliates	660,473	2,176,080
Prepaid Pension and PBOP	1,028,207	1,045,524
Marketable Securities	337,814	366,508
Other Long-Term Assets	592,080	541,344
Total Deferred Debits and Other Assets	11,865,644	12,894,882
Total Assets	55,612,245	53,230,900
Current Liabilities:
Notes Payable	1,930,422	1,442,200
Long-Term Debt – Current Portion	824,847	1,320,129
Rate Reduction Bonds – Current Portion	43,210	43,210
Accounts Payable	1,869,187	2,113,905
Regulatory Liabilities	591,750	890,786
Other Current Liabilities	1,081,981	989,053
Total Current Liabilities	6,341,397	6,799,283
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	5,303,730	5,067,902
Regulatory Liabilities	4,022,923	3,930,305
Derivative Liabilities	67,999	143,929
Asset Retirement Obligations	505,844	502,713
Accrued Pension, SERP and PBOP	123,754	135,473
Other Long-Term Liabilities	961,239	888,081
Total Deferred Credits and Other Liabilities	10,985,489	10,668,403
Capitalization:
Long-Term Debt	23,588,616	19,723,994
Rate Reduction Bonds	367,282	410,492
Noncontrolling Interest - Preferred Stock of Subsidiaries	155,569	155,570
Common Shareholders' Equity:
Common Shares	1,799,920	1,799,920
Capital Surplus, Paid In	8,460,876	8,401,731
Retained Earnings	4,142,515	5,527,153
Accumulated Other Comprehensive Income/(Loss)	(33,737)	(39,421)
Treasury Stock	(195,682)	(216,225)
Common Shareholders' Equity	14,173,892	15,473,158
Commitments and Contingencies (Note 13)
Total Liabilities and Capitalization	$ 55,612,245	$ 53,230,900

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Allowance for uncollectible accounts, current	$ 554,455	$ 486,297

CONSOLIDATED STATEMENTS OF (LOS

CONSOLIDATED STATEMENTS OF (LOSS)/INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Operating Revenues	$ 11,910,705	$ 12,289,336	$ 9,863,085
Operating Expenses:
Purchased Power, Purchased Natural Gas and Transmission	5,168,241	5,014,074	3,372,344
Operations and Maintenance	1,895,703	1,865,328	1,739,685
Depreciation	1,305,840	1,194,246	1,103,008
Amortization	(490,117)	448,892	231,965
Energy Efficiency Programs	691,344	658,051	592,775
Taxes Other Than Income Taxes	940,359	910,591	829,987
Total Operating Expenses	9,511,370	10,091,182	7,869,764
Operating Income	2,399,335	2,198,154	1,993,321
Interest Expense	855,441	678,274	582,334
Impairments of Offshore Wind Investments	2,167,000	0	0
Other Income, Net	348,069	346,088	161,282
(Loss)/Income Before Income Tax Expense	(275,037)	1,865,968	1,572,269
Income Tax Expense	159,684	453,574	344,223
Net (Loss)/Income	(434,721)	1,412,394	1,228,046
Net Income Attributable to Noncontrolling Interests	7,519	7,519	7,519
Net (Loss)/Income Attributable to Common Shareholders	$ (442,240)	$ 1,404,875	$ 1,220,527
Basic (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.27)	$ 4.05	$ 3.55
Diluted (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.26)	$ 4.05	$ 3.54
Weighted Average Common Shares Outstanding:
Basic (in shares)	349,580,638	346,783,444	343,972,926
Diluted (in shares)	349,840,481	347,246,768	344,631,056

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS)/INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net (Loss)/Income	$ (434,721)	$ 1,412,394	$ 1,228,046
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	20	20	972
Changes in Unrealized Gains/(Losses) on Marketable Securities	1,252	(1,636)	(671)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	4,412	4,470	33,835
Other Comprehensive Income, Net of Tax	5,684	2,854	34,136
Comprehensive Income Attributable to Noncontrolling Interests	(7,519)	(7,519)	(7,519)
Comprehensive (Loss)/Income Attributable to Common Shareholders	$ (436,556)	$ 1,407,729	$ 1,254,663

CONSOLIDATED STATEMENTS OF COMM

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
Beginning balance (in shares) at Dec. 31, 2020		342,954,023
Beginning balance at Dec. 31, 2020	$ 14,063,566	$ 1,789,092	$ 8,015,663	$ 4,613,201	$ (76,411)	$ (277,979)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,228,046			1,228,046
Dividends on Common Stock	(828,337)			(828,337)
Dividends on Preferred Stock	(7,519)			(7,519)
Long-Term Incentive Plan Activity	3,537		3,537
Issuance of Treasury Shares (in shares)		986,656
Issuance of Treasury Shares	68,364		49,913			18,451
Issuance of Treasury Shares for Acquisition (in shares)		462,517
Issuance of Treasury Shares for Acquisition	38,051		29,401			8,650
Other Comprehensive Income, Net of Tax	34,136				34,136
Ending balance (in shares) at Dec. 31, 2021		344,403,196
Ending balance at Dec. 31, 2021	14,599,844	$ 1,789,092	8,098,514	5,005,391	(42,275)	(250,878)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,412,394			1,412,394
Dividends on Common Stock	(883,113)			(883,113)
Dividends on Preferred Stock	(7,519)			(7,519)
Issuance of Common Shares (in shares)		2,165,671
Issuance of Common Shares	199,905	$ 10,828	189,077
Long-Term Incentive Plan Activity	8,335		8,335
Issuance of Treasury Shares (in shares)		949,724
Issuance of Treasury Shares	71,172		53,822			17,350
Capital Stock Expense	(2,847)		(2,847)
Issuance of Treasury Shares for Acquisition (in shares)		925,264
Issuance of Treasury Shares for Acquisition	72,133		54,830			17,303
Other Comprehensive Income, Net of Tax	$ 2,854				2,854
Ending balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855
Ending balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	(216,225)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	(434,721)			(434,721)
Dividends on Common Stock	(942,398)			(942,398)
Dividends on Preferred Stock	(7,519)			(7,519)
Long-Term Incentive Plan Activity	1,375		1,375
Issuance of Treasury Shares (in shares)		1,096,411
Issuance of Treasury Shares	78,313		57,770			20,543
Other Comprehensive Income, Net of Tax	$ 5,684				5,684
Ending balance (in shares) at Dec. 31, 2023	349,540,266	349,540,266
Ending balance at Dec. 31, 2023	$ 14,173,892	$ 1,799,920	$ 8,460,876	$ 4,142,515	$ (33,737)	$ (195,682)

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Dividends on Common Shares (in dollars per share)	$ 2.70	$ 2.55	$ 2.41
Par value of Common Shares (in dollars per share)	$ 5	$ 5

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net (Loss)/Income	$ (434,721)	$ 1,412,394	$ 1,228,046
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	1,305,840	1,194,246	1,103,008
Deferred Income Taxes	85,405	346,779	347,056
Uncollectible Expense	72,468	61,876	60,886
Pension, SERP and PBOP Income, Net	(90,706)	(160,857)	(14,693)
Pension and PBOP Contributions	(6,860)	(83,148)	(182,344)
Regulatory Under Recoveries, Net	(151,548)	(205,294)	(314,211)
(Customer Credits)/Reserve at CL&P related to PURA Settlement Agreement and Storm Performance Penalty	0	(72,041)	81,274
Amortization	(490,117)	448,892	231,965
Cost of Removal Expenditures	(315,699)	(303,755)	(242,130)
Payment in 2022 of Withheld Property Taxes	0	(78,446)	0
Impairments of Offshore Wind Investments	2,167,000	0	0
Other	(53,026)	(39,192)	(64,640)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(124,393)	(470,593)	(135,505)
Taxes Receivable/Accrued, Net	36,357	18,358	(110,621)
Accounts Payable	(287,637)	377,657	(29,201)
Other Current Assets and Liabilities, Net	(66,202)	(45,583)	3,710
Net Cash Flows Provided by Operating Activities	1,646,161	2,401,293	1,962,600
Investing Activities:
Investments in Property, Plant and Equipment	(4,336,849)	(3,441,852)	(3,175,080)
Proceeds from Sales of Marketable Securities	395,604	457,612	447,893
Purchases of Marketable Securities	(336,779)	(424,174)	(414,980)
Investments in Unconsolidated Affiliates	(1,680,473)	(742,496)	(327,385)
Proceeds from Unconsolidated Affiliates	1,090,662	0	0
Other Investing Activities	(2,897)	20,420	22,178
Net Cash Flows Used in Investing Activities	(4,870,732)	(4,130,490)	(3,447,374)
Financing Activities:
Issuance of Common Shares, Net of Issuance Costs	0	197,058	0
Cash Dividends on Common Shares	(918,995)	(860,033)	(805,439)
Cash Dividends on Preferred Stock	(7,519)	(7,519)	(7,519)
Increase/(Decrease) in Notes Payable	695,552	(78,170)	256,125
Repayment of Rate Reduction Bonds	(43,210)	(43,210)	(43,210)
Issuance of Long-Term Debt	5,198,345	4,045,000	3,230,000
Retirement of Long-Term Debt	(2,008,470)	(1,175,000)	(1,142,500)
Other Financing Activities	(46,466)	(48,185)	(46,625)
Net Cash Flows Provided by Financing Activities	2,869,237	2,029,941	1,440,832
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(355,334)	300,744	(43,942)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	521,752	221,008	264,950
Cash, Cash Equivalents and Restricted Cash - End of Year	$ 166,418	$ 521,752	$ 221,008

THE CONNECTICUT LIGHT AND POWER

THE CONNECTICUT LIGHT AND POWER COMPANY BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current Assets:
Cash	$ 53,873	$ 47,597
Receivables, Net (net of allowance for uncollectible accounts)	1,431,531	1,517,138
Unbilled Revenues	225,325	238,968
Materials, Supplies, Natural Gas and REC Inventory	507,307	374,395
Regulatory Assets	1,674,196	1,335,491
Prepayments and Other Current Assets	355,762	382,603
Total Current Assets	4,247,994	4,223,198
Property, Plant and Equipment, Net	39,498,607	36,112,820
Deferred Debits and Other Assets:
Regulatory Assets	4,714,970	4,242,794
Prepaid Pension and PBOP	1,028,207	1,045,524
Other Long-Term Assets	592,080	541,344
Total Deferred Debits and Other Assets	11,865,644	12,894,882
Total Assets	55,612,245	53,230,900
Current Liabilities:
Accounts Payable	1,869,187	2,113,905
Regulatory Liabilities	591,750	890,786
Other Current Liabilities	1,081,981	989,053
Total Current Liabilities	6,341,397	6,799,283
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	5,303,730	5,067,902
Regulatory Liabilities	4,022,923	3,930,305
Derivative Liabilities	67,999	143,929
Other Long-Term Liabilities	961,239	888,081
Total Deferred Credits and Other Liabilities	10,985,489	10,668,403
Capitalization:
Long-Term Debt	23,588,616	19,723,994
Noncontrolling Interest - Preferred Stock of Subsidiaries	155,569	155,570
Common Shareholders' Equity:
Capital Surplus, Paid In	8,460,876	8,401,731
Retained Earnings	4,142,515	5,527,153
Accumulated Other Comprehensive Income/(Loss)	(33,737)	(39,421)
Stockholders' equity	14,173,892	15,473,158
Commitments and Contingencies (Note 13)
Total Liabilities and Capitalization	55,612,245	53,230,900
The Connecticut Light and Power Company
Current Assets:
Cash	10,213	11,312
Unbilled Revenues	57,403	59,363
Materials, Supplies, Natural Gas and REC Inventory	156,467	88,157
Taxes Receivable	41,253	65,785
Regulatory Assets	480,369	314,089
Prepayments and Other Current Assets	53,536	62,524
Total Current Assets	1,418,684	1,259,721
Property, Plant and Equipment, Net	12,340,192	11,467,024
Deferred Debits and Other Assets:
Regulatory Assets	1,662,778	1,593,693
Prepaid Pension and PBOP	129,801	147,914
Other Long-Term Assets	298,169	290,444
Total Deferred Debits and Other Assets	2,090,748	2,032,051
Total Assets	15,849,624	14,758,796
Current Liabilities:
Notes Payable to Eversource Parent	249,670	0
Obligations to Third Party Suppliers	75,753	40,704
Regulatory Liabilities	102,239	336,048
Derivative Liabilities	81,944	81,588
Other Current Liabilities	127,703	123,171
Total Current Liabilities	1,394,090	1,428,288
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,860,122	1,640,034
Regulatory Liabilities	1,315,928	1,263,396
Derivative Liabilities	67,999	143,929
Other Long-Term Liabilities	190,186	166,081
Total Deferred Credits and Other Liabilities	3,434,235	3,213,440
Capitalization:
Long-Term Debt	4,814,429	4,216,488
Noncontrolling Interest - Preferred Stock of Subsidiaries	116,200	116,200
Common Shareholders' Equity:
Common Stock	60,352	60,352
Capital Surplus, Paid In	3,384,265	3,260,765
Retained Earnings	2,645,868	2,463,094
Accumulated Other Comprehensive Income/(Loss)	185	169
Stockholders' equity	6,090,670	5,784,380
Commitments and Contingencies (Note 13)
Total Liabilities and Capitalization	15,849,624	14,758,796
The Connecticut Light and Power Company | Nonrelated Party
Current Assets:
Receivables, Net (net of allowance for uncollectible accounts)	558,993	612,052
Current Liabilities:
Accounts Payable	622,055	710,500
The Connecticut Light and Power Company | Related Party
Current Assets:
Receivables, Net (net of allowance for uncollectible accounts)	60,450	46,439
Current Liabilities:
Notes Payable to Eversource Parent	457,000
Accounts Payable	134,726	$ 136,277
Capitalization:
Long-Term Debt	$ 207,300

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Allowance for uncollectible accounts, current	$ 554,455	$ 486,297
CL&P
Allowance for uncollectible accounts, current	$ 296,030	$ 225,320

THE CONNECTICUT LIGHT AND POW_2

THE CONNECTICUT LIGHT AND POWER COMPANY STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Revenues	$ 11,910,705	$ 12,289,336	$ 9,863,085
Operating Expenses:
Purchased Power and Transmission	5,168,241	5,014,074	3,372,344
Operations and Maintenance	1,895,703	1,865,328	1,739,685
Depreciation	1,305,840	1,194,246	1,103,008
Energy Efficiency Programs	691,344	658,051	592,775
Taxes Other Than Income Taxes	940,359	910,591	829,987
Total Operating Expenses	9,511,370	10,091,182	7,869,764
Operating Income	2,399,335	2,198,154	1,993,321
Interest Expense	855,441	678,274	582,334
Other Income, Net	348,069	346,088	161,282
(Loss)/Income Before Income Tax Expense	(275,037)	1,865,968	1,572,269
Income Tax Expense	159,684	453,574	344,223
Net (Loss)/Income	(434,700)	1,412,400	1,228,000
The Connecticut Light and Power Company
Operating Revenues	4,578,804	4,817,744	3,637,412
Operating Expenses:
Purchased Power and Transmission	2,612,949	2,110,253	1,392,969
Operations and Maintenance	733,287	707,162	644,175
Depreciation	376,904	355,511	338,915
Amortization of Regulatory (Liabilities)/Assets, Net	(500,367)	335,636	99,009
Energy Efficiency Programs	133,453	134,222	129,564
Taxes Other Than Income Taxes	401,135	384,746	363,862
Total Operating Expenses	3,757,361	4,027,530	2,968,494
Operating Income	821,443	790,214	668,918
Interest Expense	193,361	169,348	166,107
Other Income, Net	61,560	83,252	30,187
(Loss)/Income Before Income Tax Expense	689,642	704,118	532,998
Income Tax Expense	170,909	171,198	131,273
Net (Loss)/Income	$ 518,733	$ 532,920	$ 401,725

THE CONNECTICUT LIGHT AND POW_3

THE CONNECTICUT LIGHT AND POWER COMPANY STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Other Comprehensive Income, Net of Tax:
Other Comprehensive Income/(Loss), Net of Tax	5,700	2,900
Comprehensive (Loss)/Income	(436,556)	1,407,729	1,254,663
The Connecticut Light and Power Company
Net (Loss)/Income	518,733	532,920	401,725
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	(26)	(26)	(26)
Changes in Unrealized Gains/(Losses) on Marketable Securities	42	(56)	(25)
Other Comprehensive Income/(Loss), Net of Tax	16	(82)	(51)
Comprehensive (Loss)/Income	$ 518,749	$ 532,838	$ 401,674

THE CONNECTICUT LIGHT AND POW_4

THE CONNECTICUT LIGHT AND POWER COMPANY STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital Surplus, Paid In	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	The Connecticut Light and Power Company	The Connecticut Light and Power Company Common Stock	The Connecticut Light and Power Company Capital Surplus, Paid In	The Connecticut Light and Power Company Retained Earnings	The Connecticut Light and Power Company Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2020		342,954,023					6,035,205
Beginning balance at Dec. 31, 2020	$ 14,063,566	$ 1,789,092	$ 8,015,663	$ 4,613,201	$ (76,411)	$ 5,044,786	$ 60,352	$ 2,810,765	$ 2,173,367	$ 302
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,228,000					401,725			401,725
Dividends on Preferred Stock	(7,519)			(7,519)		(5,559)			(5,559)
Dividends on Common Stock	(828,337)			(828,337)		(341,400)			(341,400)
Capital Contributions from Eversource Parent						200,000		200,000
Other Comprehensive (Loss)/Income, Net of Tax						(51)				(51)
Ending balance (in shares) at Dec. 31, 2021		344,403,196					6,035,205
Ending balance at Dec. 31, 2021	14,599,844	$ 1,789,092	8,098,514	5,005,391	(42,275)	5,299,501	$ 60,352	3,010,765	2,228,133	251
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,412,400					532,920			532,920
Dividends on Preferred Stock	(7,519)			(7,519)		(5,559)			(5,559)
Dividends on Common Stock	(883,113)			(883,113)		(292,400)			(292,400)
Capital Contributions from Eversource Parent	210,000					250,000		250,000
Other Comprehensive (Loss)/Income, Net of Tax	$ 2,900					(82)				(82)
Ending balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855					6,035,205
Ending balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	5,784,380	$ 60,352	3,260,765	2,463,094	169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	(434,700)					518,733			518,733
Dividends on Preferred Stock	(7,519)			(7,519)		(5,559)			(5,559)
Dividends on Common Stock	(942,398)			(942,398)		(330,400)			(330,400)
Capital Contributions from Eversource Parent						123,500		123,500
Other Comprehensive (Loss)/Income, Net of Tax	$ 5,700					16				16
Ending balance (in shares) at Dec. 31, 2023	349,540,266	349,540,266					6,035,205
Ending balance at Dec. 31, 2023	$ 14,173,892	$ 1,799,920	$ 8,460,876	$ 4,142,515	$ (33,737)	$ 6,090,670	$ 60,352	$ 3,384,265	$ 2,645,868	$ 185

THE CONNECTICUT LIGHT AND POW_5

THE CONNECTICUT LIGHT AND POWER COMPANY STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	1,305,840	1,194,246	1,103,008
Deferred Income Taxes	85,405	346,779	347,056
Uncollectible Expense	72,468	61,876	60,886
Pension, SERP and PBOP (Income)/Expense, Net	(90,706)	(160,857)	(14,693)
Pension Contributions	(6,860)	(83,148)	(182,344)
Regulatory Over/(Under) Recoveries, Net	(151,548)	(205,294)	(314,211)
(Customer Credits)/Reserve at CL&P related to PURA Settlement Agreement and Storm Performance Penalty	0	(72,041)	81,274
Cost of Removal Expenditures	(315,699)	(303,755)	(242,130)
Other	(53,026)	(39,192)	(64,640)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(124,393)	(470,593)	(135,505)
Taxes Receivable/Accrued, Net	36,357	18,358	(110,621)
Accounts Payable	(287,637)	377,657	(29,201)
Other Current Assets and Liabilities, Net	(66,202)	(45,583)	3,710
Net Cash Flows Provided by Operating Activities	1,646,161	2,401,293	1,962,600
Investing Activities:
Investments in Property, Plant and Equipment	(4,336,849)	(3,441,852)	(3,175,080)
Other Investing Activities	(2,897)	20,420	22,178
Net Cash Flows Used in Investing Activities	(4,870,732)	(4,130,490)	(3,447,374)
Financing Activities:
Cash Dividends on Common Shares	(918,995)	(860,033)	(805,439)
Cash Dividends on Preferred Stock	(7,519)	(7,519)	(7,519)
Increase (Decrease) in Notes Payable To Eversource Parent	695,552	(78,170)	256,125
Issuance of Long-Term Debt	5,198,345	4,045,000	3,230,000
Retirement of Long-Term Debt	(2,008,470)	(1,175,000)	(1,142,500)
Other Financing Activities	(46,466)	(48,185)	(46,625)
Net Cash Flows Provided by/(Used In) Financing Activities	2,869,237	2,029,941	1,440,832
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(355,334)	300,744	(43,942)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	521,752	221,008	264,950
Cash, Cash Equivalents and Restricted Cash - End of Year	166,418	521,752	221,008
The Connecticut Light and Power Company
Operating Activities:
Net (Loss)/Income	518,733	532,920	401,725
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	376,904	355,511	338,915
Deferred Income Taxes	184,037	45,381	123,889
Uncollectible Expense	11,675	15,578	13,495
Pension, SERP and PBOP (Income)/Expense, Net	(18,316)	(28,971)	5,295
Pension Contributions	0	0	(98,913)
Regulatory Over/(Under) Recoveries, Net	157,200	(144,793)	(152,775)
(Customer Credits)/Reserve at CL&P related to PURA Settlement Agreement and Storm Performance Penalty	0	(72,041)	81,274
Amortization of Regulatory (Liabilities)/Assets, Net	(500,367)	335,636	99,009
Cost of Removal Expenditures	(80,479)	(71,596)	(95,792)
Other	(16,194)	(25,927)	(10,194)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(100,684)	(256,338)	(75,881)
Taxes Receivable/Accrued, Net	25,633	897	(25,162)
Accounts Payable	(88,040)	207,698	24,895
Other Current Assets and Liabilities, Net	(20,535)	(24,308)	(16,925)
Net Cash Flows Provided by Operating Activities	449,567	869,647	612,855
Investing Activities:
Investments in Property, Plant and Equipment	(1,093,121)	(876,740)	(790,083)
Other Investing Activities	173	591	329
Net Cash Flows Used in Investing Activities	(1,092,948)	(876,149)	(789,754)
Financing Activities:
Cash Dividends on Common Shares	(330,400)	(292,400)	(341,400)
Cash Dividends on Preferred Stock	(5,559)	(5,559)	(5,559)
Increase (Decrease) in Notes Payable To Eversource Parent	457,000	0	0
Issuance of Long-Term Debt	800,000	0	425,000
Retirement of Long-Term Debt	(400,000)	0	(120,500)
Capital Contributions from Eversource Parent	123,500	250,000	200,000
Other Financing Activities	(9,244)	0	(5,663)
Net Cash Flows Provided by/(Used In) Financing Activities	635,297	(47,959)	151,878
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(8,084)	(54,461)	(25,021)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	20,327	74,788	99,809
Cash, Cash Equivalents and Restricted Cash - End of Year	$ 12,243	$ 20,327	$ 74,788

NSTAR ELECTRIC COMPANY AND SUBS

NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current Assets:
Cash	$ 53,873	$ 47,597
Cash Equivalents	0	327,006
Receivables, Net (net of allowance for uncollectible accounts)	1,431,531	1,517,138
Unbilled Revenues	225,325	238,968
Materials, Supplies, Natural Gas and REC Inventory	507,307	374,395
Regulatory Assets	1,674,196	1,335,491
Prepayments and Other Current Assets	355,762	382,603
Total Current Assets	4,247,994	4,223,198
Property, Plant and Equipment, Net	39,498,607	36,112,820
Deferred Debits and Other Assets:
Regulatory Assets	4,714,970	4,242,794
Prepaid Pension and PBOP	1,028,207	1,045,524
Other Long-Term Assets	592,080	541,344
Total Deferred Debits and Other Assets	11,865,644	12,894,882
Total Assets	55,612,245	53,230,900
Current Liabilities:
Long-Term Debt – Current Portion	824,847	1,320,129
Accounts Payable	1,869,187	2,113,905
Regulatory Liabilities	591,750	890,786
Other Current Liabilities	1,081,981	989,053
Total Current Liabilities	6,341,397	6,799,283
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	5,303,730	5,067,902
Regulatory Liabilities	4,022,923	3,930,305
Other Long-Term Liabilities	961,239	888,081
Total Deferred Credits and Other Liabilities	10,985,489	10,668,403
Capitalization:
Long-Term Debt	23,588,616	19,723,994
Preferred Stock Not Subject to Mandatory Redemption	155,569	155,570
Common Shareholders' Equity:
Capital Surplus, Paid In	8,460,876	8,401,731
Retained Earnings	4,142,515	5,527,153
Accumulated Other Comprehensive Income/(Loss)	(33,737)	(39,421)
Common Shareholders' Equity	14,173,892	15,473,158
Commitments and Contingencies (Note 13)
Total Liabilities and Capitalization	55,612,245	53,230,900
NSTAR Electric Company
Current Assets:
Cash	6,740	738
Cash Equivalents	0	327,006
Unbilled Revenues	49,897	39,680
Materials, Supplies, Natural Gas and REC Inventory	173,770	138,352
Regulatory Assets	676,083	492,759
Prepayments and Other Current Assets	41,464	71,276
Total Current Assets	1,510,295	1,558,378
Property, Plant and Equipment, Net	12,753,787	11,626,968
Deferred Debits and Other Assets:
Regulatory Assets	1,281,836	1,221,619
Prepaid Pension and PBOP	608,617	576,809
Other Long-Term Assets	116,978	111,846
Total Deferred Debits and Other Assets	2,007,431	1,910,274
Total Assets	16,271,513	15,095,620
Current Liabilities:
Notes Payable to Eversource Parent	365,847	0
Long-Term Debt – Current Portion	0	80,000
Obligations to Third Party Suppliers	139,823	142,628
Renewable Portfolio Standards Compliance Obligations	116,010	120,239
Regulatory Liabilities	368,070	373,221
Other Current Liabilities	84,688	83,925
Total Current Liabilities	1,818,756	1,468,596
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,849,613	1,700,875
Regulatory Liabilities	1,585,311	1,548,081
Other Long-Term Liabilities	327,388	289,313
Total Deferred Credits and Other Liabilities	3,762,312	3,538,269
Capitalization:
Long-Term Debt	4,496,947	4,345,085
Preferred Stock Not Subject to Mandatory Redemption	43,000	43,000
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	3,013,842	2,778,942
Retained Earnings	3,136,612	2,921,444
Accumulated Other Comprehensive Income/(Loss)	44	284
Common Shareholders' Equity	6,150,498	5,700,670
Commitments and Contingencies (Note 13)
Total Liabilities and Capitalization	16,271,513	15,095,620
NSTAR Electric Company | Nonrelated Party
Current Assets:
Receivables, Net (net of allowance for uncollectible accounts)	487,707	453,371
Current Liabilities:
Accounts Payable	599,696	559,676
NSTAR Electric Company | Related Party
Current Assets:
Receivables, Net (net of allowance for uncollectible accounts)	74,634	35,196
Current Liabilities:
Accounts Payable	$ 144,622	$ 108,907

NSTAR ELECTRIC COMPANY AND SU_2

NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Allowance for uncollectible accounts, current	$ 554,455	$ 486,297
NSTAR Electric
Allowance for uncollectible accounts, current	$ 97,026	$ 94,958

NSTAR ELECTRIC COMPANY AND SU_3

NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Revenues	$ 11,910,705	$ 12,289,336	$ 9,863,085
Operating Expenses:
Purchased Power and Transmission	5,168,241	5,014,074	3,372,344
Operations and Maintenance	1,895,703	1,865,328	1,739,685
Depreciation	1,305,840	1,194,246	1,103,008
Energy Efficiency Programs	691,344	658,051	592,775
Taxes Other Than Income Taxes	940,359	910,591	829,987
Total Operating Expenses	9,511,370	10,091,182	7,869,764
Operating Income	2,399,335	2,198,154	1,993,321
Interest Expense	855,441	678,274	582,334
Other Income, Net	348,069	346,088	161,282
(Loss)/Income Before Income Tax Expense	(275,037)	1,865,968	1,572,269
Income Tax Expense	159,684	453,574	344,223
Net (Loss)/Income	(434,700)	1,412,400	1,228,000
NSTAR Electric Company
Operating Revenues	3,515,539	3,583,070	3,056,350
Operating Expenses:
Purchased Power and Transmission	1,154,013	1,264,824	932,530
Operations and Maintenance	668,466	640,834	563,172
Depreciation	372,578	361,969	337,451
Amortization of Regulatory (Liabilities)/Assets, Net	16,150	83,855	55,774
Energy Efficiency Programs	325,593	332,247	288,612
Taxes Other Than Income Taxes	256,090	246,705	216,703
Total Operating Expenses	2,792,890	2,930,434	2,394,242
Operating Income	722,649	652,636	662,108
Interest Expense	189,254	162,892	146,048
Other Income, Net	164,129	142,661	74,844
(Loss)/Income Before Income Tax Expense	697,524	632,405	590,904
Income Tax Expense	152,996	139,977	114,335
Net (Loss)/Income	$ 544,528	$ 492,428	$ 476,569

NSTAR ELECTRIC COMPANY AND SU_4

NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Other Comprehensive Income/(Loss), Net of Tax:
Other Comprehensive Income/(Loss), Net of Tax	5,700	2,900
Comprehensive (Loss)/Income Attributable to Common Shareholders	(436,556)	1,407,729	1,254,663
NSTAR Electric Company
Net (Loss)/Income	544,528	492,428	476,569
Other Comprehensive Income/(Loss), Net of Tax:
Changes in Funded Status of SERP Benefit Plan	(272)	(221)	(100)
Qualified Cash Flow Hedging Instruments	20	20	298
Changes in Unrealized Gains/(Losses) on Marketable Securities	12	(16)	(6)
Other Comprehensive Income/(Loss), Net of Tax	(240)	(217)	192
Comprehensive (Loss)/Income Attributable to Common Shareholders	$ 544,288	$ 492,211	$ 476,761

NSTAR ELECTRIC COMPANY AND SU_5

NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital Surplus, Paid In	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	NSTAR Electric	NSTAR Electric Common Stock	NSTAR Electric Capital Surplus, Paid In	NSTAR Electric Retained Earnings	NSTAR Electric Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2020		342,954,023					200
Beginning balance at Dec. 31, 2020	$ 14,063,566	$ 1,789,092	$ 8,015,663	$ 4,613,201	$ (76,411)	$ 4,521,418	$ 0	$ 1,993,942	$ 2,527,167	$ 309
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,228,000					476,569			476,569
Dividends on Preferred Stock	(7,519)			(7,519)		(1,960)			(1,960)
Dividends on Common Stock	(828,337)			(828,337)		(283,200)			(283,200)
Capital Contributions from Eversource Parent						260,000		260,000
Other Comprehensive (Loss)/Income, Net of Tax						192				192
Ending balance (in shares) at Dec. 31, 2021		344,403,196					200
Ending balance at Dec. 31, 2021	14,599,844	$ 1,789,092	8,098,514	5,005,391	(42,275)	4,973,019	$ 0	2,253,942	2,718,576	501
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,412,400					492,428			492,428
Dividends on Preferred Stock	(7,519)			(7,519)		(1,960)			(1,960)
Dividends on Common Stock	(883,113)			(883,113)		(287,600)			(287,600)
Capital Contributions from Eversource Parent	210,000					525,000		525,000
Other Comprehensive (Loss)/Income, Net of Tax	$ 2,900					(217)				(217)
Ending balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855					200
Ending balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	5,700,670	$ 0	2,778,942	2,921,444	284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	(434,700)					544,528			544,528
Dividends on Preferred Stock	(7,519)			(7,519)		(1,960)			(1,960)
Dividends on Common Stock	(942,398)			(942,398)		(327,400)			(327,400)
Capital Contributions from Eversource Parent						234,900		234,900
Other Comprehensive (Loss)/Income, Net of Tax	$ 5,700					(240)				(240)
Ending balance (in shares) at Dec. 31, 2023	349,540,266	349,540,266					200
Ending balance at Dec. 31, 2023	$ 14,173,892	$ 1,799,920	$ 8,460,876	$ 4,142,515	$ (33,737)	$ 6,150,498	$ 0	$ 3,013,842	$ 3,136,612	$ 44

NSTAR ELECTRIC COMPANY AND SU_6

NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	1,305,840	1,194,246	1,103,008
Deferred Income Taxes	85,405	346,779	347,056
Uncollectible Expense	72,468	61,876	60,886
Pension, SERP and PBOP Income, Net	(90,706)	(160,857)	(14,693)
Pension Contributions	(6,860)	(83,148)	(182,344)
Regulatory Under Recoveries, Net	(151,548)	(205,294)	(314,211)
Cost of Removal Expenditures	(315,699)	(303,755)	(242,130)
Payment in 2022 of Withheld Property Taxes	0	(78,446)	0
Other	(53,026)	(39,192)	(64,640)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(124,393)	(470,593)	(135,505)
Taxes Receivable/Accrued, Net	36,357	18,358	(110,621)
Accounts Payable	(287,637)	377,657	(29,201)
Other Current Assets and Liabilities, Net	(66,202)	(45,583)	3,710
Net Cash Flows Provided by Operating Activities	1,646,161	2,401,293	1,962,600
Investing Activities:
Investments in Property, Plant and Equipment	(4,336,849)	(3,441,852)	(3,175,080)
Other Investing Activities	(2,897)	20,420	22,178
Net Cash Flows Used in Investing Activities	(4,870,732)	(4,130,490)	(3,447,374)
Financing Activities:
Cash Dividends on Common Shares	(918,995)	(860,033)	(805,439)
Cash Dividends on Preferred Stock	(7,519)	(7,519)	(7,519)
Increase (Decrease) in Notes Payable To Eversource Parent	695,552	(78,170)	256,125
Issuance of Long-Term Debt	5,198,345	4,045,000	3,230,000
Retirement of Long-Term Debt	(2,008,470)	(1,175,000)	(1,142,500)
Other Financing Activities	(46,466)	(48,185)	(46,625)
Net Cash Flows Provided by Financing Activities	2,869,237	2,029,941	1,440,832
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(355,334)	300,744	(43,942)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	521,752	221,008	264,950
Cash, Cash Equivalents and Restricted Cash - End of Year	166,418	521,752	221,008
NSTAR Electric
Operating Activities:
Net (Loss)/Income	544,528	492,428	476,569
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	372,578	361,969	337,451
Deferred Income Taxes	96,224	78,039	57,507
Uncollectible Expense	22,791	21,550	16,649
Pension, SERP and PBOP Income, Net	(41,554)	(55,830)	(26,120)
Pension Contributions	0	(15,000)	(30,000)
Regulatory Under Recoveries, Net	(141,865)	(88,220)	(79,075)
Amortization of Regulatory (Liabilities)/Assets, Net	16,150	83,855	55,774
Cost of Removal Expenditures	(68,290)	(57,339)	(58,967)
Payment in 2022 of Withheld Property Taxes	0	(76,311)	0
Other	(2,123)	(14,294)	(32,447)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(82,659)	(23,757)	(45,774)
Taxes Receivable/Accrued, Net	27,394	35,143	(16,219)
Accounts Payable	11,357	8,815	31,650
Other Current Assets and Liabilities, Net	(40,974)	20,430	13,944
Net Cash Flows Provided by Operating Activities	713,557	771,478	700,942
Investing Activities:
Investments in Property, Plant and Equipment	(1,376,135)	(954,281)	(960,949)
Other Investing Activities	48	165	91
Net Cash Flows Used in Investing Activities	(1,376,087)	(954,116)	(960,858)
Financing Activities:
Cash Dividends on Common Shares	(327,400)	(287,600)	(283,200)
Cash Dividends on Preferred Stock	(1,960)	(1,960)	(1,960)
Increase/(Decrease) in Notes Payable	365,847	(162,500)	(32,500)
Increase (Decrease) in Notes Payable To Eversource Parent	0	0	(21,300)
Capital Contributions from Eversource Parent	234,900	525,000	260,000
Issuance of Long-Term Debt	150,000	850,000	600,000
Retirement of Long-Term Debt	(80,000)	(400,000)	(250,000)
Other Financing Activities	(1,365)	(13,188)	(10,355)
Net Cash Flows Provided by Financing Activities	340,022	509,752	260,685
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(322,508)	327,114	769
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	345,293	18,179	17,410
Cash, Cash Equivalents and Restricted Cash - End of Year	$ 22,785	$ 345,293	$ 18,179

PUBLIC SERVICE COMPANY OF NEW H

PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE AND SUBSIDIARIES CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current Assets:
Cash	$ 53,873	$ 47,597
Receivables, Net (net of allowance for uncollectible accounts)	1,431,531	1,517,138
Unbilled Revenues	225,325	238,968
Materials, Supplies and REC Inventory	507,307	374,395
Regulatory Assets	1,674,196	1,335,491
Prepayments and Other Current Assets	355,762	382,603
Total Current Assets	4,247,994	4,223,198
Property, Plant and Equipment, Net	39,498,607	36,112,820
Deferred Debits and Other Assets:
Regulatory Assets	4,714,970	4,242,794
Prepaid Pension and PBOP	1,028,207	1,045,524
Other Long-Term Assets	592,080	541,344
Total Deferred Debits and Other Assets	11,865,644	12,894,882
Total Assets	55,612,245	53,230,900
Current Liabilities:
Long-Term Debt – Current Portion	824,847	1,320,129
Rate Reduction Bonds – Current Portion	43,210	43,210
Accounts Payable	1,869,187	2,113,905
Regulatory Liabilities	591,750	890,786
Other Current Liabilities	1,081,981	989,053
Total Current Liabilities	6,341,397	6,799,283
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	5,303,730	5,067,902
Regulatory Liabilities	4,022,923	3,930,305
Other Long-Term Liabilities	961,239	888,081
Total Deferred Credits and Other Liabilities	10,985,489	10,668,403
Capitalization:
Long-Term Debt	23,588,616	19,723,994
Rate Reduction Bonds	367,282	410,492
Common Shareholders' Equity:
Capital Surplus, Paid In	8,460,876	8,401,731
Retained Earnings	4,142,515	5,527,153
Accumulated Other Comprehensive Income/(Loss)	(33,737)	(39,421)
Common Shareholders' Equity	14,173,892	15,473,158
Commitments and Contingencies (Note 13)
Total Liabilities and Capitalization	55,612,245	53,230,900
PSNH
Current Assets:
Cash	240	136
Unbilled Revenues	55,012	72,713
Taxes Receivable	27,146	27,978
Materials, Supplies and REC Inventory	77,066	34,521
Regulatory Assets	189,450	102,240
Special Deposits	31,586	33,140
Prepayments and Other Current Assets	18,489	13,297
Total Current Assets	569,479	465,555
Property, Plant and Equipment, Net	4,574,652	4,060,224
Deferred Debits and Other Assets:
Regulatory Assets	773,783	593,974
Prepaid Pension and PBOP	58,979	66,384
Other Long-Term Assets	16,558	16,517
Total Deferred Debits and Other Assets	849,320	676,875
Total Assets	5,993,451	5,202,654
Current Liabilities:
Notes Payable to Eversource Parent	233,000	173,300
Long-Term Debt – Current Portion	0	29,668
Rate Reduction Bonds – Current Portion	43,210	43,210
Regulatory Liabilities	117,515	161,963
Other Current Liabilities	72,328	59,616
Total Current Liabilities	713,069	795,544
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	691,532	562,802
Regulatory Liabilities	393,574	391,628
Other Long-Term Liabilities	42,484	37,087
Total Deferred Credits and Other Liabilities	1,127,590	991,517
Capitalization:
Long-Term Debt	1,431,591	1,134,914
Rate Reduction Bonds	367,282	410,492
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	1,698,134	1,298,134
Retained Earnings	655,785	572,126
Accumulated Other Comprehensive Income/(Loss)	0	(73)
Common Shareholders' Equity	2,353,919	1,870,187
Commitments and Contingencies (Note 13)
Total Liabilities and Capitalization	5,993,451	5,202,654
PSNH | Nonrelated Party
Current Assets:
Receivables, Net (net of allowance for uncollectible accounts)	152,276	173,337
Current Liabilities:
Accounts Payable	205,744	291,556
PSNH | Related Party
Current Assets:
Receivables, Net (net of allowance for uncollectible accounts)	18,214	8,193
Current Liabilities:
Notes Payable to Eversource Parent	233,000	173,300
Accounts Payable	$ 41,272	$ 36,231

PUBLIC SERVICE COMPANY OF NEW_2

PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE AND SUBSIDIARIES CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Allowance for uncollectible accounts, current	$ 554,455	$ 486,297
PSNH
Allowance for uncollectible accounts, current	$ 14,322	$ 29,236

PUBLIC SERVICE COMPANY OF NEW_3

PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Revenues	$ 11,910,705	$ 12,289,336	$ 9,863,085
Operating Expenses:
Purchased Power and Transmission	5,168,241	5,014,074	3,372,344
Operations and Maintenance	1,895,703	1,865,328	1,739,685
Depreciation	1,305,840	1,194,246	1,103,008
Energy Efficiency Programs	691,344	658,051	592,775
Taxes Other Than Income Taxes	940,359	910,591	829,987
Total Operating Expenses	9,511,370	10,091,182	7,869,764
Operating Income	2,399,335	2,198,154	1,993,321
Interest Expense	855,441	678,274	582,334
Other Income, Net	348,069	346,088	161,282
(Loss)/Income Before Income Tax Expense	(275,037)	1,865,968	1,572,269
Income Tax Expense	159,684	453,574	344,223
Net (Loss)/Income	(434,700)	1,412,400	1,228,000
PSNH
Operating Revenues	1,447,873	1,474,799	1,177,248
Operating Expenses:
Purchased Power and Transmission	604,983	665,478	370,271
Operations and Maintenance	284,442	255,991	237,659
Depreciation	140,417	127,962	120,065
Amortization of Regulatory (Liabilities)/Assets, Net	(16,343)	42,867	86,832
Energy Efficiency Programs	39,618	37,434	38,752
Taxes Other Than Income Taxes	93,894	95,301	91,465
Total Operating Expenses	1,147,011	1,225,033	945,044
Operating Income	300,862	249,766	232,204
Interest Expense	72,786	59,548	56,998
Other Income, Net	26,597	32,666	14,565
(Loss)/Income Before Income Tax Expense	254,673	222,884	189,771
Income Tax Expense	59,014	51,314	39,433
Net (Loss)/Income	$ 195,659	$ 171,570	$ 150,338

PUBLIC SERVICE COMPANY OF NEW_4

PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Other Comprehensive Income/(Loss), Net of Tax:
Other Comprehensive Income/(Loss), Net of Tax	5,700	2,900
Comprehensive (Loss)/Income Attributable to Common Shareholders	(436,556)	1,407,729	1,254,663
PSNH
Net (Loss)/Income	195,659	171,570	150,338
Other Comprehensive Income/(Loss), Net of Tax:
Qualified Cash Flow Hedging Instruments	0	0	673
Changes in Unrealized Gains/(Losses) on Marketable Securities	73	(96)	(37)
Other Comprehensive Income/(Loss), Net of Tax	73	(96)	636
Comprehensive (Loss)/Income Attributable to Common Shareholders	$ 195,732	$ 171,474	$ 150,974

PUBLIC SERVICE COMPANY OF NEW_5

PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital Surplus, Paid In	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	PSNH	PSNH Common Stock	PSNH Capital Surplus, Paid In	PSNH Retained Earnings	PSNH Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2020		342,954,023					301
Beginning balance at Dec. 31, 2020	$ 14,063,566	$ 1,789,092	$ 8,015,663	$ 4,613,201	$ (76,411)	$ 1,542,539	$ 0	$ 928,134	$ 615,018	$ (613)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,228,000					150,338			150,338
Dividends on Common Stock	(828,337)			(828,337)		(260,800)			(260,800)
Capital Contributions from Eversource Parent						160,000		160,000
Other Comprehensive (Loss)/Income, Net of Tax						636				636
Ending balance (in shares) at Dec. 31, 2021		344,403,196					301
Ending balance at Dec. 31, 2021	14,599,844	$ 1,789,092	8,098,514	5,005,391	(42,275)	1,592,713	$ 0	1,088,134	504,556	23
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	1,412,400					171,570			171,570
Dividends on Common Stock	(883,113)			(883,113)		(104,000)			(104,000)
Capital Contributions from Eversource Parent	210,000							210,000
Other Comprehensive (Loss)/Income, Net of Tax	$ 2,900					(96)				(96)
Ending balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855					301
Ending balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	1,870,187	$ 0	1,298,134	572,126	(73)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss)/Income	(434,700)					195,659			195,659
Dividends on Common Stock	(942,398)			(942,398)		(112,000)			(112,000)
Capital Contributions from Eversource Parent						400,000		400,000
Other Comprehensive (Loss)/Income, Net of Tax	$ 5,700					73				73
Ending balance (in shares) at Dec. 31, 2023	349,540,266	349,540,266					301
Ending balance at Dec. 31, 2023	$ 14,173,892	$ 1,799,920	$ 8,460,876	$ 4,142,515	$ (33,737)	$ 2,353,919	$ 0	$ 1,698,134	$ 655,785	$ 0

PUBLIC SERVICE COMPANY OF NEW_6

PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	1,305,840	1,194,246	1,103,008
Deferred Income Taxes	85,405	346,779	347,056
Uncollectible Expense	72,468	61,876	60,886
Pension, SERP and PBOP (Income)/Expense, Net	(90,706)	(160,857)	(14,693)
Regulatory Over/(Under) Recoveries, Net	(151,548)	(205,294)	(314,211)
Cost of Removal Expenditures	(315,699)	(303,755)	(242,130)
Other	(53,026)	(39,192)	(64,640)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(124,393)	(470,593)	(135,505)
Taxes Receivable/Accrued, Net	36,357	18,358	(110,621)
Accounts Payable	(287,637)	377,657	(29,201)
Other Current Assets and Liabilities, Net	(66,202)	(45,583)	3,710
Net Cash Flows Provided by Operating Activities	1,646,161	2,401,293	1,962,600
Investing Activities:
Investments in Property, Plant and Equipment	(4,336,849)	(3,441,852)	(3,175,080)
Other Investing Activities	(2,897)	20,420	22,178
Net Cash Flows Used in Investing Activities	(4,870,732)	(4,130,490)	(3,447,374)
Financing Activities:
Cash Dividends on Common Shares	(918,995)	(860,033)	(805,439)
Increase (Decrease) in Notes Payable To Eversource Parent	695,552	(78,170)	256,125
Issuance of Long-Term Debt	5,198,345	4,045,000	3,230,000
Retirement of Long-Term Debt	(2,008,470)	(1,175,000)	(1,142,500)
Repayment of Rate Reduction Bonds	(43,210)	(43,210)	(43,210)
Other Financing Activities	(46,466)	(48,185)	(46,625)
Net Cash Flows Provided by Financing Activities	2,869,237	2,029,941	1,440,832
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(355,334)	300,744	(43,942)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	521,752	221,008	264,950
Cash, Cash Equivalents and Restricted Cash - End of Year	166,418	521,752	221,008
PSNH
Operating Activities:
Net (Loss)/Income	195,659	171,570	150,338
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	140,417	127,962	120,065
Deferred Income Taxes	118,970	15,765	(14,530)
Uncollectible Expense	3,989	9,211	13,113
Pension, SERP and PBOP (Income)/Expense, Net	(10,484)	(16,421)	(3,296)
Regulatory Over/(Under) Recoveries, Net	(273,472)	53,181	32,587
Amortization of Regulatory (Liabilities)/Assets, Net	(16,343)	42,867	86,832
Cost of Removal Expenditures	(39,976)	(39,895)	(30,804)
Other	10,391	8,691	(1,370)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(5,434)	(62,078)	(32,003)
Taxes Receivable/Accrued, Net	916	(23,492)	3,952
Accounts Payable	(55,957)	81,046	(3,256)
Other Current Assets and Liabilities, Net	(36,637)	(6,908)	14,454
Net Cash Flows Provided by Operating Activities	32,039	361,499	336,082
Investing Activities:
Investments in Property, Plant and Equipment	(605,109)	(485,611)	(326,379)
Other Investing Activities	296	1,013	562
Net Cash Flows Used in Investing Activities	(604,813)	(484,598)	(325,817)
Financing Activities:
Cash Dividends on Common Shares	(112,000)	(104,000)	(260,800)
Increase (Decrease) in Notes Payable To Eversource Parent	59,700	62,700	64,300
Issuance of Long-Term Debt	600,000	0	350,000
Retirement of Long-Term Debt	(325,000)	0	(282,000)
Repayment of Rate Reduction Bonds	(43,210)	(43,210)	(43,210)
Capital Contributions from Eversource Parent	400,000	210,000	160,000
Other Financing Activities	(8,524)	(705)	(2,984)
Net Cash Flows Provided by Financing Activities	570,966	124,785	(14,694)
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(1,808)	1,686	(4,429)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	36,812	35,126	39,555
Cash, Cash Equivalents and Restricted Cash - End of Year	$ 35,004	$ 36,812	$ 35,126

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES A. About Eversource, CL&P, NSTAR Electric and PSNH 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, NSTAR Gas and EGMA (natural gas utilities), and Aquarion (water utilities). Eversource provides energy delivery and/or water service to approximately 4.4 million electric, natural gas and water customers through twelve regulated utilities in Connecticut, Massachusetts and New Hampshire. Eversource, CL&P, NSTAR Electric and PSNH are reporting companies under the Securities Exchange Act of 1934. Eversource Energy is a public utility holding company under the Public Utility Holding Company Act of 2005. Arrangements among the regulated electric companies and other Eversource companies, outside agencies and other utilities covering interconnections, interchange of electric power and sales of utility property are subject to regulation by the FERC. Eversource's regulated companies are subject to regulation of rates, accounting and other matters by the FERC and/or applicable state regulatory commissions (the PURA for CL&P, Yankee Gas and Aquarion, the DPU for NSTAR Electric, NSTAR Gas, EGMA and Aquarion, and the NHPUC for PSNH and Aquarion). CL&P, NSTAR Electric and PSNH furnish franchised retail electric service in Connecticut, Massachusetts and New Hampshire, respectively. NSTAR Gas and EGMA are engaged in the distribution and sale of natural gas to customers within Massachusetts and Yankee Gas is engaged in the distribution and sale of natural gas to customers within Connecticut. Aquarion is engaged in the collection, treatment and distribution of water in Connecticut, Massachusetts and New Hampshire. CL&P, NSTAR Electric and PSNH's results include the operations of their respective distribution and transmission businesses. The distribution business also includes the results of NSTAR Electric's solar power facilities. Eversource Service, Eversource's service company, and several wholly-owned real estate subsidiaries of Eversource, provide support services to Eversource, including its regulated companies. B. Basis of Presentation The 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 consolidated financial statements of Eversource, NSTAR Electric and PSNH and the financial statements of CL&P are herein collectively referred to as the "financial statements." 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. CYAPC and YAEC are inactive regional nuclear power companies engaged in the long-term storage of their spent nuclear fuel. Eversource consolidates the operations of 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, including 50 percent ownership interests in three offshore wind projects and a tax equity investment in one of the projects. See Note 6, “Investments in Unconsolidated Affiliates,” for further information on Eversource’s equity method investments and impairment charges recorded in 2023 to the offshore wind investments carrying value. In accordance with accounting guidance on noncontrolling interests in consolidated financial statements, the Preferred Stock of CL&P and the Preferred Stock of NSTAR Electric, which are not owned by Eversource or its consolidated subsidiaries and are not subject to mandatory redemption, have been presented as noncontrolling interests in the financial statements of Eversource. The Preferred Stock of CL&P and the Preferred Stock of NSTAR Electric are considered to be temporary equity and have been classified between liabilities and permanent shareholders' equity on the balance sheets of Eversource, CL&P and NSTAR Electric due to a provision in the preferred stock agreements of both CL&P and NSTAR Electric that grant preferred stockholders the right to elect a majority of the CL&P and NSTAR Electric Boards of Directors, respectively, should certain conditions exist, such as if preferred dividends are in arrears for a specified amount of time. The Net Income reported in the statements of income and cash flows represents net income prior to apportionment to noncontrolling interests, which is represented by dividends on preferred stock of CL&P and NSTAR Electric. 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. As of December 31, 2023 and 2022, Eversource's carrying amount of goodwill was $4.53 billion and $4.52 billion, respectively. Eversource performs an assessment for possible impairment of its goodwill at least annually. Eversource completed its annual goodwill impairment assessment for each of its reporting units as of October 1, 2023 and determined that no impairment exists. See Note 24, "Goodwill," for further information. Certain reclassifications of prior year data were made in the accompanying financial statements to conform to the current year presentation. C. Cash and Cash Equivalents Cash includes cash on hand. At the end of each reporting period, any overdraft amounts are reclassified from Cash to Accounts Payable on the balance sheets. Cash Equivalents include short-term cash investments that are highly liquid in nature and have original maturities of three months or less. D. Allowance for Uncollectible Accounts Receivables, Net on the balance sheets primarily includes 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). The current expected credit loss (CECL) model is 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 an aging-based quantitative assessment that applies an estimated uncollectible percentage to each receivable aging category. Factors in determining credit loss include historical collection, write-off experience, analysis of delinquency statistics, and management's assessment of collectability from customers, including current economic conditions, customer payment trends, the impact on customer bills because of energy usage trends and changes in rates, flexible payment plans and financial hardship arrearage management programs offered to customers, reasonable forecasts, and expectations of future collectability and collection efforts. Management continuously assesses the collectability of receivables and adjusts estimates based on actual experience and future expectations based on economic conditions, collection efforts and other factors. 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. Management concluded that the reserve balance as of December 31, 2023 adequately reflected the collection risk and net realizable value for its receivables. 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, NSTAR Gas and EGMA 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. Management uses a higher credit risk profile for this pool of trade receivables as compared to non-hardship receivables. 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: Eversource CL&P NSTAR Electric PSNH (Millions of Dollars) Hardship Accounts Retail (Non-Hardship), Total Allowance Hardship Accounts Retail (Non-Hardship), Total Allowance Hardship Accounts Retail (Non-Hardship), Total Allowance Total Allowance (2) Balance as of January 1, 2021 $ 194.8 $ 164.1 $ 358.9 $ 129.1 $ 28.3 $ 157.4 $ 39.7 $ 51.9 $ 91.6 $ 17.2 Uncollectible Expense — 60.9 60.9 — 13.5 13.5 — 16.6 16.6 13.1 Uncollectible Costs Deferred (1) 51.9 58.7 110.6 32.3 25.5 57.8 4.3 15.8 20.1 3.1 Write-Offs (22.0) (107.7) (129.7) (18.0) (36.2) (54.2) (0.7) (36.3) (37.0) (10.0) Recoveries Collected 1.4 15.3 16.7 1.2 5.6 6.8 — 5.7 5.7 0.9 Balance as of December 31, 2021 $ 226.1 $ 191.3 $ 417.4 $ 144.6 $ 36.7 $ 181.3 $ 43.3 $ 53.7 $ 97.0 $ 24.3 Uncollectible Expense — 61.9 61.9 — 15.6 15.6 — 21.6 21.6 9.2 Uncollectible Costs Deferred (1) 77.8 34.7 112.5 58.3 1.2 59.5 1.5 10.9 12.4 2.5 Write-Offs (21.3) (102.7) (124.0) (15.3) (23.0) (38.3) (1.1) (41.2) (42.3) (7.7) Recoveries Collected 1.8 16.7 18.5 1.3 5.9 7.2 — 6.3 6.3 0.9 Balance as of December 31, 2022 $ 284.4 $ 201.9 $ 486.3 $ 188.9 $ 36.4 $ 225.3 $ 43.7 $ 51.3 $ 95.0 $ 29.2 Uncollectible Expense — 72.5 72.5 — 11.7 11.7 — 22.8 22.8 4.0 Uncollectible Costs Deferred (1) 137.0 21.2 158.2 114.4 12.0 126.4 1.5 16.0 17.5 (8.7) Write-Offs (55.9) (122.2) (178.1) (44.7) (28.5) (73.2) (1.6) (41.7) (43.3) (10.9) Recoveries Collected 1.3 14.3 15.6 1.1 4.7 5.8 — 5.0 5.0 0.7 Balance as of December 31, 2023 $ 366.8 $ 187.7 $ 554.5 $ 259.7 $ 36.3 $ 296.0 $ 43.6 $ 53.4 $ 97.0 $ 14.3 (1) These expected credit losses are deferred as regulatory costs on the balance sheets, as these amounts are ultimately recovered in rates. Amounts include uncollectible costs for hardship accounts and other customer receivables, including uncollectible amounts related to uncollectible energy supply costs and COVID-19. The increase in the allowance for uncollectible hardship accounts in both 2023 and 2022 at Eversource and CL&P primarily relates to increased customer enrollment in disconnection prevention programs in Connecticut. (2) In connection with PSNH’s pole purchase agreement on May 1, 2023, the purchase price included the forgiveness of previously reserved receivables for reimbursement of operation and maintenance and vegetation management costs. E. Transfer of Energy Efficiency Loans CL&P transferred a portion of its energy efficiency customer loan portfolio to outside lenders in order to make additional loans to customers. CL&P remains the servicer of the loans and will transmit customer payments to the lenders, with a maximum amount outstanding under this program of $55 million. The amounts of the loans are included in Receivables, Net and Other Long-Term Assets, and are offset by Other Current Liabilities and Other Long-Term Liabilities on CL&P’s balance sheet. The current and long-term portions totaled $8.5 million and $14.5 million, respectively, as of December 31, 2023, and $9.1 million and $13.0 million, respectively, as of December 31, 2022. F. Materials, Supplies, Natural Gas and REC Inventory Materials, Supplies, Natural Gas and REC Inventory include materials and supplies purchased primarily for construction or operation and maintenance purposes, natural gas purchased for delivery to customers, and RECs. Inventory is valued at the lower of cost or net realizable value. RECs are purchased from suppliers of renewable sources of generation and are used to meet state mandated Renewable Portfolio Standards requirements. The carrying amounts of materials and supplies, natural gas inventory, and RECs, which are included in Current Assets on the balance sheets, were as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Materials and Supplies $ 397.9 $ 156.2 $ 130.8 $ 76.5 $ 221.0 $ 88.2 $ 81.0 $ 34.4 Natural Gas 65.5 — — — 95.9 — — — RECs 43.9 0.3 43.0 0.6 57.5 — 57.4 0.1 Total $ 507.3 $ 156.5 $ 173.8 $ 77.1 $ 374.4 $ 88.2 $ 138.4 $ 34.5 Fair value measurement guidance is applied to derivative contracts that are not elected or designated as "normal purchases" or "normal sales" (normal) and to 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, equity method investments, AROs, and in the valuation of business combinations and asset acquisitions. The fair value measurement guidance was also applied in estimating the 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 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," Note 6, "Investments in Unconsolidated Affiliates," Note 7, "Asset Retirement Obligations," Note 11A, "Employee Benefits – Pension Benefits and Postretirement Benefits Other Than Pension," Note 15, "Fair Value of Financial Instruments," and Note 24, “Goodwill,” to the financial statements. H. Derivative Accounting Many of the electric and natural gas companies' contracts for the purchase and sale of energy or energy-related products are derivatives. The accounting treatment for energy contracts entered into varies and depends on the intended use of the particular contract and on whether or not the contract is a derivative. The application of derivative accounting is complex and requires management judgment in the following respects: identification of derivatives and embedded derivatives, election and designation of a contract as normal, and determination of the fair value of derivative contracts. All of these judgments can have a significant impact on the financial statements. The judgment applied in the election of a contract as normal (and resulting accrual accounting) includes the conclusion that it is probable at the inception of the contract and throughout its term that it will result in physical delivery of the underlying product and that the quantities will be used or sold by the business in the normal course of business. If facts and circumstances change and management can no longer support this conclusion, then a contract cannot be considered normal, accrual accounting is terminated, and fair value accounting is applied prospectively. The fair value of derivative contracts is based upon the contract terms and conditions and the underlying market price or fair value per unit. When quantities are not specified in the contract, the Company determines whether the contract has a determinable quantity by using amounts referenced in default provisions and other relevant sections of the contract. The fair value of derivative assets and liabilities with the same counterparty are offset and recorded as a net derivative asset or liability on the balance sheets. Regulatory assets or regulatory liabilities are recorded to offset the fair values of these derivative contracts related to energy and energy-related products, as contract settlements are recovered from, or refunded to, customers in future rates. All changes in the fair value of these derivative contracts are recorded as regulatory assets or liabilities and do not impact net income. For further information regarding derivative contracts, see Note 4, "Derivative Instruments," to the financial statements. I. Operating Expenses The cost of natural gas included in Purchased Power, Purchased Natural Gas and Transmission on the statements of income were as follows: For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Eversource - Cost of Natural Gas $ 792.2 $ 1,010.2 $ 718.6 AFUDC represents the cost of borrowed and equity funds used to finance construction and is included in the cost of the electric, natural gas and water companies' utility plant on the balance sheet. The portion of AFUDC attributable to borrowed funds is recorded as a reduction of Interest Expense, and the AFUDC related to equity funds is recorded as Other Income, Net on the statements of income. AFUDC costs are recovered from customers over the service life of the related plant in the form of increased revenue collected as a result of higher depreciation expense. The average AFUDC rate is based on a FERC-prescribed formula using the cost of a company's short-term financings and capitalization (preferred stock, long-term debt and common equity), as appropriate. The average rate is applied to average eligible CWIP amounts to calculate AFUDC. AFUDC costs and the weighted-average AFUDC rates were as follows: Eversource For the Years Ended December 31, (Millions of Dollars, except percentages) 2023 2022 2021 Borrowed Funds $ 44.6 $ 21.8 $ 18.4 Equity Funds 78.1 47.3 37.3 Total AFUDC $ 122.7 $ 69.1 $ 55.7 Average AFUDC Rate 5.8 % 4.7 % 4.2 % For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars, CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Borrowed Funds $ 7.7 $ 17.2 $ 6.1 $ 4.8 $ 10.7 $ 1.4 $ 2.9 $ 9.0 $ 0.8 Equity Funds 20.0 45.7 5.4 13.6 24.6 2.5 7.7 20.4 1.6 Total AFUDC $ 27.7 $ 62.9 $ 11.5 $ 18.4 $ 35.3 $ 3.9 $ 10.6 $ 29.4 $ 2.4 Average AFUDC Rate 6.7 % 5.9 % 5.1 % 6.6 % 5.4 % 2.6 % 5.0 % 4.9 % 2.5 % K. Other Income, Net The components of Other Income, Net on the statements of income were as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion (1) $ 132.9 $ 219.8 $ 84.4 AFUDC Equity 78.1 47.3 37.3 Equity in Earnings of Unconsolidated Affiliates (2) 15.5 22.9 14.2 Investment (Loss)/Income (4.9) 1.9 (0.2) Interest Income 94.2 50.5 25.6 Other (2) 32.3 3.7 — Total Other Income, Net $ 348.1 $ 346.1 $ 161.3 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion (1) $ 34.9 $ 57.4 $ 16.2 $ 64.4 $ 85.5 $ 26.8 $ 15.2 $ 40.2 $ 10.3 AFUDC Equity 20.0 45.7 5.4 13.6 24.6 2.5 7.7 20.4 1.6 Investment (Loss)/Income (2.4) (0.2) (0.7) (1.3) 1.2 0.2 1.3 0.1 0.1 Interest Income 9.0 60.6 5.3 6.5 30.7 3.1 5.9 13.4 2.4 Other 0.1 0.6 0.4 0.1 0.7 0.1 0.1 0.7 0.2 Total Other Income, Net $ 61.6 $ 164.1 $ 26.6 $ 83.3 $ 142.7 $ 32.7 $ 30.2 $ 74.8 $ 14.6 (1) See Note 11A, "Employee Benefits – Pension Benefits and Postretirement Benefits Other Than Pension," for the components of net periodic benefit income/expense for the Pension, SERP and PBOP Plans. The non-service related components of pension, SERP and PBOP benefit income/expense, after capitalization or deferral, are presented as non-operating income and recorded in Other Income, Net on the statements of income. (2) Eversource’s equity method investment in a renewable energy fund was liquidated in March 2023. Liquidation proceeds in excess of the carrying value were recorded in 2023 within Other in the table above. See Note 6, “Investments in Unconsolidated Affiliates,” for further information. For the years ended December 31, 2022 and 2021, pre-tax income of $12.2 million and $2.1 million, respectively, associated with this investment was included in Equity in Earnings of Unconsolidated Affiliates within Other Income, Net in the table above. L. 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 Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Eversource $ 202.9 $ 194.7 $ 181.9 CL&P 174.9 166.1 158.1 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. M. Supplemental Cash Flow Information Eversource (Millions of Dollars) As of and For the Years Ended December 31, 2023 2022 2021 Cash Paid During the Year for: Interest, Net of Amounts Capitalized $ 783.2 $ 636.2 $ 568.7 Income Taxes 39.2 77.9 121.6 Non-Cash Investing Activities: Plant Additions Included in Accounts Payable (As of) 564.1 586.9 467.9 As of and For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Cash Paid/(Received) During the Year for: Interest, Net of Amounts Capitalized $ 176.8 $ 182.8 $ 62.8 $ 167.2 $ 152.8 $ 58.3 $ 161.5 $ 141.6 $ 56.5 Income Taxes (44.1) 31.3 (59.9) 117.6 23.8 58.3 38.4 74.2 51.1 Non-Cash Investing Activities: Plant Additions Included in Accounts 139.8 178.9 65.9 131.8 184.3 76.2 110.6 120.0 68.7 The following table reconciles cash and cash equivalents as reported on the balance sheets to the cash, cash equivalents and restricted cash balance as reported on the statements of cash flows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Cash and Cash Equivalents as reported on the $ 53.9 $ 10.2 $ 6.7 $ 0.2 $ 374.6 $ 11.3 $ 327.7 $ 0.1 Restricted cash included in: Special Deposits 81.5 2.0 16.1 31.6 102.2 8.8 17.5 33.1 Marketable Securities 13.7 — — — 25.4 0.2 0.1 0.4 Other Long-Term Assets 17.3 — — 3.2 19.6 — — 3.2 Cash, Cash Equivalents and Restricted Cash $ 166.4 $ 12.2 $ 22.8 $ 35.0 $ 521.8 $ 20.3 $ 345.3 $ 36.8 Special Deposits represent cash collections related to the PSNH RRB customer charges that are held in trust, required ISO-NE cash deposits, cash held in escrow accounts, and CYAPC and YAEC cash balances. Special Deposits are included in Current Assets on the balance sheets. As of both December 31, 2023 and December 31, 2022, restricted cash included in Marketable Securities represented money market funds held in restricted trusts to fund CYAPC and YAEC's spent nuclear fuel storage obligations. As of December 31, 2022, restricted cash included in Marketable Securities also included money market funds held in trusts to fund certain non-qualified executive benefits. Eversource’s restricted cash includes an Energy Relief Fund for energy efficiency and clean energy measures in the Merrimack Valley established under the terms of the EGMA 2020 settlement agreement. This restricted cash held in escrow accounts included $20.0 million recorded as short-term in Special Deposits as of both December 31, 2023 and December 31, 2022, and $14.1 million and $15.9 million recorded in Other Long-Term Assets on the balance sheets as of December 31, 2023 and December 31, 2022, respectively. N. Related Parties Eversource Service, Eversource's service company, provides centralized accounting, administrative, engineering, financial, information technology, legal, operational, planning, purchasing, tax, and other services to Eversource's companies. The Rocky River Realty Company and Properties, Inc., two other Eversource subsidiaries, construct, acquire or lease some of the property and facilities used by Eversource's companies. As of December 31, 2022, CL&P, NSTAR Electric and PSNH had long-term receivables from Eversource Service in the amounts of $25.0 million, $5.5 million and $3.8 million, which were included in Other Long-Term Assets on the balance sheets. These amounts related to the funding of investments held in trust by Eversource Service in connection with certain postretirement benefits for CL&P, NSTAR Electric and PSNH employees and were eliminated in consolidation on the Eversource financial statements. As of December 31, 2023, these intercompany balances were settled. Included in the CL&P, NSTAR Electric and PSNH balance sheets as of December 31, 2023 and 2022 were Accounts Receivable from Affiliated Companies and Accounts Payable to Affiliated Companies relating to transactions between CL&P, NSTAR Electric and PSNH and other subsidiaries that are wholly-owned by Eversource. These amounts have been eliminated in consolidation on the Eversource financial statements. The Eversource Energy Foundation is an independent not-for-profit charitable entity and is not included in the consolidated financial statements of Eversource as the Company does not have title to, and cannot receive contributions back from, the Eversource Energy Foundation's assets. Eversource made contributions to the Eversource Energy Foundation of $20.0 million in 2023 and $8.0 million in 2022, and did not make any contributions in 2021.

REGULATORY ACCOUNTING

REGULATORY ACCOUNTING	12 Months Ended
	Dec. 31, 2023
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 and the regulatory assets that have been recorded. If management were to determine that it could no longer apply the accounting guidance applicable to rate-regulated enterprises, or if management could not conclude it is probable that costs would be recovered from customers in future rates, the applicable 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 December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Storm Costs, Net $ 1,785.9 $ 896.6 $ 609.1 $ 280.2 $ 1,379.1 $ 799.3 $ 484.4 $ 95.4 Regulatory Tracking Mechanisms 1,319.2 354.5 482.9 182.2 1,075.3 216.8 391.5 73.7 Benefit Costs 1,117.3 197.4 336.7 79.3 921.7 156.7 299.5 56.6 Income Taxes, Net 912.4 512.6 128.6 16.4 853.3 491.1 115.6 16.0 Securitized Stranded Costs 392.5 — — 392.5 435.7 — — 435.7 Goodwill-related 264.1 — 226.7 — 281.0 — 241.2 — Asset Retirement Obligations 137.9 38.5 72.3 4.7 127.9 35.9 68.2 4.4 Derivative Liabilities 120.9 120.9 — — 181.8 181.8 — — Other Regulatory Assets 339.0 22.7 101.6 8.0 322.5 26.2 114.0 14.4 Total Regulatory Assets 6,389.2 2,143.2 1,957.9 963.3 5,578.3 1,907.8 1,714.4 696.2 Less: Current Portion 1,674.2 480.4 676.1 189.5 1,335.5 314.1 492.8 102.2 Total Long-Term Regulatory Assets $ 4,715.0 $ 1,662.8 $ 1,281.8 $ 773.8 $ 4,242.8 $ 1,593.7 $ 1,221.6 $ 594.0 Storm Costs, Net: The storm cost deferrals relate to costs incurred for storm events at CL&P, NSTAR Electric and PSNH that each company expects to recover from customers. A storm must meet certain criteria to qualify for deferral and recovery with the criteria specific to each state jurisdiction and utility company. Once a storm qualifies for recovery, all qualifying expenses incurred during storm restoration efforts are deferred and recovered from customers. Costs for storms that do not meet the specific criteria are expensed as incurred. In addition to storm restoration costs, CL&P and PSNH are each allowed to recover pre-staging storm costs. Management believes all storm costs deferred were prudently incurred and meet the criteria for specific cost recovery in Connecticut, Massachusetts and New Hampshire, and that recovery from customers is probable through the applicable regulatory recovery processes. Each electric utility company either recovers a carrying charge on its deferred storm cost regulatory asset balance or the regulatory asset balance is included in rate base. Multiple tropical and severe storms over the past several years have caused extensive damage to Eversource’s electric distribution systems resulting in significant numbers and durations of customer outages, along with significant pre-staging costs. Storms in 2023 that qualified for future recovery resulted in deferred storm restoration costs and pre-staging costs totaling $542 million at Eversource, including $178 million at CL&P, $192 million at NSTAR Electric, and $172 million at PSNH. Management believes that all of these storm costs were prudently incurred and meet the criteria for specific cost recovery. Of Eversource’s total deferred storm costs, $1.75 billion either have yet to be filed with the applicable regulatory commission, are pending regulatory approval, or are subject to prudency review (including $975 million at CL&P, $526 million at NSTAR Electric and $246 million at PSNH) as of December 31, 2023. These storm cost totals exclude storm funding amounts that are collected in rates, which are recorded as a reduction to the deferred storm cost regulatory asset balance. CL&P, NSTAR Electric and PSNH are seeking approval of their deferred storm restoration costs through the applicable regulatory recovery process. As part of CL&P’s October 1, 2021 settlement agreement, CL&P agreed to freeze its current base distribution rates (including storm costs) until no earlier than January 1, 2024. On December 22, 2023, CL&P initiated a docket seeking a prudency review of approximately $634 million of catastrophic storm costs for twenty-four weather events from January 1, 2018 to December 31, 2021. In the filing, CL&P requested PURA establish a rate to collect $50 million annually from customers from the date of the final decision in this proceeding. This rate would be effective until the next distribution rate case and would replenish the under-collected storm reserve and reduce future carrying charges for customers. CL&P’s storm events include the August 4, 2020 Tropical Storm Isaias, which resulted in deferred storm restoration costs of approximately $232 million at CL&P as of December 31, 2023. Although in 2021 PURA found that CL&P’s performance in its preparation for, and response to, Tropical Storm Isaias fell below applicable performance standards in certain instances, CL&P believes it presented in its 2023 storm filing, credible evidence demonstrating there is no reasonably close causal connection between the alleged sub-standard performance and the storm costs incurred. While it is possible that some amount of storm costs may be disallowed by PURA, any such amount cannot be estimated at this time. CL&P continues to believe that these storm restoration costs associated with Tropical Storm Isaias were prudently incurred and meet the criteria for cost recovery; and as a result, management does not expect the storm cost review by PURA to have a material impact on the financial position or results of operations of CL&P. Regulatory Tracking Mechanisms: The regulated companies' approved rates are designed to recover costs incurred to provide service to customers. The regulated companies recover certain of their costs on a fully-reconciling basis through regulatory commission-approved tracking mechanisms. The differences between the costs incurred (or the rate recovery allowed) and the actual revenues are recorded as regulatory assets (for undercollections) or as regulatory liabilities (for overcollections) to be included in future customer rates each year. Carrying charges are recovered in rates on all material regulatory tracking mechanisms. The electric and natural gas distribution companies recover, on a fully reconciling basis, the costs associated with the procurement of energy and natural gas supply, electric transmission related costs from FERC-approved transmission tariffs, energy efficiency programs, low income assistance programs, certain uncollectible accounts receivable for hardship customers, restructuring and stranded costs as a result of deregulation (including securitized RRB charges), certain capital tracking mechanisms for infrastructure improvements, and additionally for the Massachusetts utilities, pension and PBOP benefits, net metering for distributed generation, and solar-related programs. CL&P, NSTAR Electric, Yankee Gas, NSTAR Gas, EGMA and the Aquarion Water Company of Connecticut each have a regulatory commission approved revenue decoupling mechanism. Distribution revenues are decoupled from customer sales volumes, where applicable, which breaks the relationship between sales volumes and revenues. Each company reconciles its annual base distribution rate recovery amount to the pre-established levels of baseline distribution delivery service revenues. Any difference between the allowed level of distribution revenue and the actual amount realized during a 12-month period is adjusted through rates in the following period. Benefit Costs: Deferred benefit costs represent unrecognized actuarial losses and gains and unrecognized prior service costs and credits attributable to Eversource's Pension, SERP and PBOP Plans. The regulated companies record actuarial losses and gains and prior service costs and credits arising at the December 31st remeasurement date of the funded status of the benefit plans as a regulatory asset or regulatory liability in lieu of a charge to Accumulated Other Comprehensive Income/(Loss), reflecting ultimate recovery from customers through rates. The regulatory asset or regulatory liability is amortized with the recognition of actuarial losses and gains and prior service costs and credits to net periodic benefit expense/income over the estimated average future employee service period using the corridor approach. Regulatory accounting is also applied to the portions of Eversource's service company costs that support the regulated companies, as these amounts are also recoverable. As these regulatory assets or regulatory liabilities do not represent a cash outlay for the regulated companies, no carrying charge is recovered from customers. See Note 11A, "Employee Benefits - Pension Benefits and Postretirement Benefits Other Than Pension," for further information on regulatory benefit plan amounts arising and amortized during the year. Eversource, CL&P, NSTAR Electric, and PSNH recover benefit costs related to their distribution and transmission operations from customers in rates as allowed by their applicable regulatory commissions. NSTAR Electric, NSTAR Gas and EGMA recover qualified pension and PBOP expenses related to their distribution operations through a rate reconciling mechanism that fully tracks the change in net pension and PBOP expenses each year. The electric transmission companies' rates provide for an annual true-up of estimated to actual costs, which include pension and PBOP expenses. Income Taxes, Net: The tax effect of temporary book-tax differences (differences between the periods in which transactions affect income in the financial statements and the periods in which they affect the determination of taxable income, including those differences relating to uncertain tax positions) is accounted for in accordance with the rate-making treatment of the applicable regulatory commissions and accounting guidance for income taxes. Differences in income taxes between the accounting guidance and the rate-making treatment of the applicable regulatory commissions are recorded as regulatory assets. As these assets are offset by deferred income tax liabilities, no carrying charge is collected. The amortization period of these assets varies depending on the nature and/or remaining life of the underlying assets and liabilities. For further information regarding income taxes, see Note 12, "Income Taxes," to the financial statements. Securitized Stranded Costs: In 2018, a subsidiary of PSNH issued $635.7 million of securitized RRBs to finance PSNH's unrecovered remaining costs associated with the divestiture of its generation assets. Securitized regulatory assets, which are not earning an equity return, are being recovered over the amortization period of the associated RRBs. The PSNH RRBs are expected to be repaid by February 1, 2033. For further information, see Note 10, "Rate Reduction Bonds and Variable Interest Entities," to the financial statements. Goodwill-related: The goodwill regulatory asset originated from a 1999 transaction, and the DPU allowed its recovery in NSTAR Electric and NSTAR Gas rates. This regulatory asset is currently being amortized and recovered from customers in rates without a carrying charge over a 40-year period, and as of December 31, 2023, there were 16 years of amortization remaining. Asset Retirement Obligations: The costs associated with the depreciation of the regulated companies' ARO assets and accretion of the ARO liabilities are recorded as regulatory assets in accordance with regulatory accounting guidance. The regulated companies' ARO assets, regulatory assets, and ARO liabilities offset and are excluded from rate base. These costs are being recovered over the life of the underlying property, plant and equipment. Derivative Liabilities: Regulatory assets are recorded as an offset to derivative liabilities and relate to the fair value of contracts used to purchase energy and energy-related products that will be recovered from customers in future rates. These assets are excluded from rate base and are being recovered as the actual settlements occur over the duration of the contracts. See Note 4, "Derivative Instruments," to the financial statements for further information on these contracts. Other Regulatory Assets: Other Regulatory Assets primarily include environmental remediation costs, certain uncollectible accounts receivable for hardship customers, certain exogenous property taxes and merger-related costs allowed for recovery, contractual obligations associated with the spent nuclear fuel storage costs of the CYAPC, YAEC and MYAPC decommissioned nuclear power facilities, water tank painting costs, losses associated with the reacquisition or redemption of long-term debt, removal costs incurred that exceed amounts collected from customers, and various other items. Regulatory Costs in Other Long-Term Assets: Eversource's regulated companies had $241.7 million (including $166.7 million for CL&P, $21.9 million for NSTAR Electric and $1.2 million for PSNH) and $210.8 million (including $135.9 million for CL&P, $19.8 million for NSTAR Electric and $1.0 million for PSNH) of additional regulatory costs not yet specifically approved as of December 31, 2023 and 2022, respectively, that were included in Other Long-Term Assets on the balance sheets. These amounts will be reclassified to Regulatory Assets upon approval by the applicable regulatory agency. 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. As of December 31, 2023 and 2022, these regulatory costs included $82.1 million (including $64.0 million for CL&P and $7.3 million for NSTAR Electric) and $64.0 million (including $52.8 million for CL&P and $3.5 million for NSTAR Electric), respectively, of deferred uncollectible hardship costs. Equity Return on Regulatory Assets: For rate-making purposes, the regulated companies recover the carrying costs related to their regulatory assets. For certain regulatory assets, the carrying cost recovered includes an equity return component. This equity return is not recorded on the balance sheets. The equity return for PSNH was $10.2 million and $4.1 million as of December 31, 2023 and 2022, respectively. These carrying costs will be recovered from customers in future rates. Regulatory Liabilities: The components of regulatory liabilities were as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH EDIT due to Tax Cuts and Jobs Act of 2017 $ 2,548.6 $ 969.2 $ 905.1 $ 339.3 $ 2,619.3 $ 983.6 $ 944.3 $ 348.6 Cost of Removal 666.6 157.9 420.9 16.2 670.6 130.8 405.3 14.7 Regulatory Tracking Mechanisms 668.3 154.0 347.2 114.4 890.8 361.0 336.1 155.0 Deferred Portion of Non-Service Income 354.0 49.9 175.9 36.6 270.9 34.5 139.7 28.8 AFUDC - Transmission 124.3 56.1 68.2 — 98.2 48.2 50.0 — Benefit Costs 51.0 0.6 22.2 — 55.4 0.7 31.4 — Other Regulatory Liabilities 201.9 30.4 13.9 4.6 215.9 40.6 14.5 6.5 Total Regulatory Liabilities 4,614.7 1,418.1 1,953.4 511.1 4,821.1 1,599.4 1,921.3 553.6 Less: Current Portion 591.8 102.2 368.1 117.5 890.8 336.0 373.2 162.0 Total Long-Term Regulatory Liabilities $ 4,022.9 $ 1,315.9 $ 1,585.3 $ 393.6 $ 3,930.3 $ 1,263.4 $ 1,548.1 $ 391.6 EDIT due to Tax Cuts and Jobs Act of 2017: Pursuant to the Tax Cuts and Jobs Act of 2017, Eversource had remeasured its existing deferred federal income tax balances to reflect the decrease in the U.S. federal corporate income tax rate from 35 percent to 21 percent. The remeasurement resulted in provisional regulated excess accumulated deferred income tax (excess ADIT or EDIT) liabilities that will benefit customers in future periods and were recognized as regulatory liabilities on the balance sheet. EDIT liabilities related to property, plant, and equipment are subject to IRS normalization rules and will be returned to customers using the same timing as the remaining useful lives of the underlying assets that gave rise to the ADIT liabilities. Eversource's regulated companies (except for the Connecticut water business) are in the process of refunding the EDIT liabilities to customers based on orders issued by applicable state and federal regulatory commissions. Cost of Removal: Eversource's regulated companies currently recover amounts in rates for future costs of removal of plant assets over the lives of the assets. The estimated cost to remove utility assets from service is recognized as a component of depreciation expense, and the cumulative amount collected from customers but not yet expended is recognized as a regulatory liability. Expended removal costs that exceed amounts collected from customers are recognized as regulatory assets, as they are probable of recovery in future rates. Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP: Regulatory liabilities were recorded for the deferred portion of the non-service related components of net periodic benefit expense/(income) for the Pension, SERP and PBOP Plans. These regulatory liabilities will be amortized over the remaining useful lives of the various classes of utility property, plant and equipment. AFUDC - Transmission: Regulatory liabilities were recorded by CL&P and NSTAR Electric for AFUDC accrued on certain reliability-related transmission projects to reflect local rate base recovery. These regulatory liabilities will be amortized over the depreciable life of the related transmission assets. Other Regulatory Liabilities: Other Regulatory Liabilities primarily include EGMA’s acquired regulatory liability as a result of the 2020 DPU-approved rate settlement agreement and the CMA asset acquisition on October 9, 2020, and various other items. FERC ROE Complaints: As of December 31, 2023 and 2022, Eversource has a reserve established for the second ROE complaint period in the pending FERC ROE complaint proceedings, which was recorded as a regulatory liability and is reflected within Regulatory Tracking Mechanisms in the table above. The cumulative pre-tax reserve (excluding interest) as of December 31, 2023 and 2022 totaled $39.1 million for Eversource (including $21.4 million for CL&P, $14.6 million for NSTAR Electric and $3.1 million for PSNH). See Note 13E, "Commitments and Contingencies – FERC ROE Complaints," for further information on developments in the pending ROE complaint proceedings. Regulatory Developments: 2022 CL&P Rate Relief Plan: On November 28, 2022, Governor Lamont, DEEP, Office of Consumer Counsel, and CL&P jointly developed a rate relief plan for electric customers for the winter peak season of January 1, 2023 through April 30, 2023. On December 16, 2022, PURA approved the rate relief plan. As part of the rate relief plan, CL&P reduced the Non-Bypassable Federally Mandated Congestion Charge (NBFMCC) rate effective January 1, 2023 to provide customers with an average $10 monthly bill credit from January through April 2023. This rate reduction accelerated the return to customers of net revenues generated by long-term state-approved energy contracts with the Millstone and Seabrook nuclear power plants of approximately $90 million. The rate relief plan also included instituting a temporary, flat monthly discount for qualifying low-income hardship customers effective January 1, 2023. This flat-rate credit will continue until a new low-income discount rate that was approved by PURA in an October 19, 2022 decision is implemented in 2024. These aspects of the rate relief plan do not impact CL&P’s earnings but do impact its future cash flows. Also as part of the rate relief plan, CL&P committed to contribute $10 million to an energy assistance program for qualifying hardship customers, which was distributed as a bill credit to those customers during 2023. CL&P recorded a current liability of $10 million on the balance sheet and a charge to expense on the statement of income for the year ended December 31, 2022 associated with the customer assistance program. 2022 NSTAR Electric Distribution Rate Case : On November 30, 2022, the DPU issued its decision in the NSTAR Electric distribution rate case and approved a base distribution rate increase of $64 million effective January 1, 2023. The DPU approved a renewal of the PBR plan originally authorized in its previous rate case for a five-year term, with a corresponding stay out provision. The PBR plan term has the possibility of a five-year extension. The PBR mechanism allows for an annual adjustment to base distribution rates for inflation and exogenous events. The DPU also allowed for adjustments to the PBR mechanism for the recovery of future capital additions based on a historical five-year average of total capital additions, beginning with the January 1, 2024 PBR adjustment. The decision allows an authorized regulatory ROE of 9.80 percent on a capital structure including 53.2 percent equity. Among other items, the DPU approved an increase to the annual storm fund contribution collected through base distribution rates from $10 million to $31 million, and allowed for the recovery of storm threshold costs of $1.3 million per storm event subsequent to the eighth storm in a calendar year (six recovered in base rates plus two additional storms). The DPU approved cost recovery of a portion of NSTAR Electric’s outstanding storm costs beginning on January 1, 2023 and January 1, 2024, subject to reconciliation from future prudency reviews. In a subsequent compliance filing, the DPU allowed recovery to commence for outstanding storm costs occurring between 2018 and 2022 and interest in a total of $162.1 million over a five-year period starting January 1, 2023. In addition, NSTAR Electric will begin to recover 2021 exogenous storms and interest in a total of $220.9 million over a five-year period beginning January 1, 2024. The DPU also approved the recovery of historical exogenous property taxes of $30.8 million incurred from 2020 through 2022 over a two-year period and $8.3 million incurred from 2012 through 2015 over a five-year period effective January 1, 2023. As a result of this decision, these deferred property taxes were reclassified from Other Long-Term Assets to Regulatory Assets on the NSTAR Electric December 31, 2022 balance sheet. 2023 NSTAR Electric Distribution Rates : NSTAR Electric submitted its first annual PBR Adjustment filing on September 15, 2023 and on December 26, 2023, the DPU approved a $104.9 million increase to base distribution rates effective January 1, 2024. The base distribution rate increase was comprised of a $50.6 million inflation-based adjustment and a $54.3 million K-bar adjustment for capital additions based on the difference between the historical five-year average of total capital additions and the base capital revenue requirement. 2022 NSTAR Gas Distribution Rates: NSTAR Gas’ PBR mechanism allows for an annual adjustment to base distribution rates for inflation and exogenous events. NSTAR Gas submitted its second annual PBR Adjustment filing on September 15, 2022 and on October 31, 2022, the DPU approved a $21.7 million increase to base distribution rates for effect on November 1, 2022. The increase is inclusive of a $4.5 million permanent increase related to exogenous property taxes and a $5.4 million increase related to an October 6, 2021 mitigation plan filing that delayed recovery of a portion of a base distribution rate increase originally scheduled to take effect November 1, 2021. The DPU also approved the recovery of historical exogenous property taxes incurred from November 1, 2020 through October 31, 2022 of $8.2 million over a two-year period through a separate reconciling mechanism effective November 1, 2022. As a result of this decision, these deferred property taxes were reclassified from Other Long-Term Assets to Regulatory Assets on the Eversource December 31, 2022 balance sheet. 2023 NSTAR Gas Distribution Rates: NSTAR Gas submitted its third annual PBR Adjustment filing on September 15, 2023 and on October 30, 2023, the DPU approved a $25.4 million increase to base distribution rates, of which, $15.5 million was associated with a base rate adjustment and the remainder for a prior period exogenous cost adjustment, for effect on November 1, 2023. 2022 EGMA Distribution Rates: As established in an October 7, 2020 EGMA Rate Settlement Agreement approved by the DPU, on September 16, 2022 EGMA filed for its second base distribution rate increase and on October 31, 2022, the DPU approved a $6.7 million increase to base distribution rates and a $3.3 million increase to the Tax Act Credit Factor for effect on November 1, 2022. The DPU also approved the recovery of historical exogenous property taxes incurred from November 1, 2020 through October 31, 2022 of $8.6 million over a two-year period through a separate reconciling mechanism effective November 1, 2022. EGMA will request recovery of incremental property taxes incurred after October 31, 2022 in future exogenous filings. As a result of this decision, these deferred property taxes were reclassified from Other Long-Term Assets to Regulatory Assets on the Eversource December 31, 2022 balance sheet. 2023 PSNH Pole Acquisition Approval: On November 18, 2022, the NHPUC issued a decision that approved a proposed purchase agreement between PSNH and Consolidated Communications, in which, PSNH would acquire both jointly-owned and solely-owned poles and pole assets. The NHPUC also authorized PSNH to recover certain expenses associated with the operation and maintenance of the transferred poles, pole inspections, and vegetation management expenses through a new cost recovery mechanism, the Pole Plant Adjustment Mechanism (PPAM), subject to consummation of the purchase agreement. The purchase agreement was finalized on May 1, 2023 for a purchase price of $23.3 million. Upon consummation of the purchase agreement, PSNH established a regulatory asset of $16.9 million for operation and maintenance expenses and vegetation management expenses associated with the purchased poles incurred from February 10, 2021 through April 30, 2023 that PSNH is authorized to collect through the PPAM regulatory tracking mechanism. The establishment of the PPAM regulatory asset resulted in a pre-tax benefit recorded in Amortization expense on the PSNH statement of income in 2023.

PROPERTY, PLANT AND EQUIPMENT A

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION	PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION Utility property, plant and equipment is recorded at original cost. Original cost includes materials, labor, construction overheads and AFUDC for regulated property. The cost of repairs and maintenance is charged to Operations and Maintenance expense as incurred. The following tables summarize property, plant and equipment by asset category: Eversource As of December 31, (Millions of Dollars) 2023 2022 Distribution - Electric $ 19,656.5 $ 18,326.2 Distribution - Natural Gas 8,155.3 7,443.8 Transmission - Electric 14,666.8 13,709.3 Distribution - Water 2,280.1 2,112.6 Solar 201.1 200.8 Utility 44,959.8 41,792.7 Other (1) 2,006.8 1,738.1 Property, Plant and Equipment, Gross 46,966.6 43,530.8 Less: Accumulated Depreciation Utility (9,670.1) (9,167.4) Other (869.6) (706.1) Total Accumulated Depreciation (10,539.7) (9,873.5) Property, Plant and Equipment, Net 36,426.9 33,657.3 Construction Work in Progress 3,071.7 2,455.5 Total Property, Plant and Equipment, Net $ 39,498.6 $ 36,112.8 As of December 31, 2023 2022 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH Distribution - Electric $ 7,897.1 $ 9,000.5 $ 2,799.2 $ 7,370.1 $ 8,410.0 $ 2,586.4 Transmission - Electric 6,548.2 5,630.8 2,489.5 6,165.1 5,333.8 2,212.0 Solar — 201.1 — — 200.8 — Property, Plant and Equipment, Gross 14,445.3 14,832.4 5,288.7 13,535.2 13,944.6 4,798.4 Less: Accumulated Depreciation (2,670.5) (3,585.9) (984.0) (2,567.1) (3,381.2) (912.3) Property, Plant and Equipment, Net 11,774.8 11,246.5 4,304.7 10,968.1 10,563.4 3,886.1 Construction Work in Progress 565.4 1,507.3 270.0 498.9 1,063.6 174.1 Total Property, Plant and Equipment, Net $ 12,340.2 $ 12,753.8 $ 4,574.7 $ 11,467.0 $ 11,627.0 $ 4,060.2 (1) These assets are primarily comprised of computer software, hardware and equipment at Eversource Service and buildings at The Rocky River Realty Company. Depreciation: Depreciation of utility assets is calculated on a straight-line basis using composite rates based on the estimated remaining useful lives of the various classes of property (estimated useful life for PSNH distribution and the water utilities). The composite rates, which are subject to approval by the appropriate state regulatory agency, include a cost of removal component, which is collected from customers over the lives of the plant assets and is recognized as a regulatory liability. Depreciation rates are applied to property from the time it is placed in service. Upon retirement from service, the cost of the utility asset is charged to the accumulated provision for depreciation. The actual incurred removal costs are applied against the related regulatory liability. The depreciation rates for the various classes of utility property, plant and equipment aggregate to composite rates as follows: (Percent) 2023 2022 2021 Eversource 3.1 % 3.0 % 3.1 % CL&P 2.8 % 2.8 % 2.8 % NSTAR Electric 2.7 % 2.7 % 2.8 % PSNH 3.0 % 3.0 % 3.1 % The following table summarizes average remaining useful lives of depreciable assets: As of December 31, 2023 (Years) Eversource CL&P NSTAR Electric PSNH Distribution - Electric 34.0 35.3 34.5 29.6 Distribution - Natural Gas 35.7 — — — Transmission - Electric 40.6 37.1 45.3 41.4 Distribution - Water 40.0 — — — Solar 22.8 — 22.8 — Other (1) 10.4 — — — (1) The estimated useful life of computer software, hardware and equipment primarily ranges from 5 to 15 years and of buildings is 40 years.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	12 Months Ended
	Dec. 31, 2023
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 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 December 31, 2023 2022 CL&P (Millions of Dollars) Fair Value Hierarchy Commodity Supply Netting (1) Net Amount Fair Value Hierarchy Commodity Supply Netting (1) Net Amount Current Derivative Assets Level 2 $ 16.4 $ (0.5) $ 15.9 Level 3 $ 16.3 $ (0.5) $ 15.8 Long-Term Derivative Assets Level 2 13.6 (0.5) 13.1 Level 3 28.8 (0.9) 27.9 Current Derivative Liabilities Level 2 (81.9) — (81.9) Level 3 (81.6) — (81.6) Long-Term Derivative Liabilities Level 2 (68.0) — (68.0) Level 3 (143.9) — (143.9) (1) Amounts represent derivative assets and liabilities that Eversource elected to record net on the balance sheets. These amounts are subject to master netting agreements or similar agreements for which the right of offset exists. The business activities that result in the recognition of derivative assets also create exposure to various counterparties. As of December 31, 2023, CL&P's derivative assets were exposed to counterparty credit risk and contracted with investment grade entities. 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 December 31, 2023 and 2022 were 682 MW and 674 MW, respectively. 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. For the years ended December 31, 2023, 2022 and 2021, there were losses of $3.9 million, gains of $10.1 million and losses of $7.1 million, respectively, deferred as regulatory costs, which reflect the change in fair value associated with Eversource's derivative contracts. Fair Value Measurements of Derivative Instruments The fair value of derivative contracts utilizes both observable and unobservable inputs. The fair value is modeled using income techniques, such as discounted cash flow valuations adjusted for assumptions related to exit price. Valuations of derivative contracts using a discounted cash flow methodology include assumptions regarding the timing and likelihood of scheduled capacity 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. Significant observable inputs for valuations of these contracts include energy-related product prices in future years for which quoted prices in an active market exist. 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. Fair value measurements were prepared by individuals with expertise in valuation techniques, pricing of energy-related products, and accounting requirements. All derivative contracts were classified as Level 2 in the fair value hierarchy as of December 31, 2023, and were classified as Level 3 as of December 31, 2022. Exit price premiums are unobservable inputs 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. As of December 31, 2022, these exit price premiums were a Level 3 significant unobservable input and ranged from 2.9 percent through 7.1 percent, or a weighted average of 6.1 percent. As of December 31, 2023, exit price premiums are no longer considered significant in the valuation of the derivative contracts. As of December 31, 2022, Level 3 significant unobservable inputs also utilized in the valuation of CL&P’s capacity-related contracts included forward reserve prices of $0.44 per kW-Month through $0.50 per kW-Month, or a weighted average of $0.47 per kW-Month, over the period 2023 through 2024. As of December 31, 2023, these forward reserve price inputs are now observable. 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. 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 (Millions of Dollars) For the Years Ended December 31, 2023 2022 Derivatives, Net: Fair Value as of Beginning of Period $ (181.8) $ (249.2) Net Realized/Unrealized (Losses)/Gains Included in Regulatory Assets (3.9) 10.1 Settlements 64.8 57.3 Transfers out of Level 3 (1) 120.9 — Fair Value as of End of Period $ — $ (181.8) (1) Transfers out of Level 3 pertain to certain significant valuation inputs becoming observable as well as certain unobservable inputs no longer being significant to the fair value of the derivative contracts. Eversource's policy is to recognize transfers between levels of the fair value hierarchy as of the end of the reporting period.

MARKETABLE SECURITIES

MARKETABLE SECURITIES	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
MARKETABLE SECURITIES	MARKETABLE SECURITIES Eversource’s marketable securities include the CYAPC and YAEC legally restricted trusts that each hold equity and available-for-sale debt securities to fund the spent nuclear fuel removal obligations of their nuclear fuel storage facilities. Eversource also holds trusts that are not subject to regulatory oversight by state or federal agencies that are primarily used to fund certain non-qualified executive benefits. The marketable securities within these non-qualified executive benefit trusts were sold in 2023. Equity and available-for-sale debt marketable securities are recorded at fair value, with the current portion recorded in Prepayments and Other Current Assets and the long-term portion recorded in Marketable Securities on the balance sheets. Equity Securities: Unrealized gains and losses on equity securities held in Eversource's trusts are recorded in Other Income, Net on the statements of income. The fair value of these equity securities as of December 31, 2023 and 2022 was $3.3 million and $20.0 million, respectively. Eversource’s non-qualified executive benefits equity securities were sold during 2023 and resulted in a $1.1 million gain recorded in Other Income, Net for the year ended December 31, 2023. For the years ended December 31, 2022 and 2021, there were unrealized losses of $9.7 million and unrealized gains of $4.4 million recorded in Other Income, Net related to these equity securities, respectively. Eversource's equity securities also include CYAPC's and YAEC's marketable securities held in spent nuclear fuel trusts, which had fair values of $173.6 million and $170.1 million as of December 31, 2023 and 2022, respectively. Unrealized gains and losses for these spent nuclear fuel trusts are subject to regulatory accounting treatment and are recorded in long-term Marketable Securities with the corresponding offset to 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: As of December 31, 2023 2022 Eversource (Millions of Dollars) Amortized Pre-Tax Pre-Tax Fair Value Amortized Pre-Tax Pre-Tax Fair Value Debt Securities $ 169.5 $ 1.4 $ (6.6) $ 164.3 $ 201.6 $ 0.1 $ (16.2) $ 185.5 Unrealized gains and losses on available-for-sale debt securities held in Eversource's non-qualified executive 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. These debt securities were sold during 2023 and resulted in $1.2 million of realized losses for the year ended December 31, 2023 that were reclassified out of Accumulated Other Comprehensive Income and recorded in Other Income, Net. There were no credit losses for the years ended December 31, 2023 and 2022, and no allowance for credit losses as of December 31, 2023. 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 were investment-grade bonds with a lower default risk based on their credit quality. Eversource's debt securities also include CYAPC's and YAEC's marketable securities held in spent nuclear fuel trusts in the amounts of $164.3 million and $163.2 million as of December 31, 2023 and 2022, respectively. Unrealized gains and losses for available-for-sale debt securities included in the CYAPC and YAEC spent nuclear fuel trusts are subject to regulatory accounting treatment and are recorded in Marketable Securities with the corresponding offset to long-term liabilities on the balance sheets, with no impact on the statements of income. Pre-tax unrealized gains and losses as of December 31, 2023 and 2022 primarily relate to the debt securities included in CYAPC's and YAEC's spent nuclear fuel trusts. CYAPC and YAEC’s spent nuclear fuel trusts are restricted and are classified in long-term Marketable Securities on the balance sheets. As of December 31, 2023, the contractual maturities of available-for-sale debt securities were as follows: Eversource (Millions of Dollars) Amortized Fair Less than one year $ 15.9 $ 15.9 One to five years 30.9 30.9 Six to ten years 38.1 37.8 Greater than ten years 84.6 79.7 Total Debt Securities $ 169.5 $ 164.3 Realized Gains and Losses: Realized gains and losses are recorded in Other Income, Net for Eversource's benefit trust and are offset in 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 December 31, 2023 2022 Level 1: Mutual Funds and Equities $ 176.9 $ 190.1 Money Market Funds 13.7 25.4 Total Level 1 $ 190.6 $ 215.5 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 90.1 $ 82.3 Corporate Debt Securities 34.0 46.1 Asset-Backed Debt Securities 5.6 8.6 Municipal Bonds 9.8 12.7 Other Fixed Income Securities 11.1 10.4 Total Level 2 $ 150.6 $ 160.1 Total Marketable Securities $ 341.2 $ 375.6 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.

INVESTMENTS IN UNCONSOLIDATED A

INVESTMENTS IN UNCONSOLIDATED AFFILIATES	12 Months Ended
	Dec. 31, 2023
Equity Method Investments and Joint Ventures [Abstract]
INVESTMENTS IN UNCONSOLIDATED AFFILIATES	INVESTMENTS IN UNCONSOLIDATED AFFILIATES Investments in entities that are not consolidated are included in long-term assets on the balance sheets and earnings impacts from these equity investments are included in Other Income, Net on the statements of income. Eversource's investments included the following: Investment Balance as of December 31, (Millions of Dollars) Ownership Interest 2023 2022 Offshore Wind Business 50% - 100% $ 515.5 $ 1,947.1 Natural Gas Pipeline - Algonquin Gas Transmission, LLC 15% 116.0 118.8 Renewable Energy Investment Fund 90% — 84.1 Other various 29.0 26.1 Total Investments in Unconsolidated Affiliates $ 660.5 $ 2,176.1 For the years ended December 31, 2023, 2022 and 2021, Eversource had equity in earnings of unconsolidated affiliates of $15.5 million, $22.9 million, and $14.2 million, respectively. Eversource received dividends from its equity method investees (excluding proceeds received from sale or liquidation of investments) of $20.1 million, $26.2 million, and $21.6 million, respectively, for the years ended December 31, 2023, 2022 and 2021. Investments in affiliates where Eversource has the ability to exercise significant influence, but not control, over an investee are initially recognized as an equity method investment at cost. Eversource’s offshore wind investments, which include 50 percent ownership interests in two offshore wind joint ventures and a 100 percent ownership in a tax equity investment, do not represent controlling financial interests. Eversource’s offshore wind investments, its share of the natural gas pipeline and other investments included in the table above are accounted for under the equity method. Offshore Wind Business: Eversource’s offshore wind business includes 50 percent ownership interests in each of North East Offshore and South Fork Class B Member, LLC, which collectively hold three offshore wind projects. North East Offshore holds the Revolution Wind project and the Sunrise Wind project. South Fork Class B Member, LLC holds the South Fork Wind project. Eversource’s offshore wind business also includes a noncontrolling tax equity investment in South Fork Wind through a 100 percent ownership in South Fork Wind Holdings, LLC Class A shares. The offshore wind projects are being developed and constructed through joint and equal partnerships with Ørsted. Expected Sales of Offshore Wind Investments : On May 25, 2023, Eversource announced that it had completed a strategic review of its offshore wind investments and determined that it would pursue the sale of its offshore wind investments. On September 7, 2023, Eversource completed the sale of its 50 percent interest in an uncommitted lease area consisting of approximately 175,000 developable acres located 25 miles off the south coast of Massachusetts to Ørsted for $625 million in an all-cash transaction. In September of 2023, Eversource made a contribution of $528 million using the proceeds from the lease area sale to invest in a tax equity interest for South Fork Wind. South Fork Wind was restructured as a tax equity investment, with Eversource purchasing 100 percent ownership of a new Class A tax equity membership interest. As a result of this investment, Eversource expects to receive investment tax credits after the turbines are placed in service for South Fork Wind and meet the requirements to qualify for the ITC. These credits will be utilized to reduce Eversource’s federal tax liability or generate tax refunds over the next 24 months. All of South Fork Wind’s twelve turbines are expected to be installed and placed into service by the end of March 2024. On January 24, 2024, Ørsted signed an agreement with Eversource to acquire Eversource’s 50 percent share of Sunrise Wind. The sale is subject to the successful selection of Sunrise Wind in the ongoing New York fourth solicitation for offshore wind capacity, signing of an OREC contract with NYSERDA, finalization of sale agreements, receipt of final federal construction permits, and relevant regulatory approvals. If Sunrise Wind is not successful in the solicitation, then the existing OREC contract for Sunrise Wind will be cancelled according to the state’s requirements, and Eversource and Ørsted’s joint venture for Sunrise Wind will remain in place. In that scenario, Ørsted and Eversource would then assess their options in determining the best path forward for Sunrise Wind and its assets, which include the BOEM offshore lease area. If Sunrise Wind’s revised bid is successful in the new solicitation, Sunrise Wind would have 90 days to negotiate a new OREC agreement at the re-bid price. In a successful re-bid, Ørsted would become the sole owner of Sunrise Wind, while Eversource would remain contracted to lead the project’s onshore construction. If Sunrise Wind is successful in the re-bid, Ørsted would pay Eversource 50 percent of the negotiated purchase price upon closing the sale transaction, with the remaining 50 percent paid when onshore construction is completed and certain other milestones are achieved. On January 25, 2024, Eversource and Ørsted submitted a new proposal for Sunrise Wind in the New York fourth offshore wind solicitation. On February 13, 2024, Eversource announced that it has executed an agreement to sell its existing 50 percent interests in the South Fork Wind and Revolution Wind projects to Global Infrastructure Partners (GIP). As part of this transaction, Eversource expects to receive approximately $1.1 billion of cash proceeds upon closing, which includes the sales value related to the 10 percent energy community ITC adder of approximately $170 million related to Revolution Wind, and to exit these projects while retaining certain cost sharing obligations for the construction of Revolution Wind. The purchase price is subject to future post-closing adjustment payments based on, among other things, the progress, timing and expense of construction at each project. The cost sharing obligations provide that Eversource would share equally with GIP in GIP’s funding obligations for up to approximately $240 million of incremental capital expenditure overruns incurred during the construction phase for the Revolution Wind project, after which GIP’s obligations for any additional capital expenditure overruns would be shared equally by Eversource and Ørsted. Additionally, Eversource’s financial exposure will be adjusted by certain purchase price adjustments to be made following commercial operation of the Revolution Wind project and closing of South Fork as a result of final project economics, which includes Eversource’s obligation to maintain GIP’s internal rate of return for each project as specified in the agreement. Eversource currently expects that South Fork Wind will reach full commercial operation prior to closing of the sale with GIP and Eversource does not expect any material cost sharing or other purchase price adjustment payments for South Fork Wind. Factors that could result in Eversource’s total net proceeds from the transaction to be lower or higher include Revolution Wind’s eligibility for federal investment tax credits at other than the anticipated 40 percent level; the ultimate cost of construction and extent of cost overruns for Revolution Wind; delays in constructing Revolution Wind, which would impact the economics associated with the purchase price adjustment; and a benefit due to Eversource if there are lower operation costs or higher availability of the projects through the period that is four years following the commercial operation date of the Revolution Wind project. Closing a transaction with GIP would be subject to customary conditions, including certain regulatory approvals under the Hart Scott Rodino Act and by the New York Public Service Commission and the FERC, as well as other conditions, among which is the completion and execution of the partnership agreements between GIP and Ørsted that will govern GIP’s new ownership interest in those projects following Eversource’s divestiture. Closing of the transaction is currently expected to occur in mid-2024. If closing of the sale is delayed, additional capital contributions made by Eversource would be recovered in the sales price. Under the agreement, Eversource’s existing credit support obligations are expected to roll off for each project around the time that each project completes its expected capital spend. Impairment: Equity method investments are assessed for impairment when conditions exist as of the balance sheet date that indicate that the fair value of the investment may be less than book value. Eversource continually monitors and evaluates its equity method investments to determine if there are indicators of an other-than-temporary impairment. If the decline in value is considered to be other-than-temporary, the investment is written down to its estimated fair value, which establishes a new cost basis in the investment. Subsequent declines or recoveries after the reporting date are not considered in the impairment recognized. Investments that are other-than-temporarily impaired and written down to their estimated fair value cannot subsequently be written back up for increases in estimated fair value. Impairment evaluations involve a significant degree of judgment and estimation, including identifying circumstances that indicate an impairment may exist at the equity method investment level, selecting discount rates used to determine fair values, and developing an estimate of discounted future cash flows expected from investment operations or the sale of the investment. In connection with the process to divest its offshore wind business, Eversource identified indicators for impairment in both the second and fourth quarters of 2023. In each impairment assessment, Eversource evaluated its investments and determined that the carrying value of the equity method offshore wind investments exceeded the fair value of the investments and that the decline in fair value was other-than-temporary. The completion of the strategic review in the second quarter of 2023 resulted in Eversource recording a pre-tax other-than-temporary impairment charge of $401 million ($331 million after-tax) to reflect the investment at estimated fair value based on the expected sales price at that time. This established a new cost basis in the investments. Negative developments in the fourth quarter of 2023, including a lower expected sales price, additional projected construction cost increases, and the October 2023 OREC pricing denial for Sunrise Wind, resulted in Eversource conducting an impairment evaluation and recognizing an additional pre-tax other-than-temporary impairment charge of $1.77 billion ($1.62 billion after-tax) and establishing a new cost basis in the investments as of December 31, 2023. The Eversource statement of income reflects a total pre-tax other-than-temporary impairment charge of $2.17 billion ($1.95 billion after-tax) in its offshore wind investments for the year ended 2023. The impairment evaluations involved judgments in developing the estimates and timing of the future cash flows arising from the expected sales price of Eversource’s 50 percent interest in the wind projects, including expected sales value from investment tax credit adder amounts, less estimated costs to sell, and uncertainties related to the Sunrise Wind re-bid process in New York’s offshore wind solicitation. Additional assumptions in the fourth quarter assessment included revised projected construction costs and estimated project cost overruns, estimated termination costs, salvage values of Sunrise Wind assets, and the value of the tax equity ownership interest. The assumptions used in the discounted cash flow analyses are subject to inherent uncertainties and subjectivity. The use of different assumptions, estimates, or judgments with respect to the estimation of future cash flows could materially change the impairment charges. The impairment evaluations were based on best information available at the impairment assessment dates. New information from events or circumstances arising after the balance sheet date, such as the January 25, 2024 re-bid of Sunrise Wind in the New York solicitation, are not included in the December 31, 2023 impairment evaluation. All significant inputs into the impairment evaluations were Level 3 fair value measurements. The expected cash flows arising from the anticipated sales are a significant input in the impairment evaluation. In the fourth quarter of 2023, project construction forecasts were updated, and these new forecasts reflected additional expenditures for construction and scheduling related pressures, including the availability and increased cost of installation vessels and supply chain cost increases related to foundation fabrication. In determining the current fair value of the investments, these updated projections exceeded the previously estimated projections for construction expenditures, which resulted in a revised sales price that was significantly lower than the previous bid value. Another significant assumption in the impairment evaluation includes the probability of payment of future cost overruns on the three wind projects through each project's respective commercial operation date, which would not be recovered in the expected sales price. This assumption was based on construction projections updated in the fourth quarter of 2023 exceeding prior estimates. An increase in expected cost overruns could result in a significant impairment in a future period. Another key assumption in the impairment model of our offshore wind investments was investment tax credit (“ITC”) adders that were included in the Inflation Reduction Act and were a separate part of the sales price value offered by GIP. An ITC adder is an additional 10 percent of credit value for ITC eligible costs and include two distinct qualifications related to either using domestic sourced materials (domestic content) or construction of an onshore substation in a designated community (energy community). Similar to the base ITC of 30 percent of the eligible costs, any ITC adders generated would be used to reduce an owner’s federal tax liability and could be used to receive tax refunds from prior years as well. Management believes there is a high likelihood that the 10 percent energy community ITC adder is realizable, and that ITC adder would amount to approximately $170 million of additional sales value related to Revolution Wind and that it would qualify for the ITC adder after it reaches commercial operation in 2025. Although management believes the ITC adder value is realizable, there is some uncertainty at this time as to whether or not those ITC adders can be achieved, and management continues to evaluate the project’s qualifications and to monitor guidance issued by the United States Treasury Department. A change in the expected value or qualification of ITC adders could result in a significant impairment in a future period. Another fourth quarter 2023 development included in the impairment evaluation is the key judgment regarding the probability of future cash inflows and outflows associated with the sale or abandonment of the Sunrise Wind project and the expected outcome of the New York fourth offshore wind solicitation in 2024. In June 2023, Sunrise Wind filed a petition with the New York State Public Service Commission for an order authorizing NYSERDA to amend the Sunrise Wind OREC contract to increase the contract price to cover increased costs and inflation. At that time, management expected the contract repricing would be successful given NYSERDA’s public support for pricing adjustments. On October 12, 2023, the New York State Public Service Commission denied this petition. Subsequent to the denial, on November 30, 2023, the general terms of an expedited offshore wind renewable energy solicitation in New York were released. A primary condition for Sunrise Wind to participate in this new solicitation was to agree to terminate its existing OREC agreement. As of December 31, 2023, Eversource and Ørsted were considering whether to submit a new bid for Sunrise Wind, the price at which a new bid would be made, and the probability of success in the new bidding process. The December 31, 2023 impairment evaluation included management’s judgment of the likelihood of possible future scenarios that included the Sunrise Wind project continuing with its existing OREC contract, the project re-bidding and being selected in the new solicitation, the project re-bidding and not being selected, or the project not moving forward. The unfavorable development of the October 2023 denial of the OREC pricing petition, management’s assessment of the likelihood of success in the competitive New York re-bidding process, and the increased costs to build the project, have resulted in management’s assumption that the Sunrise Wind project will ultimately be abandoned, and therefore, no sales value was modeled in the impairment evaluation. Additionally, in the abandonment assumption, management has assumed the loss of contingent sales value associated with any related ITC adders and has estimated future cash outflows for Eversource’s share of cancellation costs required under Sunrise Wind’s supplier contracts, partially offset by expected salvage value and expected cost overruns not incurred in the case of abandonment that are included in the fourth quarter 2023 impairment charge. An increase in expected cancellation costs could result in a significant impairment in a future period. A summary of the significant estimates and assumptions included in the 2023 impairment charges is as follows: Second Quarter 2023 Fourth Quarter 2023 Total (Millions of Dollars) Lower expected sales proceeds across all three wind projects $ 401 $ 525 $ 926 Expected cost overruns not recovered in the sales price — 441 441 Loss of sales value from the sale price offered by GIP, including loss of ITC adders value, cancellation costs and other impacts assuming Sunrise Wind project is abandoned — 800 800 Impairment Charges, pre-tax 401 1,766 2,167 Tax Benefit (70) (144) (214) Impairment Charges, after-tax $ 331 $ 1,622 1,953 A summary of the carrying value by investee and by project as of December 31, 2023 is as follows: Investments Expected to be Disposed of Investment to be Held North East Offshore South Fork Class B Member, LLC South Fork Wind Holdings, LLC Class A Total Offshore Wind Investments (Millions of Dollars) Sunrise Wind Revolution Wind Carrying Value as of December 31, 2023, before $ 699 $ 799 $ 299 $ 485 $ 2,282 Fourth Quarter 2023 Impairment Charge (1,218) (544) — (4) (1,766) Carrying Value as of December 31, 2023 $ (519) $ 255 $ 299 $ 481 $ 516 Management will continue to monitor and evaluate all facts and circumstances in the offshore wind sales process and the impact on its investment balance. Adverse changes in facts and circumstances of estimates and timing of future cash flows and the factors described above could result in the recognition of additional, significant impairment charges that could be material to the financial statements. The impairment charge was a non-cash charge and did not impact Eversource’s cash position. Eversource will continue to make future cash expenditures for required cash contributions to its offshore wind investments up to the time of disposition of each of the offshore wind projects. Capital contributions are expected until the sales are completed and changes in the timing and amounts of these contributions would be adjusted in the sales prices and therefore not result in an additional impairment charge. Proceeds from the transactions will be used to pay off parent company debt. Eversource’s offshore wind investments do not meet the criteria to qualify for presentation as a discontinued operation. Capital contributions in the offshore wind investments, including the 2023 contribution for the tax equity investment in South Fork Wind, are included in Investments in Unconsolidated Affiliates on the statements of cash flows. Proceeds received from the 2023 sale of the uncommitted lease area and from an October 2023 distribution of $318 million received primarily as a result of being a 50 percent joint owner in the Class B shares of South Fork Wind which was restructured as a tax equity investment, are included in Proceeds from Unconsolidated Affiliates on the statement of cash flows. As of December 31, 2023, Eversource’s share of underlying equity in net assets of the offshore wind business exceeded the carrying amount of the offshore wind investments as a result of the 2023 impairments. As of December 31, 2022, the carrying amount of Eversource’s offshore wind investments exceeded its share of underlying equity in net assets by $343.1 million. The basis differences as of December 31, 2022 were primarily comprised of $168.9 million of equity method goodwill that was not being amortized, intangible assets for PPAs, and capitalized interest. Liquidation of Renewable Energy Investment Fund: On March 21, 2023, Eversource’s equity method investment in a renewable energy investment fund was liquidated by the fund’s general partner in accordance with the partnership agreement. Proceeds received from the liquidation totaled $147.6 million and are included in Proceeds from Unconsolidated Affiliates on the statement of cash flows for the year ended December 31, 2023. A portion of the proceeds was used to make a charitable contribution to the Eversource Energy Foundation (a related party) of $20.0 million in 2023. The liquidation benefit received in excess of the investment’s carrying value and the charitable contribution are included in Other Income, Net on the statement of income. NSTAR Electric: As of December 31, 2023 and 2022, NSTAR Electric's investments included a 14.5 percent ownership interest in two companies that transmit hydro-electricity imported from the Hydro-Quebec system in Canada of $9.6 million and $9.3 million, respectively.

ASSET RETIREMENT OBLIGATIONS

ASSET RETIREMENT OBLIGATIONS	12 Months Ended
	Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract]
ASSET RETIREMENT OBLIGATIONS	ASSET RETIREMENT OBLIGATIONS Eversource, including CL&P, NSTAR Electric and PSNH, recognizes a liability for the fair value of an ARO on the obligation date if the liability's fair value can be reasonably estimated, even if it is conditional on a future event. Settlement dates and future costs are reasonably estimated when sufficient information becomes available. Management has identified various categories of AROs, primarily CYAPC's and YAEC's obligation to dispose of spent nuclear fuel and high level waste, and also certain assets containing asbestos and hazardous contamination. Management has performed fair value calculations reflecting expected probabilities for settlement scenarios. The fair value of an ARO is recorded as a long-term liability with a corresponding amount included in Property, Plant and Equipment, Net on the balance sheets. The ARO assets are depreciated, and the ARO liabilities are accreted over the estimated life of the obligation and the corresponding credits are recorded as accumulated depreciation and ARO liabilities, respectively. As the electric and natural gas companies are rate-regulated on a cost-of-service basis, these companies apply regulatory accounting guidance and both the depreciation and accretion costs associated with these companies' AROs are recorded as increases to Regulatory Assets on the balance sheets. A reconciliation of the beginning and ending carrying amounts of ARO liabilities is as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Balance as of Beginning of Year $ 502.7 $ 37.4 $ 101.3 $ 4.9 $ 500.1 $ 35.0 $ 97.5 $ 4.7 Liabilities Settled During the Year (24.9) — — — (22.3) — — — Accretion 29.2 2.5 4.3 0.3 28.9 2.4 4.1 0.2 Revisions in Estimated Cash Flows (1.2) — (0.8) — (4.0) — (0.3) — Balance as of End of Year $ 505.8 $ 39.9 $ 104.8 $ 5.2 $ 502.7 $ 37.4 $ 101.3 $ 4.9 Eversource's amounts include CYAPC and YAEC's AROs of $315.8 million and $320.5 million as of December 31, 2023 and 2022, respectively. The fair value of the ARO for CYAPC and YAEC includes uncertainties of the fuel off-load dates related to the DOE's timing of performance regarding its obligation to dispose of the spent nuclear fuel and high level waste and other assumptions, including discount rates. The incremental asset recorded as an offset to the ARO liability was fully depreciated since the plants have no remaining useful life. Any changes in the ARO liability are recorded with a corresponding offset to the related regulatory asset. The assets held in the CYAPC and YAEC spent nuclear fuel trusts are restricted for settling the ARO and all other nuclear fuel storage obligations. For further information on the assets held in the spent nuclear fuel trusts, see Note 5, "Marketable Securities," to the financial statements.

SHORT-TERM DEBT

SHORT-TERM DEBT	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
SHORT-TERM DEBT	SHORT-TERM DEBT Short-Term Debt - Borrowing Limits: The amount of short-term borrowings that may be incurred by CL&P and NSTAR Electric is subject to periodic approval by the FERC. Because the NHPUC has jurisdiction over PSNH's short-term debt, PSNH is not currently required to obtain FERC approval for its short-term borrowings. On November 30, 2023, the FERC granted authorization that allows CL&P to issue total short-term borrowings in an aggregate principal amount not to exceed $600 million outstanding at any one time, through December 31, 2025. On December 18, 2023, the FERC granted authorization that allows NSTAR Electric to issue total short-term borrowings in an aggregate principal amount not to exceed $655 million outstanding at any one time, through December 31, 2025. PSNH is authorized by regulation of the NHPUC to incur short-term borrowings up to 10 percent of net fixed plant plus an additional $60 million until further ordered by the NHPUC. As of December 31, 2023, PSNH's short-term debt authorization under the 10 percent of net fixed plant test plus $60 million totaled $483.2 million. CL&P's certificate of incorporation contains preferred stock provisions restricting the amount of unsecured debt that CL&P may incur, including limiting unsecured indebtedness with a maturity of less than 10 years to 10 percent of total capitalization. As of December 31, 2023, CL&P had $625.7 million of unsecured debt capacity available under this authorization. Yankee Gas, NSTAR Gas and EGMA are not required to obtain approval from any state or federal authority to incur short-term debt. Short-Term Debt - Commercial Paper Programs and Credit Agreements : Eversource parent has a $2.00 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, EGMA and Aquarion Water Company of Connecticut are parties to a five-year $2.00 billion revolving credit facility, which terminates on October 13, 2028. This re volving credit facility serves to backstop Eversource parent's $2.00 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 October 13, 2028, and 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 Available Borrowing Capacity as of December 31, Weighted-Average Interest Rate as of December 31, (Millions of Dollars) 2023 2022 2023 2022 2023 2022 Eversource Parent Commercial Paper Program $ 1,771.9 $ 1,442.2 $ 228.1 $ 557.8 5.60 % 4.63 % NSTAR Electric Commercial Paper Program 365.8 — 284.2 650.0 5.40 % — % There were no borrowings outstanding on the revolving credit facilities as of December 31, 2023 or 2022. CL&P and PSNH have uncommitted line of credit agreements totaling $375 million and $250 million, respectively, which will expire in 2024. There are no borrowings outstanding on either the CL&P or PSNH uncommitted line of credit agreements as of December 31, 2023. Amounts outstanding under the commercial paper programs 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 CL&P long-term debt issuance in January 2024, $207.3 million of commercial paper borrowings under the Eversource parent commercial paper program were reclassified as Long-Term Debt on Eversource parent’s balance sheet as of December 31, 2023. Under the credit facilities described above, Eversource and its subsidiaries, including CL&P, NSTAR Electric, PSNH, NSTAR Gas, EGMA, Yankee Gas, and Aquarion Water Company of Connecticut, must comply with certain financial and non-financial covenants, including a consolidated debt to total capitalization ratio. As of December 31, 2023 and 2022, Eversource and its subsidiaries were in compliance with these covenants. If Eversource or its subsidiaries were not in compliance with these covenants, an event of default would occur requiring all outstanding borrowings by such borrower to be repaid, and additional borrowings by such borrower would not be permitted under its respective credit facility. 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 December 31, 2023, there were intercompany loans from Eversource parent to CL&P of $457.0 million and to PSNH of $233.0 million. As of December 31, 2022, there were intercompany loans from Eversource parent to PSNH of $173.3 million. Eversource parent charges interest on these intercompany loans at the same weighted-average interest rate as its commercial paper program. 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, as these intercompany borrowings are outstanding for no more than 364 days at one time. As a result of the CL&P long-term debt issuance in January 2024, $207.3 million of CL&P’s intercompany borrowings were reclassified to Long-Term Debt on CL&P’s balance sheet as of December 31, 2023. Sources and Uses of Cash

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Details of long-term debt outstanding are as follows: CL&P (Millions of Dollars) As of December 31, Interest Rate 2023 2022 First Mortgage Bonds: 1994 Series D due 2024 7.875 % $ 139.8 $ 139.8 2004 Series B due 2034 5.750 % 130.0 130.0 2005 Series B due 2035 5.625 % 100.0 100.0 2006 Series A due 2036 6.350 % 250.0 250.0 2007 Series B due 2037 5.750 % 150.0 150.0 2007 Series D due 2037 6.375 % 100.0 100.0 2013 Series A due 2023 2.500 % — 400.0 2014 Series A due 2044 4.300 % 475.0 475.0 2015 Series A due 2045 4.150 % 350.0 350.0 2017 Series A due 2027 3.200 % 500.0 500.0 2018 Series A due 2048 4.000 % 800.0 800.0 2020 Series A due 2025 0.750 % 400.0 400.0 2021 Series A due 2031 2.050 % 425.0 425.0 2023 Series A due 2053 5.250 % 500.0 — 2023 Series B due 2033 4.900 % 300.0 — Total First Mortgage Bonds 4,619.8 4,219.8 Less Amounts due Within One Year (139.8) (400.0) Current Portion Classified as Long-Term Debt (1) 139.8 400.0 Commercial Paper Classified as Long-Term Debt (See Note 8, Short-Term Debt) 207.3 — Unamortized Premiums and Discounts, Net 18.0 21.5 Unamortized Debt Issuance Costs (30.7) (24.8) CL&P Long-Term Debt $ 4,814.4 $ 4,216.5 NSTAR Electric (Millions of Dollars) As of December 31, Interest Rate 2023 2022 Debentures: 2006 Debentures due 2036 5.750 % $ 200.0 $ 200.0 2010 Debentures due 2040 5.500 % 300.0 300.0 2014 Debentures due 2044 4.400 % 300.0 300.0 2015 Debentures due 2025 3.250 % 250.0 250.0 2016 Debentures due 2026 2.700 % 250.0 250.0 2017 Debentures due 2027 3.200 % 700.0 700.0 2019 Debentures due 2029 3.250 % 400.0 400.0 2020 Debentures due 2030 3.950 % 400.0 400.0 2021 Debentures due 2051 3.100 % 300.0 300.0 2021 Debentures due 2031 1.950 % 300.0 300.0 2022 Debentures due 2052 4.550 % 450.0 450.0 2022 Debentures due 2052 4.950 % 400.0 400.0 2023 Debentures due 2028 5.600 % 150.0 — Total Debentures 4,400.0 4,250.0 Notes: 2004 Senior Notes Series B due 2034 5.900 % 50.0 50.0 2007 Senior Notes Series D due 2037 6.700 % 40.0 40.0 2013 Senior Notes Series G due 2023 3.880 % — 80.0 2016 Senior Notes Series H due 2026 2.750 % 50.0 50.0 Total Notes 140.0 220.0 Less Amounts due Within One Year — (80.0) Unamortized Premiums and Discounts, Net (14.0) (14.8) Unamortized Debt Issuance Costs (29.1) (30.1) NSTAR Electric Long-Term Debt $ 4,496.9 $ 4,345.1 PSNH (Millions of Dollars) As of December 31, Interest Rate 2023 2022 First Mortgage Bonds: 2005 Series M due 2035 5.600 % $ 50.0 $ 50.0 2013 Series S due 2023 3.500 % — 325.0 2019 Series T due 2049 3.600 % 300.0 300.0 2020 Series U due 2050 2.400 % 150.0 150.0 2021 Series V due 2031 2.200 % 350.0 350.0 2023 Series W due 2053 5.150 % 300.0 — 2023 Series X due 2033 5.350 % 300.0 — Total First Mortgage Bonds 1,450.0 1,175.0 Less Amounts due Within One Year — (325.0) Current Portion Classified as Long-Term Debt (1) — 295.3 Unamortized Premiums and Discounts, Net (4.9) (2.5) Unamortized Debt Issuance Costs (13.5) (7.9) PSNH Long-Term Debt $ 1,431.6 $ 1,134.9 OTHER (Millions of Dollars) As of December 31, Interest Rate 2023 2022 Eversource Parent - Senior Notes due 2024 - 2050 0.800 % - 5.950% $ 10,300.0 $ 8,150.0 Yankee Gas - First Mortgage Bonds due 2024 - 2051 1.380 % - 5.510% 1,015.0 845.0 NSTAR Gas - First Mortgage Bonds due 2025 - 2051 2.250 % - 7.110% 705.0 705.0 EGMA - First Mortgage Bonds due 2028 - 2052 2.110 % - 5.730% 708.0 650.0 Aquarion - Senior Notes due 2024 4.000% 360.0 360.0 Aquarion - Unsecured Notes due 2028 - 2052 3.000 % - 6.430% 527.0 464.7 Aquarion - Secured Debt due 2027 - 2044 1.550 % - 9.290% 39.0 34.4 Pre-1983 Spent Nuclear Fuel Obligation (CYAPC) 12.5 11.9 Fair Value Adjustment (2) 19.3 26.2 Less Fair Value Adjustment - Current Portion (2) (5.5) (7.0) Less Amounts due in One Year (1,810.2) (1,203.4) Current Portion Classified as Long-Term Debt (1) 990.9 — Unamortized Premiums and Discounts, Net 49.7 40.1 Unamortized Debt Issuance Costs (65.0) (49.4) Total Other Long-Term Debt $ 12,845.7 $ 10,027.5 Total Eversource Long-Term Debt $ 23,588.6 $ 19,724.0 (1) As a result of the CL&P and Eversource parent long-term debt issuances in January 2024, $139.8 million and $990.9 million, respectively, of current portion of long-term debt were reclassified as Long-Term Debt on CL&P’s and Eversource parent’s balance sheets as of December 31, 2023. As a result of the CL&P and PSNH long-term debt issuances in January 2023, $400 million and $295.3 million, respectively, of current portion of long-term debt were reclassified as Long-Term Debt on CL&P’s and PSNH’s balance sheets as of December 31, 2022. (2) The fair value adjustment amount is the purchase price adjustments, net of amortization, required to record long-term debt at fair value on the dates of the 2012 merger with NSTAR and the 2017 acquisition of Aquarion. Availability under Long-Term Debt Issuance Authorizations: On June 14, 2022, the DPU approved NSTAR Gas’ request for authorization to issue up to $325 million in long-term debt through December 31, 2024. On November 30, 2022, the PURA approved CL&P's request for authorization to issue up to $1.15 billion in long-term debt through December 31, 2024. As a result of CL&P’s January 2024 long-term debt issuance, CL&P has now fully utilized this authorization. On June 7, 2023, PURA approved Yankee Gas’ request for authorization to issue up to $350 million in long-term debt through December 31, 2024. On November 21, 2023, NSTAR Electric petitioned the DPU requesting authorization to issue up to $2.4 billion in long-term debt through December 31, 2026. On February 8, 2024, the NHPUC approved PSNH’s request for authorization to issue up to $300 million in long-term debt through December 31, 2024. Long-Term Debt Issuances and Repayments: The following table summarizes long-term debt issuances and repayments: (Millions of Dollars) Interest Rate Issuance/ Issue Date or Repayment Date Maturity Date Use of Proceeds for Issuance/ CL&P 2023 Series A First Mortgage Bonds 5.25 % $ 500.0 January 2023 January 2053 Repaid 2013 Series A Bonds at maturity and short-term debt, and paid capital expenditures and working capital CL&P 2013 Series A First Mortgage Bonds 2.50 % (400.0) January 2023 January 2023 Paid at maturity CL&P 2023 Series B First Mortgage Bonds 4.90 % 300.0 July 2023 July 2033 Repaid short-term debt, paid capital expenditures and working capital CL&P 2024 Series A First Mortgage Bonds 4.65 % 350.0 January 2024 January 2029 Repaid short-term debt, paid capital expenditures and working capital NSTAR Electric 2023 Debentures 5.60 % 150.0 September 2023 October 2028 Repaid Series G Senior Notes at maturity and short-term debt and for general corporate purposes NSTAR Electric 2013 Series G Senior Notes 3.88 % (80.0) November 2023 November 2023 Paid at maturity PSNH Series W First Mortgage Bonds 5.15 % 300.0 January 2023 January 2053 Repaid short-term debt, paid capital expenditures and working capital PSNH Series X First Mortgage Bonds 5.35 % 300.0 September 2023 October 2033 Repaid Series S Bonds at maturity and for general corporate purposes PSNH Series S First Mortgage Bonds 3.50 % (325.0) November 2023 November 2023 Paid at maturity Eversource Parent Series Z Senior Notes 5.45 % 750.0 March 2023 March 2028 Repaid Series F Senior Notes at maturity and short-term debt Eversource Parent Series F Senior Notes 2.80 % (450.0) May 2023 May 2023 Paid at maturity Eversource Parent Series Z Senior Notes 5.45 % 550.0 May 2023 March 2028 Repaid Series T Senior Notes and Series N Senior Notes at maturity and short-term debt Eversource Parent Series AA Senior Notes 4.75 % 450.0 May 2023 May 2026 Repaid Series T Senior Notes and Series N Senior Notes at maturity and short-term debt Eversource Parent Series BB Senior Notes 5.125 % 800.0 May 2023 May 2033 Repaid Series T Senior Notes and Series N Senior Notes at maturity and short-term debt Eversource Parent Variable Rate Series T Senior Notes SOFR plus 0.25% (350.0) August 2023 August 2023 Paid at maturity Eversource Parent Series CC Senior Notes 5.95 % 800.0 November 2023 February 2029 Repaid Series N Senior Notes at maturity and short-term debt Eversource Parent Series N Senior Notes 3.80 % (400.0) December 2023 December 2023 Paid at maturity Eversource Parent Series DD Senior Notes 5.00 % 350.0 January 2024 January 2027 Repaid short-term debt Eversource Parent Series EE Senior Notes 5.50 % 650.0 January 2024 January 2034 Repaid short-term debt Yankee Gas Series V First Mortgage Bonds 5.51 % 170.0 August 2023 August 2030 Repaid short-term debt and general corporate purposes EGMA Series D First Mortgage Bonds 5.73 % 58.0 November 2023 November 2028 Repaid short-term debt, paid capital expenditures and working capital Aquarion Water Company of Connecticut Senior Notes 5.89 % 50.0 September 2023 October 2043 Repaid existing indebtedness, paid capital expenditures and general corporate purposes Long-Term Debt Provisions: The utility plant of CL&P, PSNH, Yankee Gas, NSTAR Gas, EGMA and a portion of Aquarion is subject to the lien of each company's respective first mortgage bond indenture. The Eversource parent, NSTAR Electric and a portion of Aquarion debt is unsecured. Additionally, the long-term debt agreements provide that Eversource and certain of its subsidiaries must comply with certain covenants as are customarily included in such agreements, including equity requirements for NSTAR Electric, NSTAR Gas and Aquarion. Under the equity requirements, NSTAR Electric's and Aquarion's senior notes must maintain a certain consolidated indebtedness to capitalization ratio as of the end of any fiscal quarter and NSTAR Gas' outstanding long-term debt must not exceed equity. Certain secured and unsecured long-term debt securities are callable at redemption price or are subject to make-whole provisions. No long-term debt defaults have occurred as of December 31, 2023. CYAPC's Pre-1983 Spent Nuclear Fuel Obligation: Under the Nuclear Waste Policy Act of 1982, the DOE is responsible for the selection and development of repositories for, and the disposal of, spent nuclear fuel and high-level radioactive waste. CYAPC is obligated to pay the DOE for the costs to dispose of spent nuclear fuel and high-level radioactive waste generated prior to April 7, 1983 (pre-1983 Spent Nuclear Fuel). CYAPC has partially paid this obligation and recorded an accrual for its remaining liability to the DOE. This liability accrues interest costs at the 3-month Treasury bill yield rate. For nuclear fuel used to generate electricity prior to April 7, 1983, payment may be made any time prior to the first delivery of spent fuel to the DOE. As of December 31, 2023 and 2022, as a result of consolidating CYAPC, Eversource has consolidated $12.5 million and $11.9 million, respectively, in pre-1983 spent nuclear fuel obligations to the DOE. The obligation includes accumulated interest costs of $9.5 million and $8.8 million as of December 31, 2023 and 2022, respectively. CYAPC maintains a trust to fund amounts due to the DOE for the disposal of pre-1983 spent nuclear fuel. For further information, see Note 5, "Marketable Securities," to the financial statements. Fees for disposal of nuclear fuel burned on or after April 7, 1983 were billed to member companies and paid to the DOE. Long-Term Debt Maturities: Long-term debt maturities on debt outstanding for the years 2024 through 2028 and thereafter are shown below. These amounts exclude PSNH rate reduction bonds, CYAPC pre-1983 spent nuclear fuel obligation, net unamortized premiums, discounts and debt issuance costs, and other fair value adjustments as of December 31, 2023: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2024 $ 1,950.0 $ 139.8 $ — $ — 2025 1,400.2 400.0 250.0 — 2026 1,390.2 — 300.0 — 2027 2,539.2 500.0 700.0 — 2028 1,978.5 — 150.0 — Thereafter 15,005.7 3,580.0 3,140.0 1,450.0 Total $ 24,263.8 $ 4,619.8 $ 4,540.0 $ 1,450.0

RATE REDUCTION BONDS AND VARIAB

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES	12 Months Ended
	Dec. 31, 2023
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: In May 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 in January 2018 to recover remaining costs resulting from the divestiture of PSNH’s generation assets. The proceeds were used by PSNH Funding to purchase PSNH’s stranded cost asset-recovery property, including its vested property right to bill, collect and adjust a non-bypassable stranded cost recovery charge from PSNH’s retail customers. The collections are used to pay principal, interest and other costs in connection with the RRBs. The RRBs are secured by the stranded cost asset-recovery property. Cash collections from the stranded cost recovery charges and funds on deposit in trust accounts are the sole source of funds to satisfy the debt obligation. PSNH is not the owner of the RRBs, and PSNH Funding’s assets and revenues are not available to pay PSNH’s creditors. The RRBs are non-recourse senior secured obligations of PSNH Funding and are not insured or guaranteed by PSNH or Eversource Energy. 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) As of December 31, PSNH Balance Sheets: 2023 2022 Restricted Cash - Current Portion (included in Current Assets) $ 30.0 $ 32.4 Restricted Cash - Long-Term Portion (included in Other Long-Term Assets) 3.2 3.2 Securitized Stranded Cost (included in Regulatory Assets) 392.5 435.7 Other Regulatory Liabilities (included in Regulatory Liabilities) 5.3 6.0 Accrued Interest (included in Other Current Liabilities) 6.3 6.9 Rate Reduction Bonds - Current Portion 43.2 43.2 Rate Reduction Bonds - Long-Term Portion 367.3 410.5 (Millions of Dollars) PSNH Income Statements: For the Years Ended December 31, 2023 2022 2021 Amortization of RRB Principal (included in Amortization of Regulatory (Liabilities)/Assets, Net) $ 43.2 $ 43.2 $ 43.2 Interest Expense on RRB Principal (included in Interest Expense) 15.7 17.0 18.4 Estimated principal payments on RRBs as of December 31, 2023, is summarized annually through 2028 and thereafter as follows: (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total PSNH $ 43.2 $ 43.2 $ 43.2 $ 43.2 $ 43.2 $ 194.5 $ 410.5 Variable Interest Entities - Other: The Company's variable interests outside of the consolidated group include contracts that are required by regulation and provide for regulatory recovery of contract costs and benefits through customer rates. Eversource, CL&P and NSTAR Electric hold variable interests in VIEs through agreements with certain entities that own single renewable energy or peaking generation power plants, with other independent power producers and with transmission businesses. Eversource, CL&P and NSTAR Electric do not control the activities that are economically significant to these VIEs or provide financial or other support to these VIEs. Therefore, Eversource, CL&P and NSTAR Electric do not consolidate these VIEs.

EMPLOYEE BENEFITS

EMPLOYEE BENEFITS	12 Months Ended
	Dec. 31, 2023
Postemployment Benefits [Abstract]
EMPLOYEE BENEFITS	EMPLOYEE BENEFITS A. Pension Benefits and Postretirement Benefits Other Than Pension Eversource provides defined benefit retirement plans (Pension Plans) that cover eligible employees and are subject to the provisions of ERISA, as amended by the Pension Protection Act of 2006. Eversource's policy is to annually fund the Pension Plans in an amount at least equal to an amount that will satisfy all federal funding requirements. 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 benefits provided under the PBOP Plans are not vested, and the Company has the right to modify any benefit provision subject to applicable laws at that time. Eversource annually funds postretirement costs through tax deductible contributions to external trusts. Funded Status: The Pension, SERP and PBOP Plans are accounted for under the multiple-employer approach, with each operating company's balance sheet reflecting its share of the funded status of the plans. Although Eversource maintains marketable securities in a benefit trust, the SERP Plans do not contain any assets. For further information, see Note 5, "Marketable Securities," to the financial statements. The following tables provide information on the plan benefit obligations, fair values of plan assets, and funded status: Pension and SERP As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Change in Benefit Obligation: Benefit Obligation as of Beginning of Year $ (5,220.1) $ (1,030.0) $ (1,110.4) $ (556.2) $ (6,729.7) $ (1,330.9) $ (1,448.4) $ (721.0) Service Cost (43.1) (12.3) (7.8) (4.3) (70.1) (18.7) (13.8) (6.9) Interest Cost (254.0) (50.5) (53.9) (27.3) (154.5) (31.3) (32.8) (16.9) Actuarial (Loss)/Gain (110.4) (19.7) (17.6) (11.6) 1,385.8 284.1 295.5 156.7 Benefits Paid - Pension 317.3 66.1 76.7 35.7 302.5 63.3 68.4 33.9 Benefits Paid - Lump Sum 28.9 — 5.3 1.0 33.0 — 14.8 1.0 Benefits Paid - SERP 43.0 0.3 0.2 0.4 12.9 0.3 0.2 0.4 Employee Transfers — (2.4) 0.5 — — 3.2 5.7 (3.4) Benefit Obligation as of End of Year $ (5,238.4) $ (1,048.5) $ (1,107.0) $ (562.3) $ (5,220.1) $ (1,030.0) $ (1,110.4) $ (556.2) Change in Pension Plan Assets: Fair Value of Pension Plan Assets as of $ 5,806.4 $ 1,172.0 $ 1,418.8 $ 618.0 $ 6,495.5 $ 1,323.8 $ 1,596.0 $ 694.6 Employer Contributions 5.0 — — — 80.0 — 15.0 — Actual Return on Pension Plan Assets 309.8 61.7 75.3 32.7 (433.6) (85.3) (103.3) (45.1) Benefits Paid - Pension (317.3) (66.1) (76.7) (35.7) (302.5) (63.3) (68.4) (33.9) Benefits Paid - Lump Sum (28.9) — (5.3) (1.0) (33.0) — (14.8) (1.0) Employee Transfers — 2.4 (0.5) — — (3.2) (5.7) 3.4 Fair Value of Pension Plan Assets as of End of Year $ 5,775.0 $ 1,170.0 $ 1,411.6 $ 614.0 $ 5,806.4 $ 1,172.0 $ 1,418.8 $ 618.0 Funded Status as of December 31st $ 536.6 $ 121.5 $ 304.6 $ 51.7 $ 586.3 $ 142.0 $ 308.4 $ 61.8 Actuarial (Loss)/Gain: For the year ended December 31, 2023, the actuarial loss was primarily attributable to a decrease in the discount rate, which resulted in an increase to Eversource's Pension and SERP Plans’ projected benefit obligation of $98.9 million. For the year ended December 31, 2022, the actuarial gain was primarily attributable to an increase in the discount rate, which resulted in a decrease to Eversource's Pension and SERP Plans’ projected benefit obligation of $1.48 billion. As of December 31, 2023 and 2022, the accumulated benefit obligation for the Pension and SERP Plans is as follows: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2023 $ 4,936.8 $ 977.8 $ 1,051.9 $ 522.1 2022 4,911.6 960.7 1,055.1 516.9 PBOP As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Change in Benefit Obligation: Benefit Obligation as of Beginning of Year $ (693.7) $ (127.9) $ (189.5) $ (74.6) $ (884.3) $ (165.5) $ (238.4) $ (92.3) Service Cost (7.6) (1.3) (1.2) (0.7) (11.6) (2.0) (2.0) (1.1) Interest Cost (33.8) (6.2) (9.2) (3.7) (20.2) (3.7) (5.3) (2.2) Actuarial Gain/(Loss) 5.0 4.4 (5.8) 0.8 173.6 33.0 39.4 15.2 Benefits Paid 52.7 10.0 16.7 6.1 52.1 10.4 16.6 6.0 Employee Transfers — — 0.5 (0.1) — (0.1) 0.2 (0.2) Plan Amendment 1.4 0.4 0.2 0.2 — — — — Impact of Acquisitions — — — — (3.3) — — — Benefit Obligation as of End of Year $ (676.0) $ (120.6) $ (188.3) $ (72.0) $ (693.7) $ (127.9) $ (189.5) $ (74.6) Change in Plan Assets: Fair Value of Plan Assets as of Beginning of Year $ 970.1 $ 120.6 $ 456.1 $ 72.3 $ 1,138.3 $ 145.7 $ 530.0 $ 88.0 Actual Return on Plan Assets 104.7 12.6 52.3 8.3 (119.6) (15.0) (57.0) (9.8) Employer Contributions 1.9 — — — 3.1 — — — Benefits Paid (52.3) (10.0) (16.7) (6.1) (51.7) (10.4) (16.6) (6.0) Employee Transfers — (0.2) (1.3) 0.2 — 0.3 (0.3) 0.1 Fair Value of Plan Assets as of End of Year $ 1,024.4 $ 123.0 $ 490.4 $ 74.7 $ 970.1 $ 120.6 $ 456.1 $ 72.3 Funded Status as of December 31st $ 348.4 $ 2.4 $ 302.1 $ 2.7 $ 276.4 $ (7.3) $ 266.6 $ (2.3) Actuarial Gain/(Loss): For the year ended December 31, 2023, the actuarial gain was primarily attributable to changes to termination, retirement, and dependency rates that were updated as a result of an experience study performed in 2023, updated census data, changes to plan provisions, and other assumption changes, which resulted in a decrease to the Eversource PBOP projected benefit obligation of $17 million. The actuarial gain was partially offset by a decrease in the discount rate, which resulted in an increase to the Eversource PBOP projected benefit obligation of $12 million. For the year ended December 31, 2022, the actuarial gain was primarily attributable to an increase in the discount rate, which resulted in a decrease to the Eversource PBOP projected benefit obligation of $180.1 million. A reconciliation of the prepaid assets and liabilities within the Eversource Pension, SERP and PBOP Plans’ funded status to the balance sheets is as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Prepaid Pension $ 672.2 $ 127.4 $ 306.5 $ 56.3 $ 756.7 $ 147.9 $ 310.2 $ 66.4 Prepaid PBOP 356.0 2.4 302.1 2.7 288.8 — 266.6 — Prepaid Pension and PBOP $ 1,028.2 $ 129.8 $ 608.6 $ 59.0 $ 1,045.5 $ 147.9 $ 576.8 $ 66.4 Accrued Pension $ — $ — $ — $ — $ 3.7 $ — $ — $ — Accrued SERP 135.6 5.9 1.9 4.6 166.7 5.9 1.8 4.6 Accrued PBOP 7.6 — — — 12.4 7.3 — 2.3 Less: Accrued SERP - current portion (19.4) (0.3) (0.2) (0.4) (47.3) (0.3) (0.2) (0.4) Accrued Pension, SERP and PBOP $ 123.8 $ 5.6 $ 1.7 $ 4.2 $ 135.5 $ 12.9 $ 1.6 $ 6.5 The following actuarial assumptions were used in calculating the Pension, SERP and PBOP Plans' year end funded status: Pension and SERP PBOP As of December 31, As of December 31, 2023 2022 2023 2022 Discount Rate 4.9% — 5.0% 5.1% — 5.2% 5.0% — 5.2% 5.2% Compensation/Progression Rate 3.5% — 4.0% 3.5% — 4.0% N/A For the Eversource Service PBOP Plan, the health care cost trend rate is not applicable. For the Aquarion PBOP Plan, the health care cost trend rate for pre-65 retirees is 6.75 percent, with an ultimate rate of 5 percent in 2031, and for post-65 retirees, the health care trend rate and ultimate rate is 3.5 percent. Expense: Eversource charges net periodic benefit plan expense/(income) for the Pension, SERP and PBOP Plans to its subsidiaries based on the actual participant demographic data for each subsidiary's participants. The actual investment return in the trust is allocated to each of the subsidiaries annually in proportion to the investment return expected to be earned during the year. The Company utilizes the spot rate methodology to estimate the discount rate for the service and interest cost components of benefit expense, which provides a relatively precise measurement by matching projected cash flows to the corresponding spot rates on the yield curve. The components of net periodic benefit plan expense/(income) for the Pension, SERP and PBOP Plans, prior to amounts capitalized as Property, Plant and Equipment or deferred as regulatory assets/(liabilities) for future recovery or refund, are shown below. The service cost component of net periodic benefit plan 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 plan 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 intercompany allocations of net periodic benefit plan expense/(income), as these amounts are cash settled on a short-term basis. Pension and SERP PBOP For the Year Ended December 31, 2023 For the Year Ended December 31, 2023 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 43.1 $ 12.3 $ 7.8 $ 4.3 $ 7.6 $ 1.3 $ 1.2 $ 0.7 Interest Cost 254.0 50.5 53.9 27.3 33.8 6.2 9.2 3.7 Expected Return on Plan Assets (465.0) (94.2) (113.8) (49.5) (77.1) (9.4) (36.9) (5.5) Actuarial Loss 45.8 2.5 17.1 1.5 — — — — Prior Service Cost/(Credit) 1.3 — 0.3 — (21.6) 1.1 (17.0) 0.4 Settlement Loss 12.4 — — — — — — — Total Net Periodic Benefit Plan Income $ (108.4) $ (28.9) $ (34.7) $ (16.4) $ (57.3) $ (0.8) $ (43.5) $ (0.7) Intercompany Income Allocations N/A $ (4.0) $ (3.0) $ (0.8) N/A $ (1.9) $ (2.1) $ (0.7) Pension and SERP PBOP For the Year Ended December 31, 2022 For the Year Ended December 31, 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 70.1 $ 18.7 $ 13.8 $ 6.9 $ 11.6 $ 2.0 $ 2.0 $ 1.1 Interest Cost 154.5 31.3 32.8 16.9 20.2 3.7 5.3 2.2 Expected Return on Plan Assets (523.6) (106.3) (128.4) (56.1) (89.9) (11.4) (42.4) (6.7) Actuarial Loss 116.0 16.2 32.8 7.9 — — — — Prior Service Cost/(Credit) 1.4 — 0.3 — (21.7) 1.1 (17.0) 0.4 Total Net Periodic Benefit Plan Income $ (181.6) $ (40.1) $ (48.7) $ (24.4) $ (79.8) $ (4.6) $ (52.1) $ (3.0) Intercompany Income Allocations N/A $ (16.0) $ (12.4) $ (3.6) N/A $ (3.7) $ (3.6) $ (1.2) Pension and SERP PBOP For the Year Ended December 31, 2021 For the Year Ended December 31, 2021 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 85.8 $ 23.0 $ 15.8 $ 8.9 $ 13.5 $ 2.3 $ 2.4 $ 1.2 Interest Cost 130.0 27.3 26.8 14.5 17.4 3.2 4.4 1.8 Expected Return on Plan Assets (437.5) (86.8) (108.1) (47.5) (79.1) (10.3) (36.9) (6.1) Actuarial Loss 243.9 45.5 61.6 20.7 8.9 1.8 2.4 0.7 Prior Service Cost/(Credit) 1.4 — 0.3 — (21.2) 1.1 (17.0) 0.4 Total Net Periodic Benefit Plan Expense/(Income) $ 23.6 $ 9.0 $ (3.6) $ (3.4) $ (60.5) $ (1.9) $ (44.7) $ (2.0) Intercompany Expense/(Income) Allocations N/A $ 8.0 $ 8.8 $ 2.7 N/A $ (1.6) $ (1.9) $ (0.6) The following actuarial assumptions were used to calculate Pension, SERP and PBOP expense amounts: Pension and SERP PBOP For the Years Ended December 31, For the Years Ended December 31, 2023 2022 2021 2023 2022 2021 Discount Rate 4.9% — 5.3% 2.2% — 3.2% 1.5% — 3.0% 5.1% — 5.4% 2.3% — 3.3% 1.8% — 3.1% Expected Long-Term Rate of Return 8.25% 8.25% 8.25% 8.25% 8.25% 8.25% Compensation/Progression Rate 3.5% — 4.0% 3.5% — 4.0% 3.5% — 4.0% N/A N/A N/A For the Aquarion Pension Plan, the expected long-term rate of return was 7.94 percent and 7 percent for the years ended December 31, 2023 and 2022, respectively. For the Aquarion PBOP Plan the expected long-term rate of return was 7 percent for the years ended December 31, 2023 and 2022 and the health care cost trend rate was a range of 3.5 percent to 7 percent for the year ended December 31, 2023 and 3.5 percent to 6.5 percent for the year ended December 31, 2022. Regulatory Assets and Accumulated Other Comprehensive Income/(Loss) Amounts: The Pension, SERP and PBOP Plans cover eligible employees, including, among others, employees of the regulated companies. The regulated companies record actuarial losses and gains and prior service costs and credits arising at the December 31st remeasurement date of the funded status of the benefit plans as a regulatory asset or regulatory liability in lieu of a charge to Accumulated Other Comprehensive Income/(Loss), reflecting ultimate recovery from customers through rates. Regulatory accounting is also applied to the portions of the Eversource Service retiree benefit costs that support the regulated companies, as these costs are also recovered from customers. Adjustments to the Pension, SERP and PBOP Plans' funded status for the unregulated companies are recorded on an after-tax basis to Accumulated Other Comprehensive Income/(Loss). For further information, see Note 2, "Regulatory Accounting," and Note 16, "Accumulated Other Comprehensive Income/(Loss)," to the financial statements. The following is a summary of the changes in plan assets and benefit obligations recognized in Regulatory Assets and Other Comprehensive Income (OCI) as well as amounts in Regulatory Assets and OCI that were reclassified as net periodic benefit expense during the years presented: Pension and SERP PBOP Regulatory Assets OCI Regulatory Assets OCI For the Years Ended December 31, For the Years Ended December 31, (Millions of Dollars) 2023 2022 2023 2022 2023 2022 2023 2022 Actuarial (Gain)/Loss Arising During the Year $ 251.1 $ (431.6) $ 14.0 $ 4.6 $ (32.0) $ 36.8 $ (0.3) $ (0.8) Actuarial Loss Reclassified as Net Periodic Benefit Expense (38.8) (107.0) (7.0) (9.0) — — — — Settlement Loss — — (12.4) — — — — — Prior Service Credit Arising During the Year — — — — (0.9) — — — Prior Service (Cost)/Credit Reclassified as Net Periodic (1.2) (1.2) (0.1) (0.2) 21.8 21.8 (0.2) (0.1) The following is a summary of the remaining Regulatory Assets and Accumulated Other Comprehensive Income amounts that have not been recognized as components of net periodic benefit expense as of December 31, 2023 and 2022: Regulatory Assets as of December 31, AOCI as of December 31, (Millions of Dollars) 2023 2022 2023 2022 Pension and SERP Actuarial Loss $ 1,101.0 $ 888.7 $ 56.5 $ 61.9 Prior Service Cost 2.9 4.1 0.3 0.4 PBOP Actuarial Loss $ 49.8 $ 81.8 $ 2.4 $ 2.7 Prior Service (Credit)/Cost (87.4) (108.3) 0.7 0.9 The difference between the actual return and calculated expected return on plan assets for the Pension and PBOP Plans, as well as changes in actuarial assumptions impacting the projected benefit obligation, are recorded as unamortized actuarial gains or losses arising during the year in Regulatory Assets or Accumulated Other Comprehensive Income/(Loss). Unamortized actuarial gains or losses are amortized as a component of pension and PBOP expense over the estimated average future employee service period using the corridor approach. Estimated Future Benefit Payments: The following benefit payments, which reflect expected future service, are expected to be paid by the Pension, SERP and PBOP Plans: (Millions of Dollars) 2024 2025 2026 2027 2028 2029 - 2033 Pension and SERP $ 370.2 $ 367.1 $ 370.8 $ 373.8 $ 375.0 $ 1,864.3 PBOP 55.2 54.7 53.8 52.8 51.8 241.1 Eversource Contributions: Based on the current status of the Pension Plans and federal pension funding requirements, there is no minimum funding requirement for our Eversource Service Pension Plan in 2024 and we do not expect to make pension contributions in 2024. We do not expect to make any contributions to the Eversource Service PBOP Plan in 2024. Eversource contributed $5.0 million and $1.9 million to the Aquarion Pension and PBOP Plans, respectively, in 2023. Eversource currently estimates contributing $5.0 million and $2.4 million to the Aquarion Pension and PBOP Plans, respectively, in 2024. Fair Value of Pension and PBOP Plan Assets: Pension and PBOP funds are held in external trusts. Trust assets, including accumulated earnings, must be used exclusively for Pension and PBOP payments. Eversource's investment strategy for its Pension and PBOP Plans is to maximize the long-term rates of return on these plans' assets within an acceptable level of risk. The investment guidelines for each asset category includes a diversification of asset types, fund strategies and fund managers and it establishes target asset allocations that are routinely reviewed and periodically rebalanced. PBOP assets are comprised of assets held in the PBOP Plan trust, as well as specific assets within the Pension Plan trust (401(h) assets). The investment policy and strategy of the 401(h) assets is consistent with that of the defined benefit pension plan. Eversource's expected long-term rates of return on Pension and PBOP Plan assets are based on target asset allocation assumptions and related expected long-term rates of return. In developing its expected long-term rate of return assumptions for the Pension and PBOP Plans, Eversource evaluated input from consultants, as well as long-term inflation assumptions and historical returns. Management has assumed long-term rates of return of 8.25 percent for the Eversource Service Pension Plan assets, the Eversource Service PBOP Plan assets and the Aquarion Pension Plan assets, and a 7 percent long-term rate of return for the Aquarion PBOP Plan, to estimate its 2024 Pension and PBOP costs. These long-term rates of return are based on the assumed rates of return for the target asset allocations as follows: As of December 31, 2023 2022 Target Asset Allocation Assumed Rate of Return Target Asset Allocation Assumed Rate of Return Eversource Pension Plan Eversource PBOP Plan Eversource Pension Plan and PBOP Plan Eversource Pension Plan and PBOP Plan Equity Securities: United States — % 20.0 % 8.5 % 15.0 % 8.5 % Global 20.0 % — % 8.75 % 10.0 % 8.75 % Non-United States — % 11.0 % 8.5 % 8.0 % 8.5 % Emerging Markets — % 6.0 % 10.0 % 4.0 % 10.0 % Debt Securities: Fixed Income 16.0 % 17.0 % 5.5 % 13.0 % 4.0 % Public High Yield Fixed Income 5.0 % — % 7.5 % 4.0 % 6.5 % United States Treasuries 11.0 % — % 4.5 % — % — % Private Debt 10.0 % 13.0 % 10.0 % 13.0 % 9.0 % Private Equity 23.0 % 18.0 % 12.0 % 18.0 % 12.0 % Real Assets 15.0 % 15.0 % 7.5 % 15.0 % 7.5 % The following tables present, by asset category, the Pension and PBOP Plan assets recorded at fair value on a recurring basis by the level in which they are classified within the fair value hierarchy: Pension Plan Fair Value Measurements as of December 31, (Millions of Dollars) 2023 2022 Asset Category: Level 1 Level 2 Uncategorized Total Level 1 Level 2 Uncategorized Total Equity Securities $ 374.0 $ — $ 853.0 $ 1,227.0 $ 407.7 $ — $ 1,102.2 $ 1,509.9 Fixed Income (1) 354.6 340.9 1,516.4 2,211.9 277.1 78.5 1,598.8 1,954.4 Private Equity — — 1,685.3 1,685.3 — — 1,684.9 1,684.9 Real Assets 173.6 — 722.1 895.7 181.8 — 731.0 912.8 Total $ 902.2 $ 340.9 $ 4,776.8 $ 6,019.9 $ 866.6 $ 78.5 $ 5,116.9 $ 6,062.0 Less: 401(h) PBOP Assets (2) (244.9) (255.6) Total Pension Assets $ 5,775.0 $ 5,806.4 PBOP Plan Fair Value Measurements as of December 31, (Millions of Dollars) 2023 2022 Asset Category: Level 1 Level 2 Uncategorized Total Level 1 Level 2 Uncategorized Total Equity Securities $ 139.1 $ — $ 212.1 $ 351.2 $ 153.2 $ — $ 183.5 $ 336.7 Fixed Income 33.4 43.0 159.8 236.2 18.2 40.2 141.1 199.5 Private Equity — — 87.7 87.7 — — 70.9 70.9 Real Assets 70.5 — 33.9 104.4 71.2 — 36.2 107.4 Total $ 243.0 $ 43.0 $ 493.5 $ 779.5 $ 242.6 $ 40.2 $ 431.7 $ 714.5 Add: 401(h) PBOP Assets (2) 244.9 255.6 Total PBOP Assets $ 1,024.4 $ 970.1 (1) Fixed Income investments classified as Level 1 as of December 31, 2023 and 2022 include pending purchases and pending redemption settlements of $31 million and $138 million, respectively. (2) The assets of the Pension Plan include a 401(h) account that has been allocated to provide health and welfare postretirement benefits under the PBOP Plan. The Company values assets based on observable inputs when available. Equity securities, exchange traded funds and futures contracts classified as Level 1 in the fair value hierarchy are priced based on the closing price on the primary exchange as of the balance sheet date. Fixed income securities, such as government issued securities and corporate bonds, are included in Level 2 and are valued using pricing models, quoted prices of securities with similar characteristics or discounted cash flows. The pricing models utilize observable inputs such as recent trades for the same or similar instruments, yield curves, discount margins and bond structures. Swaps are valued using pricing models that incorporate interest rates and equity and fixed income index closing prices to determine a net present value of the cash flows. Certain investments, such as commingled funds, private equity investments, fixed income funds, real asset funds and hedge funds are valued using the net asset value (NAV) as a practical expedient. Assets valued at NAV are uncategorized in the fair value hierarchy. These investments are structured as investment companies offering shares or units to multiple investors for the purpose of providing a return. Commingled funds are recorded at NAV provided by the asset manager, which is based on the market prices of the underlying equity securities. Private Equity investments, Fixed Income partnership funds and Real Assets are valued using the NAV provided by the partnerships, which are based on discounted cash flows of the underlying investments, real estate appraisals or public market comparables of the underlying investments, or the NAV of underlying assets held in hedge funds. Equity Securities investments in United States, Global, Non-United States and Emerging Markets that are uncategorized include investments in commingled funds and hedge funds that are overlaid with equity index swaps and futures contracts. Fixed Income investments that are uncategorized include investments in commingled funds, fixed income funds that invest in a variety of opportunistic credit and private debt strategies, and hedge funds that are overlaid with fixed income futures. Eversource maintains defined contribution plans on behalf of eligible participants. The Eversource 401k Plan provides for employee and employer contributions up to statutory limits. For eligible employees, the Eversource 401k Plan provides employer matching contributions of either 100 percent up to a maximum of three percent of eligible compensation or 50 percent up to a maximum of eight percent of eligible compensation. The Eversource 401k Plan also contains a K-Vantage feature for the benefit of eligible participants, which provides an additional annual employer contribution based on age and years of service. K-Vantage participants are not eligible to actively participate in the Eversource Pension Plan. The total Eversource 401k Plan employer matching contributions, including the K-Vantage contributions, were as follows: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2023 $ 67.3 $ 9.0 $ 13.7 $ 5.4 2022 59.9 7.7 12.8 4.8 2021 55.5 7.0 12.2 4.3 Share-based compensation awards are recorded using a fair-value based method at the date of grant. Eversource, CL&P, NSTAR Electric and PSNH record compensation expense related to these awards, as applicable, for shares issued to their respective employees and officers, as well as for the allocation of costs associated with shares issued to Eversource's service company employees and officers that support CL&P, NSTAR Electric and PSNH. Eversource Incentive Plans: Eversource maintains long-term equity-based incentive plans in which Eversource, CL&P, NSTAR Electric and PSNH employees, officers and board members are eligible to participate. The incentive plans authorize Eversource to grant up to 7,400,000 new shares for various types of awards, including RSUs and performance shares, to eligible employees, officers, and board members. As of December 31, 2023 and 2022, Eversource had 4,587,376 and 903,183 common shares, respectively, available for issuance under these plans. Eversource accounts for its various share-based plans as follows: • RSUs - Eversource records compensation expense, net of estimated forfeitures, on a straight-line basis over the requisite service period based upon the fair value of Eversource's common shares at the date of grant. The par value of RSUs is reclassified to Common Stock from Capital Surplus, Paid In as RSUs become issued as common shares. • Performance Shares - Eversource records compensation expense, net of estimated forfeitures, over the requisite service period. Performance shares vest based upon the extent to which Company goals are achieved. Vesting of outstanding performance shares is based upon the Company's EPS growth over the requisite service period and level of payout is determined based on the total shareholder return as compared to the Edison Electric Institute (EEI) Index during the requisite service period. The fair value of performance shares is determined at the date of grant using a lattice model. Compensation expense is subject to volatility until payout is established. RSUs: Eversource granted RSUs under the annual long-term incentive programs that are subject to three-year graded vesting schedules for employees, and one-year graded vesting schedules, or immediate vesting, for board members. RSUs are paid in shares, reduced by amounts sufficient to satisfy withholdings for income taxes, subsequent to vesting. A summary of RSU transactions is as follows: RSUs Weighted Average Outstanding as of December 31, 2022 629,734 $ 68.52 Granted 248,124 $ 76.42 Shares Issued (181,409) $ 87.09 Forfeited (24,207) $ 83.43 Outstanding as of December 31, 2023 672,242 $ 65.89 The weighted average grant-date fair value of RSUs granted for the years ended December 31, 2023, 2022 and 2021 was $76.42, $85.96 and $81.89, respectively. As of December 31, 2023 and 2022, the number and weighted average grant-date fair value of unvested RSUs was 326,581 and $80.76 per share, and 300,592 and $87.21 per share, respectively. During 2023, there were 199,145 RSUs at a weighted average grant-date fair value of $86.92 per share that vested during the year and were either paid or deferred. As of December 31, 2023, 345,661 RSUs were fully vested and deferred and an additional 310,252 are expected to vest. Performance Shares: Eversource granted performance shares under the annual long-term incentive programs that vest based upon the extent to which Company goals are achieved at the end of three-year performance measurement periods. Performance shares are paid in shares, after the performance measurement period. A summary of performance share transactions is as follows: Performance Shares Weighted Average Outstanding as of December 31, 2022 547,290 $ 87.49 Granted 278,983 $ 83.39 Shares Issued (125,677) $ 90.49 Forfeited (36,172) $ 85.13 Outstanding as of December 31, 2023 664,424 $ 85.33 The weighted average grant-date fair value of performance shares granted for the years ended December 31, 2023, 2022 and 2021 was $83.39, $83.34 and $76.08, respectively. As of December 31, 2023 and 2022, the number and weighted average grant-date fair value of unvested performance shares was 485,480 and $85.20 per share, and 457,069 and $88.43 per share, respectively. During 2023, there were 214,742 performance shares at a weighted average grant-date fair value of $89.70 per share that vested during the year and were either paid or deferred. As of December 31, 2023, 178,944 performance shares were fully vested and deferred. Compensation Expense: The total compensation expense and associated future income tax benefits recognized by Eversource, CL&P, NSTAR Electric and PSNH for share-based compensation awards were as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Compensation Expense $ 27.8 $ 33.4 $ 28.2 Future Income Tax Benefit 7.3 8.7 7.3 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Compensation Expense $ 8.7 $ 8.7 $ 3.0 $ 10.0 $ 10.7 $ 3.6 $ 8.8 $ 9.0 $ 3.0 Future Income Tax Benefit 2.3 2.3 0.8 2.6 2.8 0.9 2.3 2.3 0.8 As of December 31, 2023, there was $31.3 million of total unrecognized compensation expense related to nonvested share-based awards for Eversource, including $5.8 million for CL&P, $8.6 million for NSTAR Electric, and $1.9 million for PSNH. This cost is expected to be recognized ratably over a weighted-average period of 1.81 years for Eversource, CL&P, NSTAR Electric and PSNH. An income tax rate of 26 percent was used to estimate the tax effect on total share-based payments determined under the fair-value based method for all awards. The Company issues treasury shares to settle fully vested RSUs and performance shares under the Company's incentive plans. For the year ended December 31, 2023, a tax deficiency associated with the distribution of stock compensation awards increased income tax expense by $0.5 million, which decreased cash flows from operating activities on the statements of cash flows. For the years ended December 31, 2022 and 2021, excess tax benefits associated with the distribution of stock compensation awards reduced income tax expense by $2.1 million and $4.0 million, respectively, which increased cash flows from operating activities on the statements of cash flows. Eversource provides retirement and other benefits for certain current and past company officers. These benefits are accounted for on an accrual basis and expensed over a period equal to the service lives of the employees. The actuarially-determined liability for these benefits is included in Other Current and Long-Term Liabilities on the balance sheets. The related expense, which includes the allocation of expense associated with Eversource's service company officers that support CL&P, NSTAR Electric and PSNH, is included in Operations and Maintenance Expense on the income statements. The liability and expense amounts are as follows: Eversource (Millions of Dollars) As of and For the Years Ended December 31, 2023 2022 2021 Actuarially-Determined Liability $ 32.6 $ 43.4 $ 42.8 Other Retirement Benefits Expense (1) 2.6 10.9 2.2 As of and For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Actuarially-Determined Liability $ 0.2 $ — $ 1.1 $ 0.2 $ 0.1 $ 1.3 $ 0.2 $ 0.1 $ 1.5 Other Retirement Benefits Expense (1) 0.8 0.8 0.4 4.0 3.7 1.3 0.7 0.7 0.3 (1) Other Retirement Benefits Expense in 2022 includes a one-time special retirement benefit payable of $9.2 million, which was paid in 2023.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The components of income tax expense are as follows: Eversource (Millions of Dollars) For the Years Ended December 31, 2023 2022 2021 Current Income Taxes: Federal $ 75.8 $ 95.8 $ 21.5 State 0.6 13.6 (21.6) Total Current 76.4 109.4 (0.1) Deferred Income Taxes, Net: Federal (0.9) 198.8 199.7 State 86.3 148.0 147.4 Total Deferred 85.4 346.8 347.1 Investment Tax Credits, Net (2.1) (2.6) (2.8) Income Tax Expense $ 159.7 $ 453.6 $ 344.2 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Current Income Taxes: Federal $ (10.8) $ 50.7 $ (40.0) $ 106.2 $ 55.0 $ 29.6 $ 15.0 $ 52.3 $ 43.1 State (2.3) 7.8 (20.0) 20.1 8.7 5.9 (7.0) 6.2 10.8 Total Current (13.1) 58.5 (60.0) 126.3 63.7 35.5 8.0 58.5 53.9 Deferred Income Taxes, Net: Federal 130.3 50.1 81.2 17.2 35.6 5.9 76.3 16.3 (14.9) State 53.7 46.1 37.8 28.2 42.4 9.9 47.6 41.2 0.4 Total Deferred 184.0 96.2 119.0 45.4 78.0 15.8 123.9 57.5 (14.5) Investment Tax Credits, Net — (1.7) — (0.5) (1.7) — (0.6) (1.7) — Income Tax Expense $ 170.9 $ 153.0 $ 59.0 $ 171.2 $ 140.0 $ 51.3 $ 131.3 $ 114.3 $ 39.4 A reconciliation between income tax expense and the expected tax expense at the statutory rate is as follows: Eversource (Millions of Dollars, except percentages) For the Years Ended December 31, 2023 2022 2021 (Loss)/Income Before Income Tax Expense $ (275.0) $ 1,866.0 $ 1,572.3 Statutory Federal Income Tax Expense at 21% (57.7) 391.9 330.2 Tax Effect of Differences: Depreciation (25.8) (17.1) (18.1) Investment Tax Credit Amortization (2.1) (2.6) (2.8) State Income Taxes, Net of Federal Impact (11.4) 75.9 54.4 Dividends on ESOP (5.3) (5.1) (5.1) Tax Asset Valuation Allowance/Reserve Adjustments 295.8 51.6 44.6 Tax Deficiency/(Excess Stock Benefit) 0.5 (2.1) (4.0) EDIT Amortization (51.5) (49.1) (69.1) Other, Net 17.2 10.2 14.1 Income Tax Expense $ 159.7 $ 453.6 $ 344.2 Effective Tax Rate (58.1) % 24.3 % 21.9 % . For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars, except percentages) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Income Before Income Tax Expense $ 689.6 $ 697.5 $ 254.7 $ 704.1 $ 632.4 $ 222.9 $ 533.0 $ 590.9 $ 189.8 Statutory Federal Income Tax Expense at 21% 144.9 146.5 53.5 147.9 132.8 46.8 111.9 124.1 39.9 Tax Effect of Differences: Depreciation (5.6) (8.8) (1.0) (3.7) (4.2) 0.9 (6.4) (3.4) (0.2) Investment Tax Credit Amortization — (1.7) — (0.5) (1.7) — (0.6) (1.7) — State Income Taxes, Net of Federal Impact (10.7) 42.5 14.1 (6.6) 40.3 12.5 (4.6) 37.5 8.9 Tax Asset Valuation 51.3 — — 44.7 — — 36.7 — — Tax Deficiency/(Excess Stock Benefit) 0.2 0.2 0.1 (0.7) (0.8) (0.3) (1.5) (1.4) (0.5) EDIT Amortization (10.5) (28.4) (6.8) (9.2) (29.2) (7.7) (9.8) (43.2) (10.5) Other, Net 1.3 2.7 (0.9) (0.7) 2.8 (0.9) 5.6 2.4 1.8 Income Tax Expense $ 170.9 $ 153.0 $ 59.0 $ 171.2 $ 140.0 $ 51.3 $ 131.3 $ 114.3 $ 39.4 Effective Tax Rate 24.8 % 21.9 % 23.2 % 24.3 % 22.1 % 23.0 % 24.6 % 19.3 % 20.8 % Eversource, CL&P, NSTAR Electric and PSNH file a consolidated federal income tax return and unitary, combined and separate state income tax returns. These entities are also parties to a tax allocation agreement under which taxable subsidiaries do not pay any more taxes than they would have otherwise paid had they filed a separate company tax return, and subsidiaries generating tax losses, if any, are paid for their losses when utilized. Deferred tax assets and liabilities are recognized for the future tax effects of temporary differences between the carrying amounts and the tax basis of assets and liabilities. The tax effect of temporary differences is accounted for in accordance with the rate-making treatment of the applicable regulatory commissions and relevant accounting authoritative literature. The tax effects of temporary differences that give rise to the net accumulated deferred income tax obligations are as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Deferred Tax Assets: Employee Benefits $ 244.5 $ 29.9 $ 66.8 $ 13.0 $ 228.9 $ 25.3 $ 57.4 $ 11.6 Derivative Liabilities 33.0 33.0 — — 53.8 53.8 — — Regulatory Deferrals - Liabilities 452.0 94.4 291.5 23.8 529.5 146.6 285.7 42.1 Allowance for Uncollectible Accounts 143.8 79.6 21.5 3.9 125.5 60.5 20.7 7.9 Tax Effect - Tax Regulatory Liabilities 739.0 320.7 227.1 95.5 762.9 324.6 241.8 97.8 Net Operating Loss Carryforwards 13.8 — — — 16.7 — — — Purchase Accounting Adjustment 56.7 — — — 62.0 — — — Equity Method Wind Investments 584.9 — — — — — — — Other 200.1 125.3 25.0 23.4 176.6 109.5 20.5 21.3 Total Deferred Tax Assets 2,467.8 682.9 631.9 159.6 1,955.9 720.3 626.1 180.7 Less: Valuation Allowance (1) 328.1 80.6 — — 82.8 63.3 — — Net Deferred Tax Assets $ 2,139.7 $ 602.3 $ 631.9 $ 159.6 $ 1,873.1 $ 657.0 $ 626.1 $ 180.7 Deferred Tax Liabilities: Accelerated Depreciation and Other $ 5,103.3 $ 1,703.4 $ 1,728.6 $ 566.5 $ 4,793.7 $ 1,602.0 $ 1,643.7 $ 523.8 Property Tax Accruals 95.0 42.0 39.8 6.3 95.3 40.7 41.3 6.7 Regulatory Amounts: Regulatory Deferrals - Assets 1,512.3 470.0 474.5 250.3 1,251.9 406.4 407.9 165.2 Tax Effect - Tax Regulatory Assets 284.0 191.9 10.5 8.3 271.7 185.6 10.7 7.9 Goodwill-related Regulatory Asset - 1999 Merger 72.2 — 61.9 — 76.8 — 65.9 — Employee Benefits 282.0 38.8 146.7 16.8 305.5 45.0 140.8 18.7 Derivative Assets 6.4 6.4 — — 10.5 10.5 — — Other 88.2 9.9 19.5 2.9 135.6 6.8 16.7 21.2 Total Deferred Tax Liabilities $ 7,443.4 $ 2,462.4 $ 2,481.5 $ 851.1 $ 6,941.0 $ 2,297.0 $ 2,327.0 $ 743.5 (1) As of December 31, 2023, the Eversource Valuation Allowance of $328.1 million includes $224.0 million related to the impairment of Eversource’s offshore wind investments. 2022 Federal Legislation: On August 16, 2022, the Inflation Reduction Act of 2022 (IRA) was signed into law. This is a broad package of legislation that includes incentives and support for clean energy resource development. Most notable for Eversource, the investment tax credit (ITC) on offshore wind projects increases from 30 percent to 40 percent if certain requirements for labor and domestic content are met. The act also re-establishes the production tax credit for solar and wind energy projects, gives increased credit for projects in certain communities, and sets credits for qualifying clean energy generation and energy storage projects. The tax provisions of the IRA provide additional incentives for offshore wind projects and could reduce retail electricity costs for our customers related to those clean energy investments. The IRA includes other tax provisions focused on implementing a 15 percent minimum tax on adjusted financial statement income and a one percent excise tax on corporate share repurchases. The Department of Treasury and the Internal Revenue Service issued some guidance during 2023; however, they are expected to issue additional needed guidance with respect to the application of the newly enacted IRA provisions in the future. We will continue to monitor and evaluate impacts on our consolidated financial statements. We currently do not expect the alternative minimum tax change to have a material impact on our earnings, financial condition or cash flows. Carryforwards: The following table provides the amounts and expiration dates of state tax credit and loss carryforwards and federal tax credit and net operating loss carryforwards: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Expiration Range Eversource CL&P NSTAR PSNH Expiration Range State Net Operating Loss $ 243.4 $ — $ — $ — 2023 - 2041 $ 288.1 $ — $ — $ — 2022 - 2041 State Tax Credit 228.5 157.5 — — 2023 - 2028 204.5 137.7 — — 2022 - 2027 State Charitable Contribution 7.9 — — — 2023 - 2027 20.1 — — — 2022 - 2026 In 2023, the Company increased its valuation allowance reserve for state credits by $21.3 million ($17.3 million for CL&P), net of tax, to reflect an update for expiring tax credits. In 2022 , the Company increased its valuation allowance reserve for state credits by $21.3 million ($18.8 million for CL&P), net of tax, to reflect an update for expiring tax credits. For 2023, state credit and state loss carryforwards have been partially reserved by a valuation allowance of $104.1 million (net of tax) and for 2022, state credit and state loss carryforwards were partially reserved by a valuation allowance of $82.8 million (net of tax). Unrecognized Tax Benefits: A reconciliation of the activity in unrecognized tax benefits, all of which would impact the effective tax rate if recognized, is as follows: (Millions of Dollars) Eversource CL&P Balance as of January 1, 2021 $ 61.8 $ 25.8 Gross Increases - Current Year 11.3 3.8 Gross Decreases - Prior Year (0.3) (0.6) Lapse of Statute of Limitations (7.0) (2.8) Balance as of December 31, 2021 65.8 26.2 Gross Increases - Current Year 11.5 3.5 Gross Decreases - Prior Year (2.4) (0.9) Lapse of Statute of Limitations (7.8) (3.3) Balance as of December 31, 2022 67.1 25.5 Gross Increases - Current Year 23.4 4.0 Gross Increases - Prior Year 0.1 0.1 Gross Decreases - Prior Year (0.1) — Lapse of Statute of Limitations (9.2) (3.8) Balance as of December 31, 2023 $ 81.3 $ 25.8 Interest and Penalties: Interest on uncertain tax positions is recorded and generally classified as a component of Other Interest Expense on the statements of income. However, when resolution of uncertainties results in the Company receiving interest income, any related interest benefit is recorded in Other Income, Net on the statements of income. No penalties have been recorded. The amount of interest expense recognized on uncertain tax positions was $0.3 million for the year ended December 31, 2023. There was no interest expense/(income) recognized on uncertain tax positions for the years ended December 31, 2022 or 2021. Accrued interest payable was $0.4 million and $0.1 million as of December 31, 2023 and 2022, respectively. Tax Positions: During 2023 and 2022, Eversource did not resolve any of its uncertain tax positions. Open Tax Years: The following table summarizes Eversource, CL&P, NSTAR Electric, and PSNH's tax years that remain subject to examination by major tax jurisdictions as of December 31, 2023: Description Tax Years Federal 2023 Connecticut 2020 - 2023 Massachusetts 2020 - 2023 New Hampshire 2020 - 2023 Eversource does not estimate to have an earnings impact related to unrecognized tax benefits during the next twelve months.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2023
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. Environmental reserves are accrued when assessments indicate it is probable that a liability has been incurred and an amount can be reasonably estimated. The approach used estimates the liability based on the most likely action plan from a variety of available remediation options, including no action required or several different remedies ranging from establishing institutional controls to full site remediation and monitoring. These liabilities are estimated on an undiscounted basis and do not assume that the amounts are recoverable from insurance companies or other third parties. The environmental reserves include sites at different stages of discovery and remediation and do not include any unasserted claims. 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. The amounts recorded as environmental reserves are included in Other Current Liabilities and Other Long-Term Liabilities on the balance sheets and represent management's best estimate of the liability for environmental costs, and take into consideration site assessment, remediation and long-term monitoring costs. The environmental reserves also take into account recurring costs of managing hazardous substances and pollutants, mandated expenditures to remediate contaminated sites and any other infrequent and non-recurring clean-up costs. A reconciliation of the activity in the environmental reserves is as follows: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Balance as of January 1, 2022 $ 115.4 $ 13.9 $ 3.3 $ 6.3 Additions 12.6 0.9 0.4 0.5 Payments/Reductions (5.4) (0.9) (0.3) (0.7) Balance as of December 31, 2022 122.6 13.9 3.4 6.1 Additions 16.8 2.6 2.5 1.7 Payments/Reductions (11.2) (2.7) (0.5) (0.2) Balance as of December 31, 2023 $ 128.2 $ 13.8 $ 5.4 $ 7.6 The number of environmental sites for which remediation or long-term monitoring, preliminary site work or site assessment is being performed are as follows: Eversource CL&P NSTAR Electric PSNH 2023 65 16 12 8 2022 59 13 10 8 The increase in the reserve balance was due primarily to the addition of one environmental site at NSTAR Gas, two additional sites at NSTAR Electric, three additional sites at CL&P, and changes in cost estimates at certain MGP sites at our natural gas companies and PSNH for which additional remediation will be required. Included in the number of sites and reserve amounts above are former MGP sites that were operated several decades ago and manufactured natural 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 $117.1 million and $112.6 million as of December 31, 2023 and 2022, respectively, and related primarily to the natural gas business segment. As of December 31, 2023, for 19 environmental sites (11 for CL&P and 1 for NSTAR Electric) that are included in the Company's reserve for environmental costs, management cannot reasonably estimate the exposure to loss in excess of the reserve, or range of loss, as these sites are under investigation and/or there is significant uncertainty as to what remedial actions, if any, the Company may be required to undertake. As of December 31, 2023, $39.9 million (including $12.6 million for CL&P and $0.3 million for NSTAR Electric) had been accrued as a liability for these sites. As of December 31, 2023, for 7 environmental sites (1 for CL&P) that are included in the Company's reserve for environmental costs, the information known and the nature of the remediation options allow for the Company to estimate the range of losses for environmental costs. As of December 31, 2023, $29.4 million (including $0.4 million for CL&P) has been accrued as a liability for these sites, which represents the low end of the range of the liabilities for environmental costs. Management believes that additional losses of up to approximately $17.7 million ($0.5 million at CL&P) may be incurred in executing current remediation plans for these sites. As of December 31, 2023, for the remaining 39 environmental sites (including 4 for CL&P, 11 for NSTAR Electric and 8 for PSNH) that are included in the Company's reserve for environmental costs, the $58.9 million accrual (including $0.8 million for CL&P, $5.1 million for NSTAR Electric and $7.6 million for PSNH) represents management's best estimate of the probable liability and no additional loss is estimable at this time. Estimated Future Annual Costs: The estimated future annual costs of significant executed, non-cancelable, long-term contractual arrangements in effect as of December 31, 2023 are as follows: Eversource (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 769.4 $ 863.0 $ 867.9 $ 897.6 $ 893.1 $ 5,368.8 $ 9,659.8 Natural Gas Procurement 423.2 402.3 317.8 264.8 236.0 1,211.8 2,855.9 Purchased Power and Capacity 86.7 75.2 2.9 2.7 2.7 4.5 174.7 Peaker CfDs 17.2 14.1 12.8 9.1 6.8 43.7 103.7 Transmission Support Commitments 19.3 22.2 27.4 31.1 31.1 31.1 162.2 Total $ 1,315.8 $ 1,376.8 $ 1,228.8 $ 1,205.3 $ 1,169.7 $ 6,659.9 $ 12,956.3 CL&P (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 618.8 $ 628.3 $ 628.0 $ 631.2 $ 632.2 $ 2,087.8 $ 5,226.3 Purchased Power and Capacity 83.8 72.4 0.1 — — — 156.3 Peaker CfDs 17.2 14.1 12.8 9.1 6.8 43.7 103.7 Transmission Support Commitments 7.6 8.8 10.8 12.3 12.3 12.3 64.1 Total $ 727.4 $ 723.6 $ 651.7 $ 652.6 $ 651.3 $ 2,143.8 $ 5,550.4 NSTAR Electric (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 123.0 $ 202.9 $ 206.5 $ 209.3 $ 205.1 $ 2,983.5 $ 3,930.3 Purchased Power and Capacity 2.9 2.8 2.8 2.7 2.7 4.5 18.4 Transmission Support Commitments 7.6 8.7 10.8 12.3 12.3 12.3 64.0 Total $ 133.5 $ 214.4 $ 220.1 $ 224.3 $ 220.1 $ 3,000.3 $ 4,012.7 PSNH (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 27.6 $ 31.8 $ 33.4 $ 57.1 $ 55.8 $ 297.5 $ 503.2 Transmission Support Commitments 4.1 4.7 5.8 6.5 6.5 6.5 34.1 Total $ 31.7 $ 36.5 $ 39.2 $ 63.6 $ 62.3 $ 304.0 $ 537.3 The contractual obligations table above does not include CL&P's, NSTAR Electric's or PSNH's standard/basic service contracts for the purchase of energy supply, the amounts of which vary with customers' energy needs. Renewable Energy Purchase Contracts: Renewable energy purchase contracts include non-cancellable commitments under contracts of CL&P, NSTAR Electric and PSNH for the purchase of energy and capacity from renewable energy facilities. Such contracts extend through 2044 for CL&P and NSTAR Electric and 2033 for PSNH. Renewable Energy and Purchase Contracts includes long-term commitments of NSTAR Electric pertaining to the Vineyard Wind LLC contract awarded under the Massachusetts Clean Energy 83C procurement solicitation. NSTAR Electric, along with other Massachusetts distribution companies, entered into 20-year contracts to purchase electricity generated by this 800 megawatt offshore wind project. Construction on the Vineyard Wind project commenced in 2022. Estimated energy costs under this contract are expected to begin when the facilities are in service in 2024 and range between $100 million and $200 million per year und er NSTAR Electric’s 20-year contract, totaling approximately $2.6 billion. As required by 2018 regulation, CL&P and UI each entered into PURA-approved ten-year contracts in 2019 to purchase a combined total of approximately 9 million MWh annually from the Millstone Nuclear Power Station generation facility, which represents a combined amount of approximately 50 percent of the facility's output (approximately 40 percent by CL&P). Also as required by 2018 regulation, CL&P and UI each entered into PURA-approved eight-year contracts in 2019 to purchase a combined amount of approximately 18 percent of the Seabrook Nuclear Power Plant’s output (approximately 15 percent by CL&P) beginning January 1, 2022. The total estimated remaining future cost of the Millstone Nuclear Power Station and Seabrook Nuclear Power Plant energy purchase contracts are $2.4 billion and are reflected in the table above. CL&P sells the energy purchased under these contracts into the market and uses the proceeds from these energy sales to offset the contract costs. As the net costs under these contracts are recovered from customers in future rates, the contracts do not have an impact on the net income of CL&P. These contracts do not meet the definition of a derivative, and accordingly, the costs of these contracts are being accounted for as incurred. The contractual obligations table above does not include long-term commitments signed by CL&P and NSTAR Electric, as required by the PURA and the DPU, respectively, for the purchase of renewable energy and related products that are contingent on the future construction of energy facilities, such as the long-term commitments of NSTAR Electric pertaining to the Massachusetts Clean Energy 83D contract entered into in 2018. Natural Gas Procurement: Eversource's natural gas distribution businesses have long-term contracts for the purchase, transportation and storage of natural gas as part of its portfolio of supplies, which extend through 2045. Purchased Power and Capacity: These contracts include capacity CfDs with generation facilities at CL&P through 2026, and various IPP contracts or purchase obligations for electricity which extend through 2024 for CL&P and 2031 for NSTAR Electric. CL&P's portion of the costs and benefits under these capacity contracts are recovered from, or refunded to, CL&P's customers. Peaker CfDs: CL&P, along with UI, has three peaker CfDs for a total of approximately 500 MW of peaking capacity through 2042. CL&P has a sharing agreement with UI, whereby CL&P is responsible for 80 percent and UI for 20 percent of the net costs or benefits of these CfDs. The Peaker CfDs pay the generation facility owner the difference between capacity, forward reserve and energy market revenues and a cost-of-service payment stream for 30 years. The ultimate cost or benefit to CL&P under these contracts will depend on the costs of plant operation and the prices that the projects receive for capacity and other products in the ISO-NE markets. CL&P's portion of the amounts paid or received under the Peaker CfDs are recovered from, or refunded to, CL&P's customers. Transmission Support Commitments: Along with other New England utilities, CL&P, NSTAR Electric and PSNH have entered into agreements to support the costs of, and receive rights to use, transmission and terminal facilities that import electricity from the Hydro-Québec system in Canada. CL&P, NSTAR Electric and PSNH are obligated to pay, over a 20-year period ending in 2040, their proportionate shares of the annual operation and maintenance expenses and capital costs of those facilities. The total costs incurred under these agreements were as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Renewable Energy Purchase Contracts $ 581.4 $ 678.1 $ 609.2 Natural Gas Procurement 695.8 1,042.8 712.7 Purchased Power and Capacity 69.0 61.6 56.4 Peaker CfDs 20.1 13.4 24.3 Transmission Support Commitments 14.2 12.7 15.4 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Renewable Energy Purchase Contracts $ 474.1 $ 60.0 $ 47.3 $ 513.2 $ 90.8 $ 74.1 $ 457.1 $ 84.7 $ 67.4 Purchased Power and Capacity 65.5 2.9 0.6 57.7 3.0 0.9 53.1 3.0 0.3 Peaker CfDs 20.1 — — 13.4 — — 24.3 — — Transmission Support Commitments 5.6 5.6 3.0 5.0 5.0 2.7 6.1 6.0 3.3 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, III and IV of litigation resulting from the DOE's failure to meet its contractual obligations. These Phases covered damages incurred in the years 1998 through 2016, and the awarded damages have been received by the Yankee Companies with certain amounts of the damages refunded to their customers. DOE Phase V Damages - On March 25, 2021, each of the Yankee Companies filed a fifth set of lawsuits against the DOE in the Court of Federal Claims resulting from the DOE's failure to begin accepting spent nuclear fuel for disposal covering the years from 2017 to 2020. The Yankee Companies filed claims seeking monetary damages totaling $120.4 million for CYAPC, YAEC and MYAPC. Pursuant to a June 2, 2022 court order, the Yankee Companies were subsequently permitted to include monetary damages relating to the year 2021 in the DOE Phase V complaint. The Yankee Companies submitted a supplemental filing to include these costs of $33.1 million on June 8, 2022. The DOE Phase V trial is expected to begin in the spring of 2024. D. 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. Guarantees issued on behalf of unconsolidated entities, including equity method offshore wind investments, for which Eversource parent is the guarantor, are recorded at fair value as a liability on the balance sheet at the inception of the guarantee. The fair value of guarantees issued on behalf of unconsolidated entities are recorded within Other Long-Term Liabilities on the balance sheet, and were $4.4 million and $4.2 million as of December 31, 2023 and 2022, respectively. Eversource regularly reviews performance risk under these guarantee arrangements, and believes the likelihood of payments being required under the guarantees is remote. 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. The following table summarizes Eversource parent's exposure to guarantees and indemnifications of its subsidiaries and affiliates to external parties, and primarily relates to its offshore wind business: As of December 31, 2023 Company (Obligor) Description Maximum Exposure North East Offshore, LLC, Sunrise Wind LLC, Revolution Wind, LLC and South Fork Wind, LLC Offshore wind construction-related purchase agreements with third-party contractors (1) $ 1,941.1 Eversource Investment LLC and South Fork Class B Member, LLC Funding and indemnification obligations of South Fork Wind and North East Offshore, LLC (2) 485.9 Sunrise Wind LLC OREC capacity production (3) 11.0 South Fork Wind, LLC Power Purchase Agreement Security (4) 7.1 Eversource Investment LLC Letters of Credit (5) 15.2 Eversource TEI LLC South Fork Wind Tax Equity (6) — Various Surety bonds (7) 38.8 Sunrise Wind LLC Surety bonds (8) 20.5 (1) Eversource parent issued guarantees on behalf of its 50 percent-owned affiliates, North East Offshore, LLC (NEO), Sunrise Wind LLC, Revolution Wind, LLC and South Fork Wind, LLC, under which Eversource parent agreed to guarantee each entity’s performance of obligations under certain construction-related purchase agreements with third-party contractors, in an aggregate amount not to exceed $3.03 billion. Eversource parent’s obligations under the guarantees expire upon the earlier of (i) dates ranging between May 2024 and October 2028 and (ii) full performance of the guaranteed obligations. Eversource parent also issued a separate guarantee to Ørsted on behalf of NEO, under which Eversource parent agreed to guarantee 50 percent of NEO’s payment obligations under certain offshore wind project construction-related agreements with Ørsted in an aggregate amount not to exceed $62.5 million and expiring upon full performance of the guaranteed obligation. (2) Eversource parent issued guarantees on behalf of its wholly-owned subsidiary Eversource Investment LLC (EI), which holds Eversource's investments in offshore wind-related equity method investments, and on behalf of its 50 percent-owned affiliate, South Fork Class B Member, LLC, whereby Eversource parent will guarantee each entity’s performance of certain capital expenditure funding obligations during the construction phases of the South Fork Wind project and NEO’s underlying offshore wind projects. Eversource parent also guaranteed certain indemnification obligations of EI associated with third party credit support for EI’s investment in NEO. These guarantees will not exceed $1.52 billion and expire upon the full performance of the guaranteed obligations. (3) Eversource parent issued a guarantee on behalf of its 50 percent-owned affiliate, Sunrise Wind LLC, whereby Eversource parent will guarantee 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 by and between the New York State Energy Research and Development Authority (NYSERDA) and Sunrise Wind LLC. The guarantee expires upon the full performance of the guaranteed obligations. Effective January 1, 2024, the maximum exposure under the guarantee increased from $11.0 million to $15.4 million. (4) Eversource parent issued a guarantee on behalf of its 50 percent-owned affiliate, South Fork Wind, LLC, whereby Eversource parent will guarantee South Fork Wind, LLC's performance of certain obligations, in an amount not to exceed $7.1 million, under a Power Purchase Agreement between the Long Island Power Authority and South Fork Wind, LLC (the Agreement). The guarantee expires upon the later of (i) the end of the Agreement term and (ii) full performance of the guaranteed obligations. (5) Eversource parent entered into a guarantee on behalf of EI, under which Eversource parent would guarantee EI's obligations under a letter of credit facility with a financial institution that EI may request in an aggregate amount of up to approximately $25 million. As of December 31, 2023, EI has issued letters of credit on behalf of South Fork Wind, LLC, Sunrise Wind LLC and Revolution Wind, LLC totaling $15.2 million. In January 2024, EI issued two additional letters of credit on behalf of Sunrise Wind LLC totaling $8.0 million. The guarantee will remain in effect until full performance of the guaranteed obligations. (6) Eversource parent issued a guarantee on behalf of its wholly-owned subsidiary, Eversource TEI LLC, whereby Eversource parent will guarantee Eversource TEI LLC’s performance of certain obligations, in an amount not to exceed $528.4 million, primarily in connection with tax equity funding obligations during the construction phase of the South Fork Wind project. Eversource parent’s obligations expire upon the full performance of the guaranteed obligations. (7) Surety bonds expire in 2024. 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. (8) In December 2023, Sunrise Wind LLC issued a surety bond related to future decommissioning obligations of certain onshore transmission assets in the amount of $20.5 million. The surety bond shall remain outstanding until full performance of the obligations. 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, FERC issued Opinion No. 531-A and 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 both December 31, 2023 and 2022. 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 both December 31, 2023 and 2022. 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 Opinion No. 569 affecting the two pending transmission ROE complaints against the Midcontinent ISO (MISO) transmission owners, in which FERC adopted a new methodology for determining base ROEs. Various parties sought rehearing. On December 23, 2019, the NETOs filed supplementary materials in the NETOs' four pending cases to respond to this new methodology because of the uncertainty of the applicability to the NETOs' cases. On May 21, 2020, the FERC issued its order in Opinion No. 569-A on the rehearing of the MISO transmission owners' cases, in which FERC again changed its methodology for determining the MISO transmission owners' base ROEs. On November 19, 2020, the FERC issued Opinion No. 569-B denying rehearing of Opinion No. 569-A and reaffirmed the methodology previously adopted in Opinion No. 569-A. The new methodology differs significantly from the methodology proposed by FERC in its October 16, 2018 order to determine the NETOs' base ROEs in its four pending cases. FERC Opinion Nos. 569-A and 569-B were appealed to the Court. On August 9, 2022, the Court issued its decision vacating MISO ROE FERC Opinion Nos. 569, 569-A and 569-B and remanded to FERC to reopen the proceedings. The Court found that FERC’s development of the new return methodology was arbitrary and capricious due to FERC’s failure to offer a reasonable explanation for its decision to reintroduce the risk-premium financial model in its new methodology for calculating a just and reasonable return. At this time, Eversource cannot predict how and when FERC will address the Court’s findings on the remand of the MISO FERC opinions or any potential associated impact on the NETOs’ four pending ROE complaint cases. Given the significant uncertainty regarding the applicability of the FERC opinions in the MISO transmission owners’ two complaint cases to the NETOs’ pending four complaint cases, Eversource 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. As well, Eversource cannot reasonably estimate a range of loss for any of the four complaint proceedings at this time. 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. F. CL&P Regulatory Matters CL&P Tropical Storm Isaias Response Investigation: On April 28, 2021, PURA issued a final decision on CL&P’s compliance with its emergency response plan that concluded CL&P failed to comply with certain storm performance standards and was imprudent in certain instances regarding its preparation for, and response to, Tropical Storm Isaias. Based on its findings, PURA ordered CL&P to adjust its future rates in a pending or future rate proceeding to reflect a monetary penalty in the form of a downward adjustment of 90 basis points in its allowed rate of return on equity (ROE), which is currently 9.25 percent. On July 14, 2021, PURA issued a final decision in a penalty proceeding that included an assessment of $28.6 million, consisting of a $28.4 million civil penalty for non-compliance with storm performance standards to be provided as credits on customer bills and a $0.2 million fine for violations of accident reporting requirements to be paid to the State of Connecticut’s general fund. The $28.4 million performance penalty was credited to customers on electric bills beginning on September 1, 2021 over a one-year period. The $28.4 million is the maximum statutory penalty amount under applicable Connecticut law in effect at the time of Tropical Storm Isaias, which is 2.5 percent of CL&P’s annual distribution revenues. The liability for the performance penalty was recorded as a current regulatory liability on CL&P’s balance sheet and as a reduction to Operating Revenues on the year ended December 31, 2021 statement of income. CL&P Settlement Agreement: On October 1, 2021, CL&P entered into a settlement agreement with the DEEP, Office of Consumer Counsel, Office of the Attorney General and the Connecticut Industrial Energy Consumers, resolving certain issues that arose in then-pending regulatory proceedings initiated by PURA. PURA approved the settlement agreement on October 27, 2021. In the settlement agreement, CL&P agreed to provide a total of $65 million of customer credits, which were distributed based on customer sales over a two-month billing period from December 1, 2021 to January 31, 2022. CL&P also agreed to irrevocably set aside $10 million in a customer assistance fund to provide bill payment assistance to certain existing non-hardship and hardship customers carrying arrearages, as approved by PURA, with the objective of disbursing the funds prior to April 30, 2022. Those customers were provided with $10 million of bill forgiveness in the first quarter of 2022. CL&P recorded a current regulatory liability of $75 million on the balance sheet associated with the provisions of the settlement agreement, with a $65 million pre-tax charge as a reduction to Operating Revenues associated with the customer credits and a $10 million charge to Operations and Maintenance expense associated with the customer assistance fund on the year ended December 31, 2021 statement of income. In exchange for the $75 million of customer credits and assistance, PURA’s interim rate reduction docket was resolved without findings. As a result of the settlement agreement, neither the 90 basis point reduction to CL&P’s return on equity introduced in PURA’s storm-related decision issued April 28, 2021, nor the 45 basis point reduction to CL&P’s return on equity included in PURA’s decision issued September 14, 2021 in the interim rate reduction docket, will be implemented. CL&P also agreed to freeze its current base distribution rates, subject to the customer credits described above, until no earlier than January 1, 2024. The rate freeze applied only to base distribution rates (including storm costs) and not to other rate mechanisms such as the retail rate components, rate reconciling mechanisms, formula rates and any other adjustment mechanisms. The rate freeze also did not apply to any cost recovery mechanism outside of the base distribution rates with regard to grid-modernization initiatives or any other proceedings that were either pending or that could

LEASES

LEASES	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
LEASES	LEASES Eversource, including CL&P, NSTAR Electric and PSNH, has entered into lease agreements as a lessee for the use of land, office space, service centers, vehicles, information technology, and equipment. These lease agreements are classified as either finance or operating leases and the liability and right-of-use asset are recognized on the balance sheet at lease commencement. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term. Eversource determines whether or not a contract contains a lease based on whether or not it provides Eversource with the use of a specifically identified asset for a period of time, as well as both the right to direct the use of that asset and receive the significant economic benefits of the asset. Eversource has elected the practical expedient to not separate non-lease components from lease components and instead to account for both as a single lease component, with the exception of the information technology asset class where the lease and non-lease components are separated. The provisions of Eversource, CL&P, NSTAR Electric and PSNH lease agreements contain renewal options. The renewal options range from one year to twenty years. The renewal period is included in the measurement of the lease liability if it is reasonably certain that Eversource will exercise these renewal options. For leases entered into or modified after the January 1, 2019 implementation date of the leases standard under Topic 842, the discount rate utilized for classification and measurement purposes as of the inception date of the lease is based on each company's collateralized incremental interest rate to borrow over a comparable term for an individual lease because the rate implicit in the lease is not determinable. CL&P and PSNH entered into certain contracts for the purchase of energy that qualify as leases. These contracts do not have minimum lease payments and therefore are not recognized as a lease liability on the balance sheet and are not reflected in the future minimum lease payments table below. Expense related to these contracts is included as variable lease cost in the table below. The expense and long-term obligation for these contracts are also included in Note 13B, "Commitments and Contingencies - Long-Term Contractual Arrangements," to the financial statements. The components of lease cost, prior to amounts capitalized, are as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Finance Lease Cost: Amortization of Right-of-use-Assets $ 4.8 $ 8.3 $ 4.6 Interest on Lease Liabilities 2.0 2.0 3.9 Total Finance Lease Cost 6.8 10.3 8.5 Operating Lease Cost 11.4 11.6 12.2 Variable Lease Cost 69.2 78.1 61.0 Total Lease Cost $ 87.4 $ 100.0 $ 81.7 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Finance Lease Cost: Amortization of Right-of-use-Assets $ — $ 0.2 $ — $ — $ 0.2 $ 0.1 $ 0.5 $ 0.2 $ 0.1 Interest on Lease Liabilities — 0.6 — — 0.6 — 0.1 0.6 — Total Finance Lease Cost — 0.8 — — 0.8 0.1 0.6 0.8 0.1 Operating Lease Cost 0.7 3.0 0.4 0.3 2.3 0.1 0.3 2.3 0.1 Variable Lease Cost 21.9 — 47.3 25.6 — 52.5 16.2 — 44.8 Total Lease Cost $ 22.6 $ 3.8 $ 47.7 $ 25.9 $ 3.1 $ 52.7 $ 17.1 $ 3.1 $ 45.0 Operating lease cost, net of the capitalized portion, is included in Operations and Maintenance (or Purchased Power, Purchased Natural Gas and Transmission expense for transmission leases) on the statements of income. Amortization of finance lease assets is included in Depreciation on the statements of income. Interest expense on finance leases is included in Interest Expense on the statements of income. Supplemental balance sheet information related to leases is as follows: As of December 31, 2023 As of December 31, 2022 (Millions of Dollars) Balance Sheet Classification Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Operating Leases: Right-of-use-Assets, Net Other Long-Term Assets $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 56.9 $ 2.2 $ 22.5 $ — Operating Lease Liabilities Current Portion Other Current Liabilities $ 9.5 $ 0.8 $ 2.2 $ 1.5 $ 9.0 $ 0.6 $ 1.2 $ — Long-Term Other Long-Term Liabilities 44.0 1.4 25.5 3.2 47.9 1.6 21.3 — Total Operating Lease Liabilities $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 56.9 $ 2.2 $ 22.5 $ — Finance Leases: Right-of-use-Assets, Net Property, Plant and Equipment, Net $ 68.6 $ 18.3 $ 3.0 $ — $ 54.5 $ — $ 3.2 $ — Finance Lease Liabilities Current Portion Other Current Liabilities $ 5.4 $ 1.4 $ — $ — $ 3.8 $ — $ — $ — Long-Term Other Long-Term Liabilities 67.3 16.9 4.9 — 54.2 — 4.9 — Total Finance Lease Liabilities $ 72.7 $ 18.3 $ 4.9 $ — $ 58.0 $ — $ 4.9 $ — The finance lease payments that NSTAR Electric will make over the next twelve months are entirely interest-related, due to escalating payments. As such, none of the finance lease payments over the next twelve months will reduce the finance lease liability. Other information related to leases is as follows: As of December 31, 2023 2022 Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Weighted-Average Remaining Lease Term (Years): Operating Leases 9 4 13 3 11 4 17 — Finance Leases 13 9 18 — 15 — 19 — Weighted-Average Discount Rate (Percentage): Operating Leases 4.0 % 5.2 % 4.2 % 5.2 % 3.2 % 3.8 % 4.0 % — % Finance Leases 3.3 % 5.3 % 2.9 % — % 2.7 % — % 2.9 % — % (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2023 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 10.5 $ 0.7 $ 2.5 $ 0.4 Operating Cash Flows from Finance Leases 2.0 — 0.6 — Financing Cash Flows from Finance Leases 3.9 — — — Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 12.8 0.6 7.0 5.0 Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 18.5 18.3 — — (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2022 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 11.3 $ 0.3 $ 2.1 $ 0.1 Operating Cash Flows from Finance Leases 2.0 — 0.6 — Financing Cash Flows from Finance Leases 3.9 — — 0.1 Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 18.9 2.4 — — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 3.5 — — — (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2021 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 12.1 $ 0.3 $ 2.1 $ 0.1 Operating Cash Flows from Finance Leases 3.4 0.1 0.6 — Financing Cash Flows from Finance Leases 4.1 1.4 — 0.1 Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 2.1 — 1.9 — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 2.3 — — — As of December 31, 2023, lease agreements executed but not having yet commenced totaled $11.5 million for Eversource, $7 million for CL&P and $4.5 million for NSTAR Electric. These amounts are not recorded as right-of-use assets and operating lease liabilities as of December 31, 2023, but will be in 2024. Also in 2023, EGMA executed an early termination of an office space lease in connection with the purchase of the same facilities from the lessor, which reduced right-of-use assets for operating leases of Eversource by $7.5 million. Future minimum lease payments, excluding variable costs, under long-term leases, as of December 31, 2023 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric Year Ending December 31, 2024 $ 11.1 $ 0.9 $ 3.4 $ 1.7 $ 7.8 $ 1.9 $ 0.6 2025 8.3 0.9 3.0 1.7 8.2 2.3 0.7 2026 6.9 0.5 3.0 1.5 7.8 2.4 0.7 2027 4.3 — 2.3 0.1 7.9 2.5 0.7 2028 4.3 — 2.4 — 7.2 2.6 0.7 Thereafter 30.3 — 24.6 — 57.8 11.5 11.0 Future lease payments 65.2 2.3 38.7 5.0 96.7 23.2 14.4 Less amount representing interest 11.7 0.1 11.0 0.3 24.0 4.9 9.5 Present value of future minimum lease payments $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 72.7 $ 18.3 $ 4.9
LEASES	LEASES Eversource, including CL&P, NSTAR Electric and PSNH, has entered into lease agreements as a lessee for the use of land, office space, service centers, vehicles, information technology, and equipment. These lease agreements are classified as either finance or operating leases and the liability and right-of-use asset are recognized on the balance sheet at lease commencement. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term. Eversource determines whether or not a contract contains a lease based on whether or not it provides Eversource with the use of a specifically identified asset for a period of time, as well as both the right to direct the use of that asset and receive the significant economic benefits of the asset. Eversource has elected the practical expedient to not separate non-lease components from lease components and instead to account for both as a single lease component, with the exception of the information technology asset class where the lease and non-lease components are separated. The provisions of Eversource, CL&P, NSTAR Electric and PSNH lease agreements contain renewal options. The renewal options range from one year to twenty years. The renewal period is included in the measurement of the lease liability if it is reasonably certain that Eversource will exercise these renewal options. For leases entered into or modified after the January 1, 2019 implementation date of the leases standard under Topic 842, the discount rate utilized for classification and measurement purposes as of the inception date of the lease is based on each company's collateralized incremental interest rate to borrow over a comparable term for an individual lease because the rate implicit in the lease is not determinable. CL&P and PSNH entered into certain contracts for the purchase of energy that qualify as leases. These contracts do not have minimum lease payments and therefore are not recognized as a lease liability on the balance sheet and are not reflected in the future minimum lease payments table below. Expense related to these contracts is included as variable lease cost in the table below. The expense and long-term obligation for these contracts are also included in Note 13B, "Commitments and Contingencies - Long-Term Contractual Arrangements," to the financial statements. The components of lease cost, prior to amounts capitalized, are as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Finance Lease Cost: Amortization of Right-of-use-Assets $ 4.8 $ 8.3 $ 4.6 Interest on Lease Liabilities 2.0 2.0 3.9 Total Finance Lease Cost 6.8 10.3 8.5 Operating Lease Cost 11.4 11.6 12.2 Variable Lease Cost 69.2 78.1 61.0 Total Lease Cost $ 87.4 $ 100.0 $ 81.7 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Finance Lease Cost: Amortization of Right-of-use-Assets $ — $ 0.2 $ — $ — $ 0.2 $ 0.1 $ 0.5 $ 0.2 $ 0.1 Interest on Lease Liabilities — 0.6 — — 0.6 — 0.1 0.6 — Total Finance Lease Cost — 0.8 — — 0.8 0.1 0.6 0.8 0.1 Operating Lease Cost 0.7 3.0 0.4 0.3 2.3 0.1 0.3 2.3 0.1 Variable Lease Cost 21.9 — 47.3 25.6 — 52.5 16.2 — 44.8 Total Lease Cost $ 22.6 $ 3.8 $ 47.7 $ 25.9 $ 3.1 $ 52.7 $ 17.1 $ 3.1 $ 45.0 Operating lease cost, net of the capitalized portion, is included in Operations and Maintenance (or Purchased Power, Purchased Natural Gas and Transmission expense for transmission leases) on the statements of income. Amortization of finance lease assets is included in Depreciation on the statements of income. Interest expense on finance leases is included in Interest Expense on the statements of income. Supplemental balance sheet information related to leases is as follows: As of December 31, 2023 As of December 31, 2022 (Millions of Dollars) Balance Sheet Classification Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Operating Leases: Right-of-use-Assets, Net Other Long-Term Assets $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 56.9 $ 2.2 $ 22.5 $ — Operating Lease Liabilities Current Portion Other Current Liabilities $ 9.5 $ 0.8 $ 2.2 $ 1.5 $ 9.0 $ 0.6 $ 1.2 $ — Long-Term Other Long-Term Liabilities 44.0 1.4 25.5 3.2 47.9 1.6 21.3 — Total Operating Lease Liabilities $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 56.9 $ 2.2 $ 22.5 $ — Finance Leases: Right-of-use-Assets, Net Property, Plant and Equipment, Net $ 68.6 $ 18.3 $ 3.0 $ — $ 54.5 $ — $ 3.2 $ — Finance Lease Liabilities Current Portion Other Current Liabilities $ 5.4 $ 1.4 $ — $ — $ 3.8 $ — $ — $ — Long-Term Other Long-Term Liabilities 67.3 16.9 4.9 — 54.2 — 4.9 — Total Finance Lease Liabilities $ 72.7 $ 18.3 $ 4.9 $ — $ 58.0 $ — $ 4.9 $ — The finance lease payments that NSTAR Electric will make over the next twelve months are entirely interest-related, due to escalating payments. As such, none of the finance lease payments over the next twelve months will reduce the finance lease liability. Other information related to leases is as follows: As of December 31, 2023 2022 Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Weighted-Average Remaining Lease Term (Years): Operating Leases 9 4 13 3 11 4 17 — Finance Leases 13 9 18 — 15 — 19 — Weighted-Average Discount Rate (Percentage): Operating Leases 4.0 % 5.2 % 4.2 % 5.2 % 3.2 % 3.8 % 4.0 % — % Finance Leases 3.3 % 5.3 % 2.9 % — % 2.7 % — % 2.9 % — % (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2023 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 10.5 $ 0.7 $ 2.5 $ 0.4 Operating Cash Flows from Finance Leases 2.0 — 0.6 — Financing Cash Flows from Finance Leases 3.9 — — — Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 12.8 0.6 7.0 5.0 Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 18.5 18.3 — — (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2022 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 11.3 $ 0.3 $ 2.1 $ 0.1 Operating Cash Flows from Finance Leases 2.0 — 0.6 — Financing Cash Flows from Finance Leases 3.9 — — 0.1 Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 18.9 2.4 — — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 3.5 — — — (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2021 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 12.1 $ 0.3 $ 2.1 $ 0.1 Operating Cash Flows from Finance Leases 3.4 0.1 0.6 — Financing Cash Flows from Finance Leases 4.1 1.4 — 0.1 Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 2.1 — 1.9 — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 2.3 — — — As of December 31, 2023, lease agreements executed but not having yet commenced totaled $11.5 million for Eversource, $7 million for CL&P and $4.5 million for NSTAR Electric. These amounts are not recorded as right-of-use assets and operating lease liabilities as of December 31, 2023, but will be in 2024. Also in 2023, EGMA executed an early termination of an office space lease in connection with the purchase of the same facilities from the lessor, which reduced right-of-use assets for operating leases of Eversource by $7.5 million. Future minimum lease payments, excluding variable costs, under long-term leases, as of December 31, 2023 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric Year Ending December 31, 2024 $ 11.1 $ 0.9 $ 3.4 $ 1.7 $ 7.8 $ 1.9 $ 0.6 2025 8.3 0.9 3.0 1.7 8.2 2.3 0.7 2026 6.9 0.5 3.0 1.5 7.8 2.4 0.7 2027 4.3 — 2.3 0.1 7.9 2.5 0.7 2028 4.3 — 2.4 — 7.2 2.6 0.7 Thereafter 30.3 — 24.6 — 57.8 11.5 11.0 Future lease payments 65.2 2.3 38.7 5.0 96.7 23.2 14.4 Less amount representing interest 11.7 0.1 11.0 0.3 24.0 4.9 9.5 Present value of future minimum lease payments $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 72.7 $ 18.3 $ 4.9

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2023
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 Fair Carrying Fair Carrying Fair As of December 31, 2023: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 122.2 $ 116.2 $ 90.4 $ 43.0 $ 31.8 $ — $ — Long-Term Debt 24,413.5 22,855.2 4,814.4 4,572.0 4,496.9 4,273.7 1,431.6 1,292.6 Rate Reduction Bonds 410.5 395.0 — — — — 410.5 395.0 As of December 31, 2022: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 136.7 $ 116.2 $ 99.2 $ 43.0 $ 37.5 $ — $ — Long-Term Debt 21,044.1 18,891.3 4,216.5 3,828.3 4,425.1 4,091.8 1,164.6 970.5 Rate Reduction Bonds 453.7 424.7 — — — — 453.7 424.7 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 1G, "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)	12 Months Ended
	Dec. 31, 2023
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 Year Ended December 31, 2023 For the Year Ended December 31, 2022 Eversource (Millions of Dollars) Qualified Unrealized Defined Total Qualified Unrealized Defined Total Balance as of January 1st $ (0.4) $ (1.2) $ (37.8) $ (39.4) $ (0.4) $ 0.4 $ (42.3) $ (42.3) OCI Before Reclassifications — — (8.8) (8.8) — (1.6) (2.5) (4.1) Amounts Reclassified from AOCI — 1.2 13.3 14.5 — — 7.0 7.0 Net OCI — 1.2 4.5 5.7 — (1.6) 4.5 2.9 Balance as of December 31st $ (0.4) $ — $ (33.3) $ (33.7) $ (0.4) $ (1.2) $ (37.8) $ (39.4) 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. The related tax effects of the defined benefit plan OCI amounts before reclassifications recognized in AOCI were net deferred tax assets of $4.9 million and $1.3 million in 2023 and 2022, respectively and were net deferred tax liabilities of $8.3 million in 2021. The following table sets forth the amounts reclassified from AOCI by component and the impacted line item on the statements of income: Amounts Reclassified from AOCI Eversource (Millions of Dollars) For the Years Ended December 31, Statements of Income 2023 2022 2021 Qualified Cash Flow Hedging Instruments $ — $ — $ (1.7) Interest Expense Tax Effect — — 0.7 Income Tax Expense Qualified Cash Flow Hedging Instruments, Net of Tax — — (1.0) Unrealized Gains/(Losses) on Marketable Securities (1.6) — — Other Income, Net Tax Effect 0.4 — — Income Tax Expense Unrealized Gains/(Losses) on Marketable Securities, Net of Tax (1.2) — — Defined Benefit Plan Costs: Amortization of Actuarial Losses (7.0) (9.0) (13.1) Other Income, Net (1) Amortization of Prior Service Cost (0.3) (0.3) — Other Income, Net (1) Settlement Loss (12.4) — — Other Income, Net (1) Total Defined Benefit Plan Costs (19.7) (9.3) (13.1) Tax Effect 6.4 2.3 3.4 Income Tax Expense Defined Benefit Plan Costs, Net of Tax (13.3) (7.0) (9.7) Total Amounts Reclassified from AOCI, Net of Tax $ (14.5) $ (7.0) $ (10.7) (1) These amounts are included in the computation of net periodic Pension, SERP and PBOP costs. See Note 1K, "Summary of Significant Accounting Policies – Other Income, Net" and Note 11A, "Employee Benefits – Pension Benefits and Postretirement Benefits Other Than Pension," for further information.

DIVIDEND RESTRICTIONS

DIVIDEND RESTRICTIONS	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
DIVIDEND RESTRICTIONS	DIVIDEND RESTRICTIONS Eversource parent's ability to pay dividends may be affected by certain state statutes, the ability of its subsidiaries to pay common dividends and the leverage restriction tied to its consolidated total indebtedness to total capitalization ratio requirement in its revolving credit agreements. Pursuant to the joint revolving credit agreement of Eversource, CL&P, PSNH, NSTAR Gas, Yankee Gas, EGMA and Aquarion Water Company of Connecticut, and to the NSTAR Electric revolving credit agreement, Eversource is required to maintain consolidated total indebtedness to total capitalization ratio of no greater than 70 percent at the end of each fiscal quarter and each other company is required to maintain consolidated total indebtedness to total capitalization ratio of no greater than 65 percent at the end of each fiscal quarter. As of December 31, 2023, all companies were in compliance with suc h covenant and in compliance with all such provisions of the revolving credit agreements that may restrict the payment of dividends as of December 31, 2023. The Retained Earnings balances subject to dividend restrictions were $4.14 billion for Eversource, $2.65 billion for CL&P, $3.14 billion for NSTAR Electric and $655.8 million for PSNH as of December 31, 2023.

COMMON SHARES

COMMON SHARES	12 Months Ended
	Dec. 31, 2023
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 Par Value Authorized as of December 31, Issued as of December 31, 2023 2022 2023 2022 Eversource $ 5 410,000,000 380,000,000 359,984,073 359,984,073 CL&P $ 10 24,500,000 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 100,000,000 200 200 PSNH $ 1 100,000,000 100,000,000 301 301 Common Share Issuances and 2022 Equity Distribution Agreement: On May 11, 2022, Eversource entered into an equity distribution agreement pursuant to which it may offer and sell up to $1.2 billion of its common shares from time to time through an “at-the-market” (ATM) equity offering program. Eversource may issue and sell its common shares through its sales agents during the term of this agreement. Shares may be offered in transactions on the New York Stock Exchange, in the over-the-counter market, through negotiated transactions or otherwise. Sales may be made at either market prices prevailing at the time of sale, at prices related to such prevailing market prices or at negotiated prices. In 2023, no shares were issued under this agreement. In 2022, Eversource issued 2,165,671 common shares, which resulted in proceeds of $197.1 million, net of issuance costs. Eversource used the net proceeds received for general corporate purposes. Treasury Shares: As of December 31, 2023 and 2022, there were 10,443,807 and 11,540,218 Eversource common shares held as treasury shares, respectively. As of December 31, 2023 and 2022, there were 349,540,266 and 348,443,855 Eversource common shares outstanding, respectively. Acquisition of The Torrington Water Company: On October 3, 2022, Aquarion acquired The Torrington Water Company (TWC) following the receipt of all required approvals. The acquisition was structured as a stock-for-stock exchange, and Eversource issued 925,264 treasury shares at closing for a purchase price of $72.1 million. Acquisition of New England Service Company: On December 1, 2021, Aquarion acquired New England Service Company (NESC), pursuant to a definitive agreement entered into on April 8, 2021. The acquisition was structured as a stock-for-stock merger and Eversource issued 462,517 treasury shares at closing for a purchase price of $38.1 million. Eversource issues treasury shares to satisfy awards under the Company's incentive plans, shares issued under the dividend reinvestment and share purchase plan, and matching contributions under the Eversource 401k Plan. Eversource also issued treasury shares for its December 2021 and October 2022 water business acquisitions. The issuance of treasury shares represents a non-cash transaction, as the treasury shares were used to fulfill Eversource's obligations that require the issuance of common shares. On May 3, 2023, shareholders voted to increase the authorized common shares from 380,000,000 shares to 410,000,000 shares. Dividends on the preferred stock of CL&P and NSTAR Electric totaled $7.5 million for each of the years ended December 31, 2023, 2022 and 2021. 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 December 31, 2023 and 2022. 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.

PREFERRED STOCK NOT SUBJECT TO

PREFERRED STOCK NOT SUBJECT TO MANDATORY REDEMPTION	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
PREFERRED STOCK NOT SUBJECT TO MANDATORY REDEMPTION	PREFERRED STOCK NOT SUBJECT TO MANDATORY REDEMPTION The CL&P and NSTAR Electric preferred stock is not subject to mandatory redemption and is presented as a noncontrolling interest of a subsidiary in Eversource's financial statements. Details of preferred stock not subject to mandatory redemption are as follows (in millions, except in redemption price and shares): Redemption Price Shares Outstanding as of December 31, As of December 31, Series 2023 2022 2023 2022 CL&P $1.90 Series of 1947 $ 52.50 163,912 163,912 $ 8.2 $ 8.2 $2.00 Series of 1947 $ 54.00 336,088 336,088 16.8 16.8 $2.04 Series of 1949 $ 52.00 100,000 100,000 5.0 5.0 $2.20 Series of 1949 $ 52.50 200,000 200,000 10.0 10.0 3.90% Series of 1949 $ 50.50 160,000 160,000 8.0 8.0 $2.06 Series E of 1954 $ 51.00 200,000 200,000 10.0 10.0 $2.09 Series F of 1955 $ 51.00 100,000 100,000 5.0 5.0 4.50% Series of 1956 $ 50.75 104,000 104,000 5.2 5.2 4.96% Series of 1958 $ 50.50 100,000 100,000 5.0 5.0 4.50% Series of 1963 $ 50.50 160,000 160,000 8.0 8.0 5.28% Series of 1967 $ 51.43 200,000 200,000 10.0 10.0 $3.24 Series G of 1968 $ 51.84 300,000 300,000 15.0 15.0 6.56% Series of 1968 $ 51.44 200,000 200,000 10.0 10.0 Total CL&P 2,324,000 2,324,000 $ 116.2 $ 116.2 NSTAR Electric 4.25% Series of 1956 $ 103.625 180,000 180,000 $ 18.0 $ 18.0 4.78% Series of 1958 $ 102.80 250,000 250,000 25.0 25.0 Total NSTAR Electric 430,000 430,000 $ 43.0 $ 43.0 Fair Value Adjustment due to Merger with NSTAR (3.6) (3.6) Other 6.00% Series of 1958 $ 100.00 13 23 $ — $ — Total Eversource - Noncontrolling Interest - Preferred Stock of Subsidiaries $ 155.6 $ 155.6

COMMON SHAREHOLDERS' EQUITY AND

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS	12 Months Ended
	Dec. 31, 2023
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 Par Value Authorized as of December 31, Issued as of December 31, 2023 2022 2023 2022 Eversource $ 5 410,000,000 380,000,000 359,984,073 359,984,073 CL&P $ 10 24,500,000 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 100,000,000 200 200 PSNH $ 1 100,000,000 100,000,000 301 301 Common Share Issuances and 2022 Equity Distribution Agreement: On May 11, 2022, Eversource entered into an equity distribution agreement pursuant to which it may offer and sell up to $1.2 billion of its common shares from time to time through an “at-the-market” (ATM) equity offering program. Eversource may issue and sell its common shares through its sales agents during the term of this agreement. Shares may be offered in transactions on the New York Stock Exchange, in the over-the-counter market, through negotiated transactions or otherwise. Sales may be made at either market prices prevailing at the time of sale, at prices related to such prevailing market prices or at negotiated prices. In 2023, no shares were issued under this agreement. In 2022, Eversource issued 2,165,671 common shares, which resulted in proceeds of $197.1 million, net of issuance costs. Eversource used the net proceeds received for general corporate purposes. Treasury Shares: As of December 31, 2023 and 2022, there were 10,443,807 and 11,540,218 Eversource common shares held as treasury shares, respectively. As of December 31, 2023 and 2022, there were 349,540,266 and 348,443,855 Eversource common shares outstanding, respectively. Acquisition of The Torrington Water Company: On October 3, 2022, Aquarion acquired The Torrington Water Company (TWC) following the receipt of all required approvals. The acquisition was structured as a stock-for-stock exchange, and Eversource issued 925,264 treasury shares at closing for a purchase price of $72.1 million. Acquisition of New England Service Company: On December 1, 2021, Aquarion acquired New England Service Company (NESC), pursuant to a definitive agreement entered into on April 8, 2021. The acquisition was structured as a stock-for-stock merger and Eversource issued 462,517 treasury shares at closing for a purchase price of $38.1 million. Eversource issues treasury shares to satisfy awards under the Company's incentive plans, shares issued under the dividend reinvestment and share purchase plan, and matching contributions under the Eversource 401k Plan. Eversource also issued treasury shares for its December 2021 and October 2022 water business acquisitions. The issuance of treasury shares represents a non-cash transaction, as the treasury shares were used to fulfill Eversource's obligations that require the issuance of common shares. On May 3, 2023, shareholders voted to increase the authorized common shares from 380,000,000 shares to 410,000,000 shares. Dividends on the preferred stock of CL&P and NSTAR Electric totaled $7.5 million for each of the years ended December 31, 2023, 2022 and 2021. 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 December 31, 2023 and 2022. 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_(LOSS) PER SHARE

EARNINGS/(LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
EARNINGS/(LOSS) PER SHARE	EARNINGS/(LOSS) PER SHARE Basic earnings/(loss) per share is computed based upon the weighted average number of common shares outstanding during each period. Diluted earnings/(loss) per share is computed on the basis of the weighted average number of common shares outstanding plus the potential dilutive effect of certain share-based compensation awards as if they were converted into outstanding common shares. The dilutive effect of unvested RSU and performance share awards is calculated using the treasury stock method. RSU and performance share awards are included in basic weighted average common shares outstanding as of the date that all necessary vesting conditions have been satisfied. For the years ended December 31, 2023, 2022 and 2021, there were no antidilutive share awards excluded from the computation. The following table sets forth the components of basic and diluted earnings/(loss) per share: Eversource (Millions of Dollars, except share information) For the Years Ended December 31, 2023 2022 2021 Net (Loss)/Income Attributable to Common Shareholders $ (442.2) $ 1,404.9 $ 1,220.5 Weighted Average Common Shares Outstanding: Basic 349,580,638 346,783,444 343,972,926 Dilutive Effect 259,843 463,324 658,130 Diluted 349,840,481 347,246,768 344,631,056 Basic (Loss)/Earnings Per Common Share $ (1.27) $ 4.05 $ 3.55 Diluted (Loss)/Earnings Per Common Share $ (1.26) $ 4.05 $ 3.54

REVENUES

REVENUES	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
REVENUES	REVENUES Revenue is recognized when promised goods or services (referred to as performance obligations) are transferred to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. A five-step model is used for recognizing and measuring revenue from contracts with customers, which includes identifying the contract with the customer, identifying the performance obligations promised within the contract, determining the transaction price (the amount of consideration to which the company expects to be entitled), allocating the transaction price to the performance obligations and recognizing revenue when (or as) the performance obligation is satisfied. The following tables present operating revenues disaggregated by revenue source: For the Year Ended December 31, 2023 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 5,054.2 $ 1,145.4 $ — $ 144.7 $ — $ — $ 6,344.3 Commercial 2,893.2 637.7 — 69.8 — (4.8) 3,595.9 Industrial 352.4 186.8 — 4.5 — (19.7) 524.0 Total Retail Tariff Sales Revenues 8,299.8 1,969.9 — 219.0 — (24.5) 10,464.2 Wholesale Transmission Revenues — — 1,777.5 — — (1,310.5) 467.0 Wholesale Market Sales Revenues 625.0 206.7 — 3.9 — — 835.6 Other Revenues from Contracts with Customers 82.6 5.6 14.6 8.1 1,636.6 (1,628.0) 119.5 Amortization of Revenues Subject to Refund — — 4.3 — — — 4.3 Total Revenues from Contracts with Customers 9,007.4 2,182.2 1,796.4 231.0 1,636.6 (2,963.0) 11,890.6 Alternative Revenue Programs (54.3) 35.5 118.9 0.4 — (106.5) (6.0) Other Revenues 20.4 4.0 0.6 1.1 — — 26.1 Total Operating Revenues $ 8,973.5 $ 2,221.7 $ 1,915.9 $ 232.5 $ 1,636.6 $ (3,069.5) $ 11,910.7 For the Year Ended December 31, 2022 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 4,796.1 $ 1,204.9 $ — $ 141.7 $ — $ — $ 6,142.7 Commercial 2,903.3 648.5 — 66.5 — (4.1) 3,614.2 Industrial 374.9 199.7 — 4.7 — (20.1) 559.2 Total Retail Tariff Sales Revenues 8,074.3 2,053.1 — 212.9 — (24.2) 10,316.1 Wholesale Transmission Revenues — — 1,700.5 — — (1,264.5) 436.0 Wholesale Market Sales Revenues 1,190.9 140.8 — 3.8 — — 1,335.5 Other Revenues from Contracts with Customers 72.3 5.6 14.1 8.4 1,435.5 (1,425.3) 110.6 Amortization of/(Reserve for) Revenues 72.0 — 0.7 (0.7) — — 72.0 Total Revenues from Contracts with Customers 9,409.5 2,199.5 1,715.3 224.4 1,435.5 (2,714.0) 12,270.2 Alternative Revenue Programs (15.4) 14.8 92.7 (2.5) — (84.3) 5.3 Other Revenues 11.2 1.3 0.7 0.6 — — 13.8 Total Operating Revenues $ 9,405.3 $ 2,215.6 $ 1,808.7 $ 222.5 $ 1,435.5 $ (2,798.3) $ 12,289.3 For the Year Ended December 31, 2021 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 3,989.8 $ 1,000.3 $ — $ 133.5 $ — $ — $ 5,123.6 Commercial 2,486.1 497.6 — 62.8 — (5.1) 3,041.4 Industrial 345.3 167.2 — 4.3 — (17.1) 499.7 Total Retail Tariff Sales Revenues 6,821.2 1,665.1 — 200.6 — (22.2) 8,664.7 Wholesale Transmission Revenues — — 1,751.3 — 86.6 (1,384.7) 453.2 Wholesale Market Sales Revenues 575.8 82.1 — 3.9 — — 661.8 Other Revenues from Contracts with Customers 78.1 5.1 13.6 7.5 1,267.4 (1,257.7) 114.0 Reserve for Revenues Subject to Refund (71.1) — (5.0) (2.6) — — (78.7) Total Revenues from Contracts with Customers 7,404.0 1,752.3 1,759.9 209.4 1,354.0 (2,664.6) 9,815.0 Alternative Revenue Programs 14.7 37.0 (126.1) 1.5 — 114.6 41.7 Other Revenues 4.9 0.3 0.8 0.4 — — 6.4 Total Operating Revenues $ 7,423.6 $ 1,789.6 $ 1,634.6 $ 211.3 $ 1,354.0 $ (2,550.0) $ 9,863.1 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Revenues from Contracts with Customers Retail Tariff Sales Residential $ 2,597.8 $ 1,691.0 $ 765.4 $ 2,397.2 $ 1,601.8 $ 797.1 $ 1,994.2 $ 1,375.8 $ 619.8 Commercial 1,082.1 1,442.3 369.6 1,067.9 1,457.4 380.8 890.6 1,265.0 332.2 Industrial 137.2 123.2 92.0 146.4 135.8 92.7 131.4 119.1 94.8 Total Retail Tariff Sales Revenues 3,817.1 3,256.5 1,227.0 3,611.5 3,195.0 1,270.6 3,016.2 2,759.9 1,046.8 Wholesale Transmission Revenues 794.7 692.0 290.8 755.1 670.4 275.0 863.3 616.3 271.7 Wholesale Market Sales Revenues 429.1 131.8 64.1 873.7 215.0 102.2 408.8 109.2 57.8 Other Revenues from Contracts 32.4 49.1 18.1 30.2 46.9 11.8 26.7 56.2 11.3 Amortization of/(Reserve for) Revenues 4.3 — — 72.7 — — (76.1) — — Total Revenues from Contracts 5,077.6 4,129.4 1,600.0 5,343.2 4,127.3 1,659.6 4,238.9 3,541.6 1,387.6 Alternative Revenue Programs 66.8 (52.0) 49.8 56.5 0.7 20.1 (78.9) (15.1) (17.4) Other Revenues 9.6 8.4 3.0 1.8 7.2 2.9 0.4 3.4 1.9 Eliminations (575.2) (570.3) (204.9) (583.8) (552.1) (207.8) (523.0) (473.5) (194.9) Total Operating Revenues $ 4,578.8 $ 3,515.5 $ 1,447.9 $ 4,817.7 $ 3,583.1 $ 1,474.8 $ 3,637.4 $ 3,056.4 $ 1,177.2 Retail Tariff Sales: Regulated utilities provide products and services to their regulated customers under rates, pricing, payment terms and conditions of service, regulated by each state regulatory agency. The arrangement whereby a utility provides commodity service to a customer for a price approved by the respective state regulatory commission is referred to as a tariff sale contract, and the tariff governs all aspects of the provision of regulated services by utilities. The majority of revenue for Eversource, CL&P, NSTAR Electric and PSNH is derived from regulated retail tariff sales for the sale and distribution of electricity, natural gas and water to residential, commercial and industrial retail customers. The utility's performance obligation for the regulated tariff sales is to provide electricity, natural gas or water to the customer as demanded. The promise to provide the commodity represents a single performance obligation, as it is a promise to transfer a series of distinct goods or services that are substantially the same and that have the same pattern of transfer to the customer. Revenue is recognized over time as the customer simultaneously receives and consumes the benefits provided by the utility, and the utility satisfies its performance obligation. Revenue is recognized based on the output method as there is a directly observable output to the customer (electricity, natural gas or water units delivered to the customer and immediately consumed). Each Eversource utility is entitled to be compensated for performance completed to date (service taken by the customer) until service is terminated. In regulated tariff sales, the transaction prices are the rates approved by the respective state regulatory commissions. In general, rates can only be changed through formal proceedings with the state regulatory commissions. These rates are designed to recover the costs to provide service to customers and include a return on investment. Regulatory commission-approved tracking mechanisms are included in these rates and are also used to recover, on a fully-reconciling basis, certain costs, such as the procurement of energy supply, retail transmission charges, energy efficiency program costs, net metering for distributed generation, and restructuring and stranded costs, among others. These tracking mechanisms result in rates being changed periodically to ensure recovery of actual costs incurred and the refund of any overcollection of costs. Electric customers may elect to purchase electricity from each Eversource electric utility or may contract separately with a competitive third party supplier. Certain eligible natural gas customers may elect to purchase natural gas from each Eversource natural gas utility or may contract separately with a gas supply operator. Revenue is not recorded for the sale of the electricity or the natural gas commodity to customers who have contracted separately with these suppliers, only the delivery to a customer, as the utility is acting as an agent on behalf of the supplier. Wholesale Transmission Revenues: The Eversource electric transmission-owning companies (CL&P, NSTAR Electric and PSNH) each own and maintain transmission facilities that are part of an interstate power transmission grid over which electricity is transmitted throughout New England. CL&P, NSTAR Electric and PSNH, as well as most other New England utilities, are parties to a series of agreements that provide for coordinated planning and operation of the region's transmission facilities and the rules by which they acquire transmission services. The Eversource electric transmission-owning companies have a combination of FERC-approved regional and local formula rates that work in tandem to recover all their transmission costs. These rates are part of the ISO-NE Tariff. Regional rates recover the costs of higher voltage transmission facilities that benefit the region and are collected from all New England transmission customers, including the Eversource distribution businesses. Eversource's local rates recover the costs of transmission facilities that do not provide a benefit to the region, and are collected from Eversource's distribution businesses and other transmission customers. The distribution businesses of Eversource, in turn, recover the FERC approved charges from retail customers through annual tracking mechanisms, which are retail tariff sales. The utility's performance obligation for regulated wholesale transmission sales is to provide transmission services to the customer as demanded. The promise to provide transmission service represents a single performance obligation. The transaction prices are the transmission rate formulas as defined by the ISO-NE Tariff and are regulated and established by FERC. Wholesale transmission revenue is recognized over time as the performance obligation is completed, which occurs as transmission services are provided to customers. The revenue is recognized based on the output method. Each Eversource utility is entitled to be compensated for performance completed to date (e.g., use of the transmission system by the customer). Wholesale Market Sales Revenues: Wholesale market sales transactions include sales of energy and energy-related products into the ISO-NE wholesale electricity market, sales of natural gas to third party marketers, and also the sale of RECs to various counterparties. ISO-NE oversees the region's wholesale electricity market and administers the transactions and terms and conditions, including payment terms, which are established in the ISO-NE tariff, between the buyers and sellers in the market. Pricing is set by the wholesale market. The wholesale transactions in the ISO-NE market occur on a day-ahead basis or a real-time basis (daily) and are, therefore, short-term. Transactions are tracked and reported by ISO-NE net by the hour, which is the net hourly position of energy sales and purchases by each market participant. The performance obligation for ISO-NE energy transactions is defined to be the net by hour transaction. Revenue is recognized when the performance obligation for these energy sales transactions is satisfied, which is when the sale occurs and the energy is transferred to the customer. For sales of natural gas, transportation, and natural gas pipeline capacity to third party marketers, revenue is recognized when the performance obligation is satisfied at the point in time the sale occurs and the natural gas or related product is transferred to the marketer. RECs are sold to various counterparties, and revenue is recognized when the performance obligation is satisfied upon transfer of title to the customer through the New England Power Pool Generation Information System. Wholesale transactions also include the sale of CL&P’s, NSTAR Electric’s and PSNH’s transmission rights associated with their proportionate equity ownership share in the transmission lines of the Hydro-Québec system in Canada. Other Revenues from Contracts with Customers: Other revenues from contracts with customers primarily include property rentals that are not deemed leases. These revenues are generally recognized on a straight-line basis over time as the service is provided to the customer. Other revenues also include revenues from Eversource's service company, which is eliminated in consolidation. Amortization of/(Reserve for) Revenues Subject to Refund: A reserve is recorded as a reduction to revenues when future refunds to customers are deemed probable. The reserve is reversed as refunds are provided to customers in rates. Amortization of Revenues Subject to Refund within the Electric Distribution segment in 2022 represents the reversal of a 2021 reserve at CL&P established to provide bill credits to customers as a result of the settlement agreement on October 1, 2021 and a storm performance penalty assessed by PURA. The reserve was reversed as customer credits were distributed to CL&P’s customers in retail electric rates. Total customer credits as a result of the 2021 settlement and civil penalty of $93.4 million were recorded as a reserve for revenues subject to refund within current regulatory liabilities and reflected as a reduction to Operating Revenues on the 2021 income statement. The settlement amount of $65 million was refunded over a two-month billing period from December 1, 2021 to January 31, 2022 and the civil penalty of $28.4 million was refunded over a one year billing period, which began September 1, 2021. Alternative Revenue Programs: In accordance with accounting guidance for rate-regulated operations, certain of Eversource's utilities' rate making mechanisms qualify as alternative revenue programs (ARPs) if they meet specified criteria, in which case revenues may be recognized prior to billing based on allowed levels of collection in rates. Eversource's utility companies recognize revenue and record a regulatory asset or liability once the condition or event allowing for the automatic adjustment of future rates occurs. ARP revenues include both the recognition of the deferral adjustment to ARP revenues, when the regulator-specified condition or event allowing for additional billing or refund has occurred, and an equal and offsetting reversal of the ARP deferral to revenues as those amounts are reflected in the price of service in subsequent periods. Eversource’s ARPs include the revenue decoupling mechanism, the annual reconciliation adjustment to transmission formula rates, and certain capital tracker mechanisms. Certain Eversource electric, natural gas and water companies, including CL&P and NSTAR Electric, have revenue decoupling mechanisms approved by a regulatory commission (decoupled companies). Decoupled companies’ distribution revenues are not directly based on sales volumes. The decoupled companies reconcile their annual base distribution rate recovery to pre-established levels of baseline distribution delivery service revenues, with any difference between the allowed level of distribution revenue and the actual amount realized adjusted through subsequent rates. The transmission formula rates provide for the annual reconciliation and recovery or refund of estimated costs to actual costs. The financial impacts of differences between actual and estimated costs are deferred for future recovery from, or refund to, transmission customers. This transmission deferral reconciles billed transmission revenues to the revenue requirement for our transmission businesses. Other Revenues: Other Revenues include certain fees charged to customers that are not considered revenue from contracts with customers. Other revenues Intercompany Eliminations: Intercompany eliminations are primarily related to the Eversource electric transmission revenues that are derived from ISO-NE regional transmission charges to the distribution businesses of CL&P, NSTAR Electric and PSNH that recover the costs of the wholesale transmission business, and revenues from Eversource's service company. Intercompany revenues and expenses between the Eversource wholesale transmission businesses and the Eversource distribution businesses and from Eversource's service company are eliminated in consolidation and included in "Eliminations" in the tables above. Receivables: Receivables, Net on the balance sheet primarily includes trade receivables from retail customers and customers related to wholesale transmission contracts, wholesale market sales, sales of RECs, and property rentals. In general, retail tariff customers and wholesale transmission customers are billed monthly and the payment terms are generally due and payable upon receipt of the bill. Unbilled Revenues: Unbilled Revenues on the balance sheet represent estimated amounts due from retail customers for electricity, natural gas or water delivered to customers but not yet billed. The utility company has satisfied its performance obligation and the customer has received and consumed the commodity as of the balance sheet date, and therefore, the utility company records revenue for those services in the period the services were provided. Only the passage of time is required before the company is entitled to payment for the satisfaction of the performance obligation. Payment from customers is due monthly as services are rendered and amounts are billed. Actual amounts billed to customers when meter readings become available may vary from the estimated amount. Unbilled revenues are recognized by allocating estimated unbilled sales volumes to the respective customer classes, and then applying an estimated rate by customer class to those sales volumes. Unbilled revenue estimates reflect seasonality, weather, customer usage patterns, customer rates in effect for customer classes, and the timing of customer billing. The companies that have a decoupling mechanism record a regulatory deferral to reflect the actual allowed amount of revenue associated with their respective decoupled distribution rate design. Practical Expedients:

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2023
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) the results of other unregulated subsidiaries, which are not part of its core business, and 5) 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 that was liquidated in 2023. In the ordinary course of business, Yankee Gas, NSTAR Gas and EGMA purchase natural gas transmission services from the Enbridge, Inc. natural gas pipeline project described above. These affiliate transaction costs total $77.7 million annually and are classified as Purchased Power, Purchased Natural Gas 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 on capital projects but not yet paid, cost of removal, AFUDC related to equity funds, and the capitalized and deferred portions of pension and PBOP income/expense. Eversource's segment information is as follows: For the Year Ended December 31, 2023 Eversource (Millions of Dollars) Electric Natural Gas Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 8,973.5 $ 2,221.7 $ 1,915.9 $ 232.5 $ 1,636.6 $ (3,069.5) $ 11,910.7 Depreciation and Amortization (18.2) (214.2) (371.2) (56.0) (158.8) 2.7 (815.7) Other Operating Expenses (8,104.6) (1,662.6) (550.5) (117.1) (1,329.8) 3,068.9 (8,695.7) Operating Income 850.7 344.9 994.2 59.4 148.0 2.1 2,399.3 Interest Expense (291.7) (85.7) (163.7) (38.5) (425.3) 149.5 (855.4) Impairments of Offshore Wind Investments — — — — (2,167.0) — (2,167.0) Interest Income 74.5 18.2 0.4 — 150.6 (149.5) 94.2 Other Income/(Loss), Net 136.2 20.4 41.2 5.9 (261.8) 312.0 253.9 Income Tax (Expense)/Benefit (157.1) (73.0) (225.8) 6.3 289.9 — (159.7) Net Income/(Loss) 612.6 224.8 646.3 33.1 (2,265.6) 314.1 (434.7) Net Income Attributable to Noncontrolling Interests (4.6) — (2.9) — — — (7.5) Net Income/(Loss) Attributable to $ 608.0 $ 224.8 $ 643.4 $ 33.1 $ (2,265.6) $ 314.1 $ (442.2) Total Assets (as of) $ 29,426.4 $ 8,775.3 $ 14,806.5 $ 2,944.8 $ 26,337.7 $ (26,678.5) $ 55,612.2 Cash Flows Used for Investments in Plant $ 1,668.1 $ 844.1 $ 1,406.3 $ 167.0 $ 251.3 $ — $ 4,336.8 For the Year Ended December 31, 2022 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Operating Revenues $ 9,405.3 $ 2,215.6 $ 1,808.7 $ 222.5 $ 1,435.5 $ (2,798.3) $ 12,289.3 Depreciation and Amortization (970.4) (157.6) (337.4) (50.9) (132.6) 5.8 (1,643.1) Other Operating Expenses (7,663.7) (1,727.0) (548.4) (111.8) (1,189.1) 2,792.0 (8,448.0) Operating Income 771.2 331.0 922.9 59.8 113.8 (0.5) 2,198.2 Interest Expense (253.1) (71.4) (145.5) (34.7) (247.8) 74.2 (678.3) Interest Income 45.1 10.2 0.5 — 66.3 (71.6) 50.5 Other Income, Net 180.4 33.6 37.9 8.5 1,600.8 (1,565.6) 295.6 Income Tax (Expense)/Benefit (146.2) (69.2) (216.3) 3.2 (25.1) — (453.6) Net Income 597.4 234.2 599.5 36.8 1,508.0 (1,563.5) 1,412.4 Net Income Attributable to Noncontrolling Interests (4.6) — (2.9) — — — (7.5) Net Income Attributable to Common Shareholders $ 592.8 $ 234.2 $ 596.6 $ 36.8 $ 1,508.0 $ (1,563.5) $ 1,404.9 Total Assets (as of) $ 27,365.0 $ 8,084.9 $ 13,369.5 $ 2,783.8 $ 26,365.2 $ (24,737.5) $ 53,230.9 Cash Flows Used for Investments in Plant $ 1,172.6 $ 710.3 $ 1,144.0 $ 154.4 $ 260.6 $ — $ 3,441.9 For the Year Ended December 31, 2021 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Operating Revenues $ 7,423.6 $ 1,789.6 $ 1,634.6 $ 211.3 $ 1,354.0 $ (2,550.0) $ 9,863.1 Depreciation and Amortization (737.8) (142.3) (300.3) (46.1) (113.1) 4.6 (1,335.0) Other Operating Expenses (5,970.0) (1,345.4) (496.2) (101.4) (1,170.4) 2,548.6 (6,534.8) Operating Income 715.8 301.9 838.1 63.8 70.5 3.2 1,993.3 Interest Expense (236.4) (58.6) (133.2) (32.0) (168.8) 46.6 (582.4) Interest Income 20.7 4.5 2.2 — 46.0 (47.8) 25.6 Other Income, Net 78.1 17.9 19.8 3.3 1,363.9 (1,347.3) 135.7 Income Tax (Expense)/Benefit (103.5) (60.9) (179.4) 1.7 (2.1) — (344.2) Net Income 474.7 204.8 547.5 36.8 1,309.5 (1,345.3) 1,228.0 Net Income Attributable to Noncontrolling Interests (4.6) — (2.9) — — — (7.5) Net Income Attributable to Common Shareholders $ 470.1 $ 204.8 $ 544.6 $ 36.8 $ 1,309.5 $ (1,345.3) $ 1,220.5 Cash Flows Used for Investments in Plant $ 1,053.3 $ 721.1 $ 1,024.1 $ 137.2 $ 239.4 $ — $ 3,175.1

GOODWILL

GOODWILL	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL	GOODWILL In a business combination, the excess of the purchase price over the estimated fair values of the assets acquired and liabilities assumed is recognized as goodwill. The following table presents Eversource’s goodwill by reportable segment: (Millions of Dollars) Electric Electric Natural Gas Water Total Balance as of January 1, 2022 $ 2,543.6 $ 576.8 $ 451.0 $ 905.9 $ 4,477.3 NESC Measurement Period Adjustments — — — 0.5 0.5 Acquisition of TWC — — — 44.8 44.8 Balance as of December 31, 2022 $ 2,543.6 $ 576.8 $ 451.0 $ 951.2 $ 4,522.6 Water Acquisitions — — — 9.5 9.5 Balance as of December 31, 2023 $ 2,543.6 $ 576.8 $ 451.0 $ 960.7 $ 4,532.1 Eversource completed the acquisition of TWC on October 3, 2022, resulting in the addition of $44.8 million of goodwill, all of which was allocated to the Water Distribution reporting unit. Eversource completed the acquisition of NESC on December 1, 2021, resulting in the addition of $22.2 million of goodwill, which included measurement period increases in 2022 totaling $0.5 million. Eversource completed two water acquisitions in 2023, resulting in the addition of $9.5 million of goodwill. The goodwill was allocated to the Water Distribution reporting unit. For further information on the acquisitions of TWC and NESC, see Note 18, “Common Shares,” to the financial statements. Goodwill is evaluated for impairment at least annually and more frequently if indicators of impairment arise. In accordance with the accounting standards, if the fair value of a reporting unit is less than its carrying value (including goodwill), the goodwill is tested for impairment. Goodwill is not subject to amortization, however is subject to a fair value based assessment for impairment at least annually and whenever facts or circumstances indicate that there may be an impairment. A resulting write-down, if any, would be charged to Operating Expenses. In assessing goodwill for impairment, an entity is permitted to first assess qualitatively whether it is more likely than not that goodwill impairment exists as of the annual impairment test date. A quantitative impairment test is required only if it is concluded that it is more likely than not that a reporting unit’s fair value is less than it’s carrying amount. The annual goodwill assessment included a qualitative evaluation of multiple factors that impact the fair value of the reporting units, including general, macroeconomic and market conditions, and entity-specific assumptions that affect the future cash flows of the reporting units. Key considerations include discount rates, utility sector market performance and merger transaction multiples, the Company's share price and credit ratings, analyst reports, financial performance, cost and risk factors, internal estimates and projections of future cash flows and net income, long-term strategy, the timing and outcome of rate cases, and recent regulatory and legislative proceedings. Eversource's reporting units for the purpose of testing goodwill are Electric Distribution, Electric Transmission, Natural Gas Distribution and Water Distribution. These reporting units are consistent with the operating segments underlying the reportable segments identified in Note 23, "Segment Information," to the financial statements.

SCHEDULE I - FINANCIAL INFORMAT

SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT	12 Months Ended
	Dec. 31, 2023
Condensed Financial Information Disclosure [Abstract]
SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT	SCHEDULE I EVERSOURCE ENERGY (PARENT) FINANCIAL INFORMATION OF REGISTRANT BALANCE SHEETS AS OF DECEMBER 31, 2023 AND 2022 (Thousands of Dollars) 2023 2022 ASSETS Current Assets: Cash $ 542 $ 971 Accounts Receivable from Subsidiaries 60,191 53,338 Notes Receivable from Subsidiaries 2,045,570 1,074,800 Prepayments and Other Current Assets 103,735 23,597 Total Current Assets 2,210,038 1,152,706 Deferred Debits and Other Assets: Investments in Subsidiary Companies, at Equity 17,977,812 18,379,840 Notes Receivable from Subsidiaries 2,296,500 1,896,500 Accumulated Deferred Income Taxes 10,131 — Goodwill 3,852,524 3,852,524 Other Long-Term Assets 28,287 108,867 Total Deferred Debits and Other Assets 24,165,254 24,237,731 Total Assets $ 26,375,292 $ 25,390,437 LIABILITIES AND CAPITALIZATION Current Liabilities: Notes Payable $ 1,564,575 $ 1,442,200 Long-Term Debt - Current Portion 364,653 1,207,047 Accounts Payable to Subsidiaries 38,051 33,530 Accrued Interest 106,070 72,951 Other Current Liabilities 41,268 39,856 Total Current Liabilities 2,114,617 2,795,584 Deferred Credits and Other Liabilities: Accumulated Deferred Income Taxes — 8,498 Other Long-Term Liabilities 134,432 140,393 Total Deferred Credits and Other Liabilities 134,432 148,891 Long-Term Debt 9,952,351 6,972,804 Common Shareholders' Equity: Common Shares 1,799,920 1,799,920 Capital Surplus, Paid in 8,460,876 8,401,731 Retained Earnings 4,142,515 5,527,153 Accumulated Other Comprehensive Loss (33,737) (39,421) Treasury Stock (195,682) (216,225) Common Shareholders' Equity 14,173,892 15,473,158 Total Liabilities and Capitalization $ 26,375,292 $ 25,390,437 See the Combined Notes to Financial Statements in this Annual Report on Form 10-K for a description of significant accounting matters related to Eversource parent, including Eversource common shares information as described in Note 18, "Common Shares," material obligations and guarantees as described in Note 13, "Commitments and Contingencies," and debt agreements as described in Note 8, "Short-Term Debt," and Note 9, "Long-Term Debt." SCHEDULE I EVERSOURCE ENERGY (PARENT) FINANCIAL INFORMATION OF REGISTRANT STATEMENTS OF (LOSS)/INCOME FOR THE YEARS ENDED DECEMBER 31, 2023, 2022 AND 2021 (Thousands of Dollars, Except Share Information) 2023 2022 2021 Operating Revenues $ 840 $ — $ — Operating Expenses: Other 12,769 26,708 43,048 Operating Loss (11,929) (26,708) (43,048) Interest Expense 397,281 237,773 163,613 Other Income, Net: Equity in (Losses)/Earnings of Subsidiaries (312,040) 1,565,474 1,345,199 Other, Net 188,003 79,383 47,802 Other (Loss)/Income, Net (124,037) 1,644,857 1,393,001 (Loss)/Income Before Income Tax Benefit (533,247) 1,380,376 1,186,340 Income Tax Benefit (91,007) (24,499) (34,187) Net (Loss)/Income $ (442,240) $ 1,404,875 $ 1,220,527 Basic (Loss)/Earnings per Common Share $ (1.27) $ 4.05 $ 3.55 Diluted (Loss)/Earnings per Common Share $ (1.26) $ 4.05 $ 3.54 Weighted Average Common Shares Outstanding: Basic 349,580,638 346,783,444 343,972,926 Diluted 349,840,481 347,246,768 344,631,056 STATEMENTS OF COMPREHENSIVE (LOSS)/INCOME (Thousands of Dollars) 2023 2022 2021 Net (Loss)/Income $ (442,240) $ 1,404,875 $ 1,220,527 Other Comprehensive Income, Net of Tax: Qualified Cash Flow Hedging Instruments 20 20 972 Changes in Unrealized Gains/(Losses) on Marketable Securities 1,252 (1,636) (671) Changes in Funded Status of Pension, SERP and PBOP Benefit Plans 4,412 4,470 33,835 Other Comprehensive Income, Net of Tax 5,684 2,854 34,136 Comprehensive (Loss)/Income $ (436,556) $ 1,407,729 $ 1,254,663 See the Combined Notes to Financial Statements in this Annual Report on Form 10-K for a description of significant accounting matters related to Eversource parent, including Eversource common shares information as described in Note 18, "Common Shares," material obligations and guarantees as described in Note 13, "Commitments and Contingencies," and debt agreements as described in Note 8, "Short-Term Debt," and Note 9, "Long-Term Debt." SCHEDULE I EVERSOURCE ENERGY (PARENT) FINANCIAL INFORMATION OF REGISTRANT STATEMENTS OF CASH FLOWS FOR THE YEARS ENDED DECEMBER 31, 2023, 2022 and 2021 (Thousands of Dollars) 2023 2022 2021 Operating Activities: Net (Loss)/Income $ (442,240) $ 1,404,875 $ 1,220,527 Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities: Equity in Losses/(Earnings) of Subsidiaries 312,040 (1,565,474) (1,345,199) Cash Dividends Received from Subsidiaries 1,027,400 855,600 1,037,100 Deferred Income Taxes (22,256) 25,823 20,293 Other (12,834) 26,455 36,910 Changes in Current Assets and Liabilities: Accounts Receivables from Subsidiaries (6,853) (9,935) (3,758) Taxes Receivable/Accrued, Net (80,968) (21,627) (19,455) Accounts Payable to Subsidiaries 4,521 (4,079) 19,185 Other Current Assets and Liabilities, Net 35,357 35,090 8,144 Net Cash Flows Provided by Operating Activities 814,167 746,728 973,747 Investing Activities: Capital Contributions to Subsidiaries (1,369,700) (1,499,300) (1,033,000) Return of Capital from Subsidiaries 438,000 12,000 178,800 Increase in Notes Receivable from Subsidiaries (1,578,100) (724,400) (140,200) Other Investing Activities 147,567 (1,289) (3,196) Net Cash Flows Used in Investing Activities (2,362,233) (2,212,989) (997,596) Financing Activities: Issuance of Common Shares, Net of Issuance Costs — 197,058 — Cash Dividends on Common Shares (918,995) (860,033) (805,439) Issuance of Long-Term Debt 3,350,000 2,800,000 1,000,000 Retirement of Long-Term Debt (1,200,000) (750,000) (450,000) Increase in Notes Payable 329,705 99,250 288,625 Other Financing Activities (13,076) (19,193) (9,545) Net Cash Flows Provided by Financing Activities 1,547,634 1,467,082 23,641 Net (Decrease)/Increase in Cash and Restricted Cash (432) 821 (208) Cash and Restricted Cash - Beginning of Year 1,047 226 434 Cash and Restricted Cash - End of Year $ 615 $ 1,047 $ 226 Supplemental Cash Flow Information: Cash Paid/(Received) During the Year for: Interest $ 366,645 $ 215,053 $ 164,568 Income Taxes $ 23,984 $ (20,992) $ (51,277) See the Combined Notes to Financial Statements in this Annual Report on Form 10-K for a description of significant accounting matters related to Eversource parent, including Eversource common shares information as described in Note 18, "Common Shares," material obligations and guarantees as described in Note 13, "Commitments and Contingencies," and debt agreements as described in Note 8, "Short-Term Debt," and Note 9, "Long-Term Debt."

SCHEDULE II - VALUATION AND QUA

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	SCHEDULE II EVERSOURCE ENERGY AND SUBSIDIARIES VALUATION AND QUALIFYING ACCOUNTS AND RESERVES FOR THE YEARS ENDED DECEMBER 31, 2023, 2022 AND 2021 (Thousands of Dollars) Column A Column B Column C Column D Column E Additions (1) (2) Description: Balance as of Beginning of Year Charged to Costs and Expenses Charged to Other Deductions -Describe (b) Balance as of End of Year Eversource : Reserves Deducted from Assets - Reserves for Uncollectible Accounts: 2023 $ 486,297 $ 72,468 $ 158,205 $ 162,515 $ 554,455 2022 417,406 61,876 112,533 105,518 486,297 2021 358,851 60,886 110,572 112,903 417,406 CL&P: Reserves Deducted from Assets - Reserves for Uncollectible Accounts: 2023 $ 225,320 $ 11,675 $ 126,360 $ 67,325 $ 296,030 2022 181,319 15,578 59,485 31,062 225,320 2021 157,447 13,495 57,779 47,402 181,319 NSTAR Electric: Reserves Deducted from Assets - Reserves for Uncollectible Accounts: 2023 $ 94,958 $ 22,791 $ 17,488 $ 38,211 $ 97,026 2022 97,005 21,550 12,412 36,009 94,958 2021 91,583 16,649 20,064 31,291 97,005 PSNH : Reserves Deducted from Assets - Reserves for Uncollectible Accounts: 2023 $ 29,236 $ 3,989 $ (8,735) $ 10,168 $ 14,322 2022 24,331 9,211 2,539 6,845 29,236 2021 17,157 13,113 3,135 9,074 24,331 (a) Amounts relate to uncollectible accounts receivables reserved for that are not charged to bad debt expense. CL&P, NSTAR Electric, NSTAR Gas, EGMA and Yankee Gas are allowed to recover in rates, amounts associated with certain uncollectible hardship accounts receivable. CL&P, NSTAR Electric, PSNH, NSTAR Gas and EGMA are also allowed to recover uncollectible energy supply costs through regulatory tracking mechanisms.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net (Loss)/Income	$ (434.7)	$ 1,412.4	$ 1,228

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The 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 consolidated financial statements of Eversource, NSTAR Electric and PSNH and the financial statements of CL&P are herein collectively referred to as the "financial statements." 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. CYAPC and YAEC are inactive regional nuclear power companies engaged in the long-term storage of their spent nuclear fuel. Eversource consolidates the operations of 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, including 50 percent ownership interests in three offshore wind projects and a tax equity investment in one of the projects. See Note 6, “Investments in Unconsolidated Affiliates,” for further information on Eversource’s equity method investments and impairment charges recorded in 2023 to the offshore wind investments carrying value. In accordance with accounting guidance on noncontrolling interests in consolidated financial statements, the Preferred Stock of CL&P and the Preferred Stock of NSTAR Electric, which are not owned by Eversource or its consolidated subsidiaries and are not subject to mandatory redemption, have been presented as noncontrolling interests in the financial statements of Eversource. The Preferred Stock of CL&P and the Preferred Stock of NSTAR Electric are considered to be temporary equity and have been classified between liabilities and permanent shareholders' equity on the balance sheets of Eversource, CL&P and NSTAR Electric due to a provision in the preferred stock agreements of both CL&P and NSTAR Electric that grant preferred stockholders the right to elect a majority of the CL&P and NSTAR Electric Boards of Directors, respectively, should certain conditions exist, such as if preferred dividends are in arrears for a specified amount of time. The Net Income reported in the statements of income and cash flows represents net income prior to apportionment to noncontrolling interests, which is represented by dividends on preferred stock of CL&P and NSTAR Electric.
Cash and Cash Equivalents	Cash and Cash EquivalentsCash includes cash on hand. At the end of each reporting period, any overdraft amounts are reclassified from Cash to Accounts Payable on the balance sheets. Cash Equivalents include short-term cash investments that are highly liquid in nature and have original maturities of three months or less.
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts Receivables, Net on the balance sheets primarily includes 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). The current expected credit loss (CECL) model is 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 an aging-based quantitative assessment that applies an estimated uncollectible percentage to each receivable aging category. Factors in determining credit loss include historical collection, write-off experience, analysis of delinquency statistics, and management's assessment of collectability from customers, including current economic conditions, customer payment trends, the impact on customer bills because of energy usage trends and changes in rates, flexible payment plans and financial hardship arrearage management programs offered to customers, reasonable forecasts, and expectations of future collectability and collection efforts. Management continuously assesses the collectability of receivables and adjusts estimates based on actual experience and future expectations based on economic conditions, collection efforts and other factors. 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. Management concluded that the reserve balance as of December 31, 2023 adequately reflected the collection risk and net realizable value for its receivables.
Transfer of Energy Efficiency Loans	Transfer of Energy Efficiency LoansCL&P transferred a portion of its energy efficiency customer loan portfolio to outside lenders in order to make additional loans to customers.  CL&P remains the servicer of the loans and will transmit customer payments to the lenders, with a maximum amount outstanding under this program of $55 million.  The amounts of the loans are included in Receivables, Net and Other Long-Term Assets, and are offset by Other Current Liabilities and Other Long-Term Liabilities on CL&P’s balance sheet.
Materials, Supplies, Natural Gas and REC Inventory	Materials, Supplies, Natural Gas and REC InventoryMaterials, Supplies, Natural Gas and REC Inventory include materials and supplies purchased primarily for construction or operation and maintenance purposes, natural gas purchased for delivery to customers, and RECs.  Inventory is valued at the lower of cost or net realizable value. RECs are purchased from suppliers of renewable sources of generation and are used to meet state mandated Renewable Portfolio Standards requirements.
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 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, equity method investments, AROs, and in the valuation of business combinations and asset acquisitions. The fair value measurement guidance was also applied in estimating the 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 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," Note 6, "Investments in Unconsolidated Affiliates," Note 7, "Asset Retirement Obligations," Note 11A, "Employee Benefits – Pension Benefits and Postretirement Benefits Other Than Pension," Note 15, "Fair Value of Financial Instruments," and Note 24, “Goodwill,” to the financial statements.
Derivative Accounting	Derivative Accounting Many of the electric and natural gas companies' contracts for the purchase and sale of energy or energy-related products are derivatives. The accounting treatment for energy contracts entered into varies and depends on the intended use of the particular contract and on whether or not the contract is a derivative. The application of derivative accounting is complex and requires management judgment in the following respects: identification of derivatives and embedded derivatives, election and designation of a contract as normal, and determination of the fair value of derivative contracts. All of these judgments can have a significant impact on the financial statements. The judgment applied in the election of a contract as normal (and resulting accrual accounting) includes the conclusion that it is probable at the inception of the contract and throughout its term that it will result in physical delivery of the underlying product and that the quantities will be used or sold by the business in the normal course of business. If facts and circumstances change and management can no longer support this conclusion, then a contract cannot be considered normal, accrual accounting is terminated, and fair value accounting is applied prospectively. The fair value of derivative contracts is based upon the contract terms and conditions and the underlying market price or fair value per unit. When quantities are not specified in the contract, the Company determines whether the contract has a determinable quantity by using amounts referenced in default provisions and other relevant sections of the contract. The fair value of derivative assets and liabilities with the same counterparty are offset and recorded as a net derivative asset or liability on the balance sheets. Regulatory assets or regulatory liabilities are recorded to offset the fair values of these derivative contracts related to energy and energy-related products, as contract settlements are recovered from, or refunded to, customers in future rates. All changes in the fair value of these derivative contracts are recorded as regulatory assets or liabilities and do not impact net income.
Allowance for Funds Used During Construction	Allowance for Funds Used During Construction AFUDC represents the cost of borrowed and equity funds used to finance construction and is included in the cost of the electric, natural gas and water companies' utility plant on the balance sheet. The portion of AFUDC attributable to borrowed funds is recorded as a reduction of Interest Expense, and the AFUDC related to equity funds is recorded as Other Income, Net on the statements of income. AFUDC costs are recovered from customers over the service life of the related plant in the form of increased revenue collected as a result of higher depreciation expense.
Other Taxes	Other TaxesEversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers. As agents for state and local governments, Eversource's companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income.
Related Parties	Related Parties Eversource Service, Eversource's service company, provides centralized accounting, administrative, engineering, financial, information technology, legal, operational, planning, purchasing, tax, and other services to Eversource's companies. The Rocky River Realty Company and Properties, Inc., two other Eversource subsidiaries, construct, acquire or lease some of the property and facilities used by Eversource's companies. As of December 31, 2022, CL&P, NSTAR Electric and PSNH had long-term receivables from Eversource Service in the amounts of $25.0 million, $5.5 million and $3.8 million, which were included in Other Long-Term Assets on the balance sheets. These amounts related to the funding of investments held in trust by Eversource Service in connection with certain postretirement benefits for CL&P, NSTAR Electric and PSNH employees and were eliminated in consolidation on the Eversource financial statements. As of December 31, 2023, these intercompany balances were settled. Included in the CL&P, NSTAR Electric and PSNH balance sheets as of December 31, 2023 and 2022 were Accounts Receivable from Affiliated Companies and Accounts Payable to Affiliated Companies relating to transactions between CL&P, NSTAR Electric and PSNH and other subsidiaries that are wholly-owned by Eversource. These amounts have been eliminated in consolidation on the Eversource financial statements. The Eversource Energy Foundation is an independent not-for-profit charitable entity and is not included in the consolidated financial statements of Eversource as the Company does not have title to, and cannot receive contributions back from, the Eversource Energy Foundation's assets. Eversource made contributions to the Eversource Energy Foundation of $20.0 million in 2023 and $8.0 million in 2022, and did not make any contributions in 2021.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Provision for Uncollectible Accounts	The activity in the allowance for uncollectible accounts by portfolio segment is as follows: Eversource CL&P NSTAR Electric PSNH (Millions of Dollars) Hardship Accounts Retail (Non-Hardship), Total Allowance Hardship Accounts Retail (Non-Hardship), Total Allowance Hardship Accounts Retail (Non-Hardship), Total Allowance Total Allowance (2) Balance as of January 1, 2021 $ 194.8 $ 164.1 $ 358.9 $ 129.1 $ 28.3 $ 157.4 $ 39.7 $ 51.9 $ 91.6 $ 17.2 Uncollectible Expense — 60.9 60.9 — 13.5 13.5 — 16.6 16.6 13.1 Uncollectible Costs Deferred (1) 51.9 58.7 110.6 32.3 25.5 57.8 4.3 15.8 20.1 3.1 Write-Offs (22.0) (107.7) (129.7) (18.0) (36.2) (54.2) (0.7) (36.3) (37.0) (10.0) Recoveries Collected 1.4 15.3 16.7 1.2 5.6 6.8 — 5.7 5.7 0.9 Balance as of December 31, 2021 $ 226.1 $ 191.3 $ 417.4 $ 144.6 $ 36.7 $ 181.3 $ 43.3 $ 53.7 $ 97.0 $ 24.3 Uncollectible Expense — 61.9 61.9 — 15.6 15.6 — 21.6 21.6 9.2 Uncollectible Costs Deferred (1) 77.8 34.7 112.5 58.3 1.2 59.5 1.5 10.9 12.4 2.5 Write-Offs (21.3) (102.7) (124.0) (15.3) (23.0) (38.3) (1.1) (41.2) (42.3) (7.7) Recoveries Collected 1.8 16.7 18.5 1.3 5.9 7.2 — 6.3 6.3 0.9 Balance as of December 31, 2022 $ 284.4 $ 201.9 $ 486.3 $ 188.9 $ 36.4 $ 225.3 $ 43.7 $ 51.3 $ 95.0 $ 29.2 Uncollectible Expense — 72.5 72.5 — 11.7 11.7 — 22.8 22.8 4.0 Uncollectible Costs Deferred (1) 137.0 21.2 158.2 114.4 12.0 126.4 1.5 16.0 17.5 (8.7) Write-Offs (55.9) (122.2) (178.1) (44.7) (28.5) (73.2) (1.6) (41.7) (43.3) (10.9) Recoveries Collected 1.3 14.3 15.6 1.1 4.7 5.8 — 5.0 5.0 0.7 Balance as of December 31, 2023 $ 366.8 $ 187.7 $ 554.5 $ 259.7 $ 36.3 $ 296.0 $ 43.6 $ 53.4 $ 97.0 $ 14.3 (1) These expected credit losses are deferred as regulatory costs on the balance sheets, as these amounts are ultimately recovered in rates. Amounts include uncollectible costs for hardship accounts and other customer receivables, including uncollectible amounts related to uncollectible energy supply costs and COVID-19. The increase in the allowance for uncollectible hardship accounts in both 2023 and 2022 at Eversource and CL&P primarily relates to increased customer enrollment in disconnection prevention programs in Connecticut. (2) In connection with PSNH’s pole purchase agreement on May 1, 2023, the purchase price included the forgiveness of previously reserved receivables for reimbursement of operation and maintenance and vegetation management costs.
Schedule of Utility Inventory	The carrying amounts of materials and supplies, natural gas inventory, and RECs, which are included in Current Assets on the balance sheets, were as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Materials and Supplies $ 397.9 $ 156.2 $ 130.8 $ 76.5 $ 221.0 $ 88.2 $ 81.0 $ 34.4 Natural Gas 65.5 — — — 95.9 — — — RECs 43.9 0.3 43.0 0.6 57.5 — 57.4 0.1 Total $ 507.3 $ 156.5 $ 173.8 $ 77.1 $ 374.4 $ 88.2 $ 138.4 $ 34.5
Costs Related to Fuel and Natural Gas	The cost of natural gas included in Purchased Power, Purchased Natural Gas and Transmission on the statements of income were as follows: For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Eversource - Cost of Natural Gas $ 792.2 $ 1,010.2 $ 718.6
Weighted-Average AFUDC Rates	AFUDC costs and the weighted-average AFUDC rates were as follows: Eversource For the Years Ended December 31, (Millions of Dollars, except percentages) 2023 2022 2021 Borrowed Funds $ 44.6 $ 21.8 $ 18.4 Equity Funds 78.1 47.3 37.3 Total AFUDC $ 122.7 $ 69.1 $ 55.7 Average AFUDC Rate 5.8 % 4.7 % 4.2 % For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars, CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Borrowed Funds $ 7.7 $ 17.2 $ 6.1 $ 4.8 $ 10.7 $ 1.4 $ 2.9 $ 9.0 $ 0.8 Equity Funds 20.0 45.7 5.4 13.6 24.6 2.5 7.7 20.4 1.6 Total AFUDC $ 27.7 $ 62.9 $ 11.5 $ 18.4 $ 35.3 $ 3.9 $ 10.6 $ 29.4 $ 2.4 Average AFUDC Rate 6.7 % 5.9 % 5.1 % 6.6 % 5.4 % 2.6 % 5.0 % 4.9 % 2.5 %
Components of Other Income, Net	The components of Other Income, Net on the statements of income were as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion (1) $ 132.9 $ 219.8 $ 84.4 AFUDC Equity 78.1 47.3 37.3 Equity in Earnings of Unconsolidated Affiliates (2) 15.5 22.9 14.2 Investment (Loss)/Income (4.9) 1.9 (0.2) Interest Income 94.2 50.5 25.6 Other (2) 32.3 3.7 — Total Other Income, Net $ 348.1 $ 346.1 $ 161.3 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion (1) $ 34.9 $ 57.4 $ 16.2 $ 64.4 $ 85.5 $ 26.8 $ 15.2 $ 40.2 $ 10.3 AFUDC Equity 20.0 45.7 5.4 13.6 24.6 2.5 7.7 20.4 1.6 Investment (Loss)/Income (2.4) (0.2) (0.7) (1.3) 1.2 0.2 1.3 0.1 0.1 Interest Income 9.0 60.6 5.3 6.5 30.7 3.1 5.9 13.4 2.4 Other 0.1 0.6 0.4 0.1 0.7 0.1 0.1 0.7 0.2 Total Other Income, Net $ 61.6 $ 164.1 $ 26.6 $ 83.3 $ 142.7 $ 32.7 $ 30.2 $ 74.8 $ 14.6 (1) See Note 11A, "Employee Benefits – Pension Benefits and Postretirement Benefits Other Than Pension," for the components of net periodic benefit income/expense for the Pension, SERP and PBOP Plans. The non-service related components of pension, SERP and PBOP benefit income/expense, after capitalization or deferral, are presented as non-operating income and recorded in Other Income, Net on the statements of income. (2) Eversource’s equity method investment in a renewable energy fund was liquidated in March 2023. Liquidation proceeds in excess of the carrying value were recorded in 2023 within Other in the table above. See Note 6, “Investments in Unconsolidated Affiliates,” for further information. For the years ended December 31, 2022 and 2021, pre-tax income of $12.2 million and $2.1 million, respectively, associated with this investment was included in Equity in Earnings of Unconsolidated Affiliates within Other Income, Net in the table above.
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 Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Eversource $ 202.9 $ 194.7 $ 181.9 CL&P 174.9 166.1 158.1
Supplemental Cash Flow Information	Eversource (Millions of Dollars) As of and For the Years Ended December 31, 2023 2022 2021 Cash Paid During the Year for: Interest, Net of Amounts Capitalized $ 783.2 $ 636.2 $ 568.7 Income Taxes 39.2 77.9 121.6 Non-Cash Investing Activities: Plant Additions Included in Accounts Payable (As of) 564.1 586.9 467.9 As of and For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Cash Paid/(Received) During the Year for: Interest, Net of Amounts Capitalized $ 176.8 $ 182.8 $ 62.8 $ 167.2 $ 152.8 $ 58.3 $ 161.5 $ 141.6 $ 56.5 Income Taxes (44.1) 31.3 (59.9) 117.6 23.8 58.3 38.4 74.2 51.1 Non-Cash Investing Activities: Plant Additions Included in Accounts 139.8 178.9 65.9 131.8 184.3 76.2 110.6 120.0 68.7
Cash and Cash Equivalents as Reported on the Balance Sheet	As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Cash and Cash Equivalents as reported on the $ 53.9 $ 10.2 $ 6.7 $ 0.2 $ 374.6 $ 11.3 $ 327.7 $ 0.1 Restricted cash included in: Special Deposits 81.5 2.0 16.1 31.6 102.2 8.8 17.5 33.1 Marketable Securities 13.7 — — — 25.4 0.2 0.1 0.4 Other Long-Term Assets 17.3 — — 3.2 19.6 — — 3.2 Cash, Cash Equivalents and Restricted Cash $ 166.4 $ 12.2 $ 22.8 $ 35.0 $ 521.8 $ 20.3 $ 345.3 $ 36.8

REGULATORY ACCOUNTING (Tables)

REGULATORY ACCOUNTING (Tables)	12 Months Ended
	Dec. 31, 2023
Regulated Operations [Abstract]
Components of Regulatory Assets	The components of regulatory assets were as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Storm Costs, Net $ 1,785.9 $ 896.6 $ 609.1 $ 280.2 $ 1,379.1 $ 799.3 $ 484.4 $ 95.4 Regulatory Tracking Mechanisms 1,319.2 354.5 482.9 182.2 1,075.3 216.8 391.5 73.7 Benefit Costs 1,117.3 197.4 336.7 79.3 921.7 156.7 299.5 56.6 Income Taxes, Net 912.4 512.6 128.6 16.4 853.3 491.1 115.6 16.0 Securitized Stranded Costs 392.5 — — 392.5 435.7 — — 435.7 Goodwill-related 264.1 — 226.7 — 281.0 — 241.2 — Asset Retirement Obligations 137.9 38.5 72.3 4.7 127.9 35.9 68.2 4.4 Derivative Liabilities 120.9 120.9 — — 181.8 181.8 — — Other Regulatory Assets 339.0 22.7 101.6 8.0 322.5 26.2 114.0 14.4 Total Regulatory Assets 6,389.2 2,143.2 1,957.9 963.3 5,578.3 1,907.8 1,714.4 696.2 Less: Current Portion 1,674.2 480.4 676.1 189.5 1,335.5 314.1 492.8 102.2 Total Long-Term Regulatory Assets $ 4,715.0 $ 1,662.8 $ 1,281.8 $ 773.8 $ 4,242.8 $ 1,593.7 $ 1,221.6 $ 594.0
Components of Regulatory Liabilities	The components of regulatory liabilities were as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH EDIT due to Tax Cuts and Jobs Act of 2017 $ 2,548.6 $ 969.2 $ 905.1 $ 339.3 $ 2,619.3 $ 983.6 $ 944.3 $ 348.6 Cost of Removal 666.6 157.9 420.9 16.2 670.6 130.8 405.3 14.7 Regulatory Tracking Mechanisms 668.3 154.0 347.2 114.4 890.8 361.0 336.1 155.0 Deferred Portion of Non-Service Income 354.0 49.9 175.9 36.6 270.9 34.5 139.7 28.8 AFUDC - Transmission 124.3 56.1 68.2 — 98.2 48.2 50.0 — Benefit Costs 51.0 0.6 22.2 — 55.4 0.7 31.4 — Other Regulatory Liabilities 201.9 30.4 13.9 4.6 215.9 40.6 14.5 6.5 Total Regulatory Liabilities 4,614.7 1,418.1 1,953.4 511.1 4,821.1 1,599.4 1,921.3 553.6 Less: Current Portion 591.8 102.2 368.1 117.5 890.8 336.0 373.2 162.0 Total Long-Term Regulatory Liabilities $ 4,022.9 $ 1,315.9 $ 1,585.3 $ 393.6 $ 3,930.3 $ 1,263.4 $ 1,548.1 $ 391.6

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Utility Property, Plant and Equipment	The following tables summarize property, plant and equipment by asset category: Eversource As of December 31, (Millions of Dollars) 2023 2022 Distribution - Electric $ 19,656.5 $ 18,326.2 Distribution - Natural Gas 8,155.3 7,443.8 Transmission - Electric 14,666.8 13,709.3 Distribution - Water 2,280.1 2,112.6 Solar 201.1 200.8 Utility 44,959.8 41,792.7 Other (1) 2,006.8 1,738.1 Property, Plant and Equipment, Gross 46,966.6 43,530.8 Less: Accumulated Depreciation Utility (9,670.1) (9,167.4) Other (869.6) (706.1) Total Accumulated Depreciation (10,539.7) (9,873.5) Property, Plant and Equipment, Net 36,426.9 33,657.3 Construction Work in Progress 3,071.7 2,455.5 Total Property, Plant and Equipment, Net $ 39,498.6 $ 36,112.8 As of December 31, 2023 2022 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH Distribution - Electric $ 7,897.1 $ 9,000.5 $ 2,799.2 $ 7,370.1 $ 8,410.0 $ 2,586.4 Transmission - Electric 6,548.2 5,630.8 2,489.5 6,165.1 5,333.8 2,212.0 Solar — 201.1 — — 200.8 — Property, Plant and Equipment, Gross 14,445.3 14,832.4 5,288.7 13,535.2 13,944.6 4,798.4 Less: Accumulated Depreciation (2,670.5) (3,585.9) (984.0) (2,567.1) (3,381.2) (912.3) Property, Plant and Equipment, Net 11,774.8 11,246.5 4,304.7 10,968.1 10,563.4 3,886.1 Construction Work in Progress 565.4 1,507.3 270.0 498.9 1,063.6 174.1 Total Property, Plant and Equipment, Net $ 12,340.2 $ 12,753.8 $ 4,574.7 $ 11,467.0 $ 11,627.0 $ 4,060.2 (1) These assets are primarily comprised of computer software, hardware and equipment at Eversource Service and buildings at The Rocky River Realty Company. The depreciation rates for the various classes of utility property, plant and equipment aggregate to composite rates as follows: (Percent) 2023 2022 2021 Eversource 3.1 % 3.0 % 3.1 % CL&P 2.8 % 2.8 % 2.8 % NSTAR Electric 2.7 % 2.7 % 2.8 % PSNH 3.0 % 3.0 % 3.1 % The following table summarizes average remaining useful lives of depreciable assets: As of December 31, 2023 (Years) Eversource CL&P NSTAR Electric PSNH Distribution - Electric 34.0 35.3 34.5 29.6 Distribution - Natural Gas 35.7 — — — Transmission - Electric 40.6 37.1 45.3 41.4 Distribution - Water 40.0 — — — Solar 22.8 — 22.8 — Other (1) 10.4 — — — (1) The estimated useful life of computer software, hardware and equipment primarily ranges from 5 to 15 years and of buildings is 40 years.

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table presents the gross fair values of contracts, categorized by risk type, and the net amounts recorded as current or long-term derivative assets or liabilities: As of December 31, 2023 2022 CL&P (Millions of Dollars) Fair Value Hierarchy Commodity Supply Netting (1) Net Amount Fair Value Hierarchy Commodity Supply Netting (1) Net Amount Current Derivative Assets Level 2 $ 16.4 $ (0.5) $ 15.9 Level 3 $ 16.3 $ (0.5) $ 15.8 Long-Term Derivative Assets Level 2 13.6 (0.5) 13.1 Level 3 28.8 (0.9) 27.9 Current Derivative Liabilities Level 2 (81.9) — (81.9) Level 3 (81.6) — (81.6) Long-Term Derivative Liabilities Level 2 (68.0) — (68.0) Level 3 (143.9) — (143.9) (1) Amounts represent derivative assets and liabilities that Eversource elected to record net on the balance sheets. These amounts are subject to master netting agreements or similar agreements for which the right of offset exists.
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation	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 (Millions of Dollars) For the Years Ended December 31, 2023 2022 Derivatives, Net: Fair Value as of Beginning of Period $ (181.8) $ (249.2) Net Realized/Unrealized (Losses)/Gains Included in Regulatory Assets (3.9) 10.1 Settlements 64.8 57.3 Transfers out of Level 3 (1) 120.9 — Fair Value as of End of Period $ — $ (181.8) (1) Transfers out of Level 3 pertain to certain significant valuation inputs becoming observable as well as certain unobservable inputs no longer being significant to the fair value of the derivative contracts. Eversource's policy is to recognize transfers between levels of the fair value hierarchy as of the end of the reporting period.

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities Reconciliation	The following is a summary of the available-for-sale debt securities: As of December 31, 2023 2022 Eversource (Millions of Dollars) Amortized Pre-Tax Pre-Tax Fair Value Amortized Pre-Tax Pre-Tax Fair Value Debt Securities $ 169.5 $ 1.4 $ (6.6) $ 164.3 $ 201.6 $ 0.1 $ (16.2) $ 185.5
Investments Classified by Contractual Maturity Date	As of December 31, 2023, the contractual maturities of available-for-sale debt securities were as follows: Eversource (Millions of Dollars) Amortized Fair Less than one year $ 15.9 $ 15.9 One to five years 30.9 30.9 Six to ten years 38.1 37.8 Greater than ten years 84.6 79.7 Total Debt Securities $ 169.5 $ 164.3
Marketable Securities Recorded at Fair Value	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 December 31, 2023 2022 Level 1: Mutual Funds and Equities $ 176.9 $ 190.1 Money Market Funds 13.7 25.4 Total Level 1 $ 190.6 $ 215.5 Level 2: U.S. Government Issued Debt Securities (Agency and Treasury) $ 90.1 $ 82.3 Corporate Debt Securities 34.0 46.1 Asset-Backed Debt Securities 5.6 8.6 Municipal Bonds 9.8 12.7 Other Fixed Income Securities 11.1 10.4 Total Level 2 $ 150.6 $ 160.1 Total Marketable Securities $ 341.2 $ 375.6

INVESTMENTS IN UNCONSOLIDATED_2

INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Tables)	12 Months Ended
	Dec. 31, 2023
Equity Method Investments and Joint Ventures [Abstract]
Summary of Investments	Eversource's investments included the following: Investment Balance as of December 31, (Millions of Dollars) Ownership Interest 2023 2022 Offshore Wind Business 50% - 100% $ 515.5 $ 1,947.1 Natural Gas Pipeline - Algonquin Gas Transmission, LLC 15% 116.0 118.8 Renewable Energy Investment Fund 90% — 84.1 Other various 29.0 26.1 Total Investments in Unconsolidated Affiliates $ 660.5 $ 2,176.1 A summary of the significant estimates and assumptions included in the 2023 impairment charges is as follows: Second Quarter 2023 Fourth Quarter 2023 Total (Millions of Dollars) Lower expected sales proceeds across all three wind projects $ 401 $ 525 $ 926 Expected cost overruns not recovered in the sales price — 441 441 Loss of sales value from the sale price offered by GIP, including loss of ITC adders value, cancellation costs and other impacts assuming Sunrise Wind project is abandoned — 800 800 Impairment Charges, pre-tax 401 1,766 2,167 Tax Benefit (70) (144) (214) Impairment Charges, after-tax $ 331 $ 1,622 1,953 A summary of the carrying value by investee and by project as of December 31, 2023 is as follows: Investments Expected to be Disposed of Investment to be Held North East Offshore South Fork Class B Member, LLC South Fork Wind Holdings, LLC Class A Total Offshore Wind Investments (Millions of Dollars) Sunrise Wind Revolution Wind Carrying Value as of December 31, 2023, before $ 699 $ 799 $ 299 $ 485 $ 2,282 Fourth Quarter 2023 Impairment Charge (1,218) (544) — (4) (1,766) Carrying Value as of December 31, 2023 $ (519) $ 255 $ 299 $ 481 $ 516

ASSET RETIREMENT OBLIGATIONS (T

ASSET RETIREMENT OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligation	A reconciliation of the beginning and ending carrying amounts of ARO liabilities is as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Balance as of Beginning of Year $ 502.7 $ 37.4 $ 101.3 $ 4.9 $ 500.1 $ 35.0 $ 97.5 $ 4.7 Liabilities Settled During the Year (24.9) — — — (22.3) — — — Accretion 29.2 2.5 4.3 0.3 28.9 2.4 4.1 0.2 Revisions in Estimated Cash Flows (1.2) — (0.8) — (4.0) — (0.3) — Balance as of End of Year $ 505.8 $ 39.9 $ 104.8 $ 5.2 $ 502.7 $ 37.4 $ 101.3 $ 4.9

SHORT-TERM DEBT (Tables)

SHORT-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Borrowings Outstanding	The amount of borrowings outstanding and available under the commercial paper programs were as follows: Borrowings Outstanding Available Borrowing Capacity as of December 31, Weighted-Average Interest Rate as of December 31, (Millions of Dollars) 2023 2022 2023 2022 2023 2022 Eversource Parent Commercial Paper Program $ 1,771.9 $ 1,442.2 $ 228.1 $ 557.8 5.60 % 4.63 % NSTAR Electric Commercial Paper Program 365.8 — 284.2 650.0 5.40 % — % Details of long-term debt outstanding are as follows: CL&P (Millions of Dollars) As of December 31, Interest Rate 2023 2022 First Mortgage Bonds: 1994 Series D due 2024 7.875 % $ 139.8 $ 139.8 2004 Series B due 2034 5.750 % 130.0 130.0 2005 Series B due 2035 5.625 % 100.0 100.0 2006 Series A due 2036 6.350 % 250.0 250.0 2007 Series B due 2037 5.750 % 150.0 150.0 2007 Series D due 2037 6.375 % 100.0 100.0 2013 Series A due 2023 2.500 % — 400.0 2014 Series A due 2044 4.300 % 475.0 475.0 2015 Series A due 2045 4.150 % 350.0 350.0 2017 Series A due 2027 3.200 % 500.0 500.0 2018 Series A due 2048 4.000 % 800.0 800.0 2020 Series A due 2025 0.750 % 400.0 400.0 2021 Series A due 2031 2.050 % 425.0 425.0 2023 Series A due 2053 5.250 % 500.0 — 2023 Series B due 2033 4.900 % 300.0 — Total First Mortgage Bonds 4,619.8 4,219.8 Less Amounts due Within One Year (139.8) (400.0) Current Portion Classified as Long-Term Debt (1) 139.8 400.0 Commercial Paper Classified as Long-Term Debt (See Note 8, Short-Term Debt) 207.3 — Unamortized Premiums and Discounts, Net 18.0 21.5 Unamortized Debt Issuance Costs (30.7) (24.8) CL&P Long-Term Debt $ 4,814.4 $ 4,216.5 NSTAR Electric (Millions of Dollars) As of December 31, Interest Rate 2023 2022 Debentures: 2006 Debentures due 2036 5.750 % $ 200.0 $ 200.0 2010 Debentures due 2040 5.500 % 300.0 300.0 2014 Debentures due 2044 4.400 % 300.0 300.0 2015 Debentures due 2025 3.250 % 250.0 250.0 2016 Debentures due 2026 2.700 % 250.0 250.0 2017 Debentures due 2027 3.200 % 700.0 700.0 2019 Debentures due 2029 3.250 % 400.0 400.0 2020 Debentures due 2030 3.950 % 400.0 400.0 2021 Debentures due 2051 3.100 % 300.0 300.0 2021 Debentures due 2031 1.950 % 300.0 300.0 2022 Debentures due 2052 4.550 % 450.0 450.0 2022 Debentures due 2052 4.950 % 400.0 400.0 2023 Debentures due 2028 5.600 % 150.0 — Total Debentures 4,400.0 4,250.0 Notes: 2004 Senior Notes Series B due 2034 5.900 % 50.0 50.0 2007 Senior Notes Series D due 2037 6.700 % 40.0 40.0 2013 Senior Notes Series G due 2023 3.880 % — 80.0 2016 Senior Notes Series H due 2026 2.750 % 50.0 50.0 Total Notes 140.0 220.0 Less Amounts due Within One Year — (80.0) Unamortized Premiums and Discounts, Net (14.0) (14.8) Unamortized Debt Issuance Costs (29.1) (30.1) NSTAR Electric Long-Term Debt $ 4,496.9 $ 4,345.1 PSNH (Millions of Dollars) As of December 31, Interest Rate 2023 2022 First Mortgage Bonds: 2005 Series M due 2035 5.600 % $ 50.0 $ 50.0 2013 Series S due 2023 3.500 % — 325.0 2019 Series T due 2049 3.600 % 300.0 300.0 2020 Series U due 2050 2.400 % 150.0 150.0 2021 Series V due 2031 2.200 % 350.0 350.0 2023 Series W due 2053 5.150 % 300.0 — 2023 Series X due 2033 5.350 % 300.0 — Total First Mortgage Bonds 1,450.0 1,175.0 Less Amounts due Within One Year — (325.0) Current Portion Classified as Long-Term Debt (1) — 295.3 Unamortized Premiums and Discounts, Net (4.9) (2.5) Unamortized Debt Issuance Costs (13.5) (7.9) PSNH Long-Term Debt $ 1,431.6 $ 1,134.9 OTHER (Millions of Dollars) As of December 31, Interest Rate 2023 2022 Eversource Parent - Senior Notes due 2024 - 2050 0.800 % - 5.950% $ 10,300.0 $ 8,150.0 Yankee Gas - First Mortgage Bonds due 2024 - 2051 1.380 % - 5.510% 1,015.0 845.0 NSTAR Gas - First Mortgage Bonds due 2025 - 2051 2.250 % - 7.110% 705.0 705.0 EGMA - First Mortgage Bonds due 2028 - 2052 2.110 % - 5.730% 708.0 650.0 Aquarion - Senior Notes due 2024 4.000% 360.0 360.0 Aquarion - Unsecured Notes due 2028 - 2052 3.000 % - 6.430% 527.0 464.7 Aquarion - Secured Debt due 2027 - 2044 1.550 % - 9.290% 39.0 34.4 Pre-1983 Spent Nuclear Fuel Obligation (CYAPC) 12.5 11.9 Fair Value Adjustment (2) 19.3 26.2 Less Fair Value Adjustment - Current Portion (2) (5.5) (7.0) Less Amounts due in One Year (1,810.2) (1,203.4) Current Portion Classified as Long-Term Debt (1) 990.9 — Unamortized Premiums and Discounts, Net 49.7 40.1 Unamortized Debt Issuance Costs (65.0) (49.4) Total Other Long-Term Debt $ 12,845.7 $ 10,027.5 Total Eversource Long-Term Debt $ 23,588.6 $ 19,724.0 (1) As a result of the CL&P and Eversource parent long-term debt issuances in January 2024, $139.8 million and $990.9 million, respectively, of current portion of long-term debt were reclassified as Long-Term Debt on CL&P’s and Eversource parent’s balance sheets as of December 31, 2023. As a result of the CL&P and PSNH long-term debt issuances in January 2023, $400 million and $295.3 million, respectively, of current portion of long-term debt were reclassified as Long-Term Debt on CL&P’s and PSNH’s balance sheets as of December 31, 2022. (2) The fair value adjustment amount is the purchase price adjustments, net of amortization, required to record long-term debt at fair value on the dates of the 2012 merger with NSTAR and the 2017 acquisition of Aquarion.

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Outstanding Long-Term Debt	The amount of borrowings outstanding and available under the commercial paper programs were as follows: Borrowings Outstanding Available Borrowing Capacity as of December 31, Weighted-Average Interest Rate as of December 31, (Millions of Dollars) 2023 2022 2023 2022 2023 2022 Eversource Parent Commercial Paper Program $ 1,771.9 $ 1,442.2 $ 228.1 $ 557.8 5.60 % 4.63 % NSTAR Electric Commercial Paper Program 365.8 — 284.2 650.0 5.40 % — % Details of long-term debt outstanding are as follows: CL&P (Millions of Dollars) As of December 31, Interest Rate 2023 2022 First Mortgage Bonds: 1994 Series D due 2024 7.875 % $ 139.8 $ 139.8 2004 Series B due 2034 5.750 % 130.0 130.0 2005 Series B due 2035 5.625 % 100.0 100.0 2006 Series A due 2036 6.350 % 250.0 250.0 2007 Series B due 2037 5.750 % 150.0 150.0 2007 Series D due 2037 6.375 % 100.0 100.0 2013 Series A due 2023 2.500 % — 400.0 2014 Series A due 2044 4.300 % 475.0 475.0 2015 Series A due 2045 4.150 % 350.0 350.0 2017 Series A due 2027 3.200 % 500.0 500.0 2018 Series A due 2048 4.000 % 800.0 800.0 2020 Series A due 2025 0.750 % 400.0 400.0 2021 Series A due 2031 2.050 % 425.0 425.0 2023 Series A due 2053 5.250 % 500.0 — 2023 Series B due 2033 4.900 % 300.0 — Total First Mortgage Bonds 4,619.8 4,219.8 Less Amounts due Within One Year (139.8) (400.0) Current Portion Classified as Long-Term Debt (1) 139.8 400.0 Commercial Paper Classified as Long-Term Debt (See Note 8, Short-Term Debt) 207.3 — Unamortized Premiums and Discounts, Net 18.0 21.5 Unamortized Debt Issuance Costs (30.7) (24.8) CL&P Long-Term Debt $ 4,814.4 $ 4,216.5 NSTAR Electric (Millions of Dollars) As of December 31, Interest Rate 2023 2022 Debentures: 2006 Debentures due 2036 5.750 % $ 200.0 $ 200.0 2010 Debentures due 2040 5.500 % 300.0 300.0 2014 Debentures due 2044 4.400 % 300.0 300.0 2015 Debentures due 2025 3.250 % 250.0 250.0 2016 Debentures due 2026 2.700 % 250.0 250.0 2017 Debentures due 2027 3.200 % 700.0 700.0 2019 Debentures due 2029 3.250 % 400.0 400.0 2020 Debentures due 2030 3.950 % 400.0 400.0 2021 Debentures due 2051 3.100 % 300.0 300.0 2021 Debentures due 2031 1.950 % 300.0 300.0 2022 Debentures due 2052 4.550 % 450.0 450.0 2022 Debentures due 2052 4.950 % 400.0 400.0 2023 Debentures due 2028 5.600 % 150.0 — Total Debentures 4,400.0 4,250.0 Notes: 2004 Senior Notes Series B due 2034 5.900 % 50.0 50.0 2007 Senior Notes Series D due 2037 6.700 % 40.0 40.0 2013 Senior Notes Series G due 2023 3.880 % — 80.0 2016 Senior Notes Series H due 2026 2.750 % 50.0 50.0 Total Notes 140.0 220.0 Less Amounts due Within One Year — (80.0) Unamortized Premiums and Discounts, Net (14.0) (14.8) Unamortized Debt Issuance Costs (29.1) (30.1) NSTAR Electric Long-Term Debt $ 4,496.9 $ 4,345.1 PSNH (Millions of Dollars) As of December 31, Interest Rate 2023 2022 First Mortgage Bonds: 2005 Series M due 2035 5.600 % $ 50.0 $ 50.0 2013 Series S due 2023 3.500 % — 325.0 2019 Series T due 2049 3.600 % 300.0 300.0 2020 Series U due 2050 2.400 % 150.0 150.0 2021 Series V due 2031 2.200 % 350.0 350.0 2023 Series W due 2053 5.150 % 300.0 — 2023 Series X due 2033 5.350 % 300.0 — Total First Mortgage Bonds 1,450.0 1,175.0 Less Amounts due Within One Year — (325.0) Current Portion Classified as Long-Term Debt (1) — 295.3 Unamortized Premiums and Discounts, Net (4.9) (2.5) Unamortized Debt Issuance Costs (13.5) (7.9) PSNH Long-Term Debt $ 1,431.6 $ 1,134.9 OTHER (Millions of Dollars) As of December 31, Interest Rate 2023 2022 Eversource Parent - Senior Notes due 2024 - 2050 0.800 % - 5.950% $ 10,300.0 $ 8,150.0 Yankee Gas - First Mortgage Bonds due 2024 - 2051 1.380 % - 5.510% 1,015.0 845.0 NSTAR Gas - First Mortgage Bonds due 2025 - 2051 2.250 % - 7.110% 705.0 705.0 EGMA - First Mortgage Bonds due 2028 - 2052 2.110 % - 5.730% 708.0 650.0 Aquarion - Senior Notes due 2024 4.000% 360.0 360.0 Aquarion - Unsecured Notes due 2028 - 2052 3.000 % - 6.430% 527.0 464.7 Aquarion - Secured Debt due 2027 - 2044 1.550 % - 9.290% 39.0 34.4 Pre-1983 Spent Nuclear Fuel Obligation (CYAPC) 12.5 11.9 Fair Value Adjustment (2) 19.3 26.2 Less Fair Value Adjustment - Current Portion (2) (5.5) (7.0) Less Amounts due in One Year (1,810.2) (1,203.4) Current Portion Classified as Long-Term Debt (1) 990.9 — Unamortized Premiums and Discounts, Net 49.7 40.1 Unamortized Debt Issuance Costs (65.0) (49.4) Total Other Long-Term Debt $ 12,845.7 $ 10,027.5 Total Eversource Long-Term Debt $ 23,588.6 $ 19,724.0 (1) As a result of the CL&P and Eversource parent long-term debt issuances in January 2024, $139.8 million and $990.9 million, respectively, of current portion of long-term debt were reclassified as Long-Term Debt on CL&P’s and Eversource parent’s balance sheets as of December 31, 2023. As a result of the CL&P and PSNH long-term debt issuances in January 2023, $400 million and $295.3 million, respectively, of current portion of long-term debt were reclassified as Long-Term Debt on CL&P’s and PSNH’s balance sheets as of December 31, 2022. (2) The fair value adjustment amount is the purchase price adjustments, net of amortization, required to record long-term debt at fair value on the dates of the 2012 merger with NSTAR and the 2017 acquisition of Aquarion.
Schedule of Issuance and Repayments of Long-Term Debt	The following table summarizes long-term debt issuances and repayments: (Millions of Dollars) Interest Rate Issuance/ Issue Date or Repayment Date Maturity Date Use of Proceeds for Issuance/ CL&P 2023 Series A First Mortgage Bonds 5.25 % $ 500.0 January 2023 January 2053 Repaid 2013 Series A Bonds at maturity and short-term debt, and paid capital expenditures and working capital CL&P 2013 Series A First Mortgage Bonds 2.50 % (400.0) January 2023 January 2023 Paid at maturity CL&P 2023 Series B First Mortgage Bonds 4.90 % 300.0 July 2023 July 2033 Repaid short-term debt, paid capital expenditures and working capital CL&P 2024 Series A First Mortgage Bonds 4.65 % 350.0 January 2024 January 2029 Repaid short-term debt, paid capital expenditures and working capital NSTAR Electric 2023 Debentures 5.60 % 150.0 September 2023 October 2028 Repaid Series G Senior Notes at maturity and short-term debt and for general corporate purposes NSTAR Electric 2013 Series G Senior Notes 3.88 % (80.0) November 2023 November 2023 Paid at maturity PSNH Series W First Mortgage Bonds 5.15 % 300.0 January 2023 January 2053 Repaid short-term debt, paid capital expenditures and working capital PSNH Series X First Mortgage Bonds 5.35 % 300.0 September 2023 October 2033 Repaid Series S Bonds at maturity and for general corporate purposes PSNH Series S First Mortgage Bonds 3.50 % (325.0) November 2023 November 2023 Paid at maturity Eversource Parent Series Z Senior Notes 5.45 % 750.0 March 2023 March 2028 Repaid Series F Senior Notes at maturity and short-term debt Eversource Parent Series F Senior Notes 2.80 % (450.0) May 2023 May 2023 Paid at maturity Eversource Parent Series Z Senior Notes 5.45 % 550.0 May 2023 March 2028 Repaid Series T Senior Notes and Series N Senior Notes at maturity and short-term debt Eversource Parent Series AA Senior Notes 4.75 % 450.0 May 2023 May 2026 Repaid Series T Senior Notes and Series N Senior Notes at maturity and short-term debt Eversource Parent Series BB Senior Notes 5.125 % 800.0 May 2023 May 2033 Repaid Series T Senior Notes and Series N Senior Notes at maturity and short-term debt Eversource Parent Variable Rate Series T Senior Notes SOFR plus 0.25% (350.0) August 2023 August 2023 Paid at maturity Eversource Parent Series CC Senior Notes 5.95 % 800.0 November 2023 February 2029 Repaid Series N Senior Notes at maturity and short-term debt Eversource Parent Series N Senior Notes 3.80 % (400.0) December 2023 December 2023 Paid at maturity Eversource Parent Series DD Senior Notes 5.00 % 350.0 January 2024 January 2027 Repaid short-term debt Eversource Parent Series EE Senior Notes 5.50 % 650.0 January 2024 January 2034 Repaid short-term debt Yankee Gas Series V First Mortgage Bonds 5.51 % 170.0 August 2023 August 2030 Repaid short-term debt and general corporate purposes EGMA Series D First Mortgage Bonds 5.73 % 58.0 November 2023 November 2028 Repaid short-term debt, paid capital expenditures and working capital Aquarion Water Company of Connecticut Senior Notes 5.89 % 50.0 September 2023 October 2043 Repaid existing indebtedness, paid capital expenditures and general corporate purposes
Schedule of Maturities of Long-Term Debt Outstanding	Long-term debt maturities on debt outstanding for the years 2024 through 2028 and thereafter are shown below. These amounts exclude PSNH rate reduction bonds, CYAPC pre-1983 spent nuclear fuel obligation, net unamortized premiums, discounts and debt issuance costs, and other fair value adjustments as of December 31, 2023: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2024 $ 1,950.0 $ 139.8 $ — $ — 2025 1,400.2 400.0 250.0 — 2026 1,390.2 — 300.0 — 2027 2,539.2 500.0 700.0 — 2028 1,978.5 — 150.0 — Thereafter 15,005.7 3,580.0 3,140.0 1,450.0 Total $ 24,263.8 $ 4,619.8 $ 4,540.0 $ 1,450.0

RATE REDUCTION BONDS AND VARI_2

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES (Tables)	12 Months Ended
	Dec. 31, 2023
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) As of December 31, PSNH Balance Sheets: 2023 2022 Restricted Cash - Current Portion (included in Current Assets) $ 30.0 $ 32.4 Restricted Cash - Long-Term Portion (included in Other Long-Term Assets) 3.2 3.2 Securitized Stranded Cost (included in Regulatory Assets) 392.5 435.7 Other Regulatory Liabilities (included in Regulatory Liabilities) 5.3 6.0 Accrued Interest (included in Other Current Liabilities) 6.3 6.9 Rate Reduction Bonds - Current Portion 43.2 43.2 Rate Reduction Bonds - Long-Term Portion 367.3 410.5 (Millions of Dollars) PSNH Income Statements: For the Years Ended December 31, 2023 2022 2021 Amortization of RRB Principal (included in Amortization of Regulatory (Liabilities)/Assets, Net) $ 43.2 $ 43.2 $ 43.2 Interest Expense on RRB Principal (included in Interest Expense) 15.7 17.0 18.4
Schedule Of Rate Reduction Bonds, Principal And Interest Payments	Estimated principal payments on RRBs as of December 31, 2023, is summarized annually through 2028 and thereafter as follows: (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total PSNH $ 43.2 $ 43.2 $ 43.2 $ 43.2 $ 43.2 $ 194.5 $ 410.5

EMPLOYEE BENEFITS (Tables)

EMPLOYEE BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2023
Postemployment Benefits [Abstract]
Schedule of Benefit Obligations in Excess of Fair Value of Plan Assets	The following tables provide information on the plan benefit obligations, fair values of plan assets, and funded status: Pension and SERP As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Change in Benefit Obligation: Benefit Obligation as of Beginning of Year $ (5,220.1) $ (1,030.0) $ (1,110.4) $ (556.2) $ (6,729.7) $ (1,330.9) $ (1,448.4) $ (721.0) Service Cost (43.1) (12.3) (7.8) (4.3) (70.1) (18.7) (13.8) (6.9) Interest Cost (254.0) (50.5) (53.9) (27.3) (154.5) (31.3) (32.8) (16.9) Actuarial (Loss)/Gain (110.4) (19.7) (17.6) (11.6) 1,385.8 284.1 295.5 156.7 Benefits Paid - Pension 317.3 66.1 76.7 35.7 302.5 63.3 68.4 33.9 Benefits Paid - Lump Sum 28.9 — 5.3 1.0 33.0 — 14.8 1.0 Benefits Paid - SERP 43.0 0.3 0.2 0.4 12.9 0.3 0.2 0.4 Employee Transfers — (2.4) 0.5 — — 3.2 5.7 (3.4) Benefit Obligation as of End of Year $ (5,238.4) $ (1,048.5) $ (1,107.0) $ (562.3) $ (5,220.1) $ (1,030.0) $ (1,110.4) $ (556.2) Change in Pension Plan Assets: Fair Value of Pension Plan Assets as of $ 5,806.4 $ 1,172.0 $ 1,418.8 $ 618.0 $ 6,495.5 $ 1,323.8 $ 1,596.0 $ 694.6 Employer Contributions 5.0 — — — 80.0 — 15.0 — Actual Return on Pension Plan Assets 309.8 61.7 75.3 32.7 (433.6) (85.3) (103.3) (45.1) Benefits Paid - Pension (317.3) (66.1) (76.7) (35.7) (302.5) (63.3) (68.4) (33.9) Benefits Paid - Lump Sum (28.9) — (5.3) (1.0) (33.0) — (14.8) (1.0) Employee Transfers — 2.4 (0.5) — — (3.2) (5.7) 3.4 Fair Value of Pension Plan Assets as of End of Year $ 5,775.0 $ 1,170.0 $ 1,411.6 $ 614.0 $ 5,806.4 $ 1,172.0 $ 1,418.8 $ 618.0 Funded Status as of December 31st $ 536.6 $ 121.5 $ 304.6 $ 51.7 $ 586.3 $ 142.0 $ 308.4 $ 61.8 PBOP As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Change in Benefit Obligation: Benefit Obligation as of Beginning of Year $ (693.7) $ (127.9) $ (189.5) $ (74.6) $ (884.3) $ (165.5) $ (238.4) $ (92.3) Service Cost (7.6) (1.3) (1.2) (0.7) (11.6) (2.0) (2.0) (1.1) Interest Cost (33.8) (6.2) (9.2) (3.7) (20.2) (3.7) (5.3) (2.2) Actuarial Gain/(Loss) 5.0 4.4 (5.8) 0.8 173.6 33.0 39.4 15.2 Benefits Paid 52.7 10.0 16.7 6.1 52.1 10.4 16.6 6.0 Employee Transfers — — 0.5 (0.1) — (0.1) 0.2 (0.2) Plan Amendment 1.4 0.4 0.2 0.2 — — — — Impact of Acquisitions — — — — (3.3) — — — Benefit Obligation as of End of Year $ (676.0) $ (120.6) $ (188.3) $ (72.0) $ (693.7) $ (127.9) $ (189.5) $ (74.6) Change in Plan Assets: Fair Value of Plan Assets as of Beginning of Year $ 970.1 $ 120.6 $ 456.1 $ 72.3 $ 1,138.3 $ 145.7 $ 530.0 $ 88.0 Actual Return on Plan Assets 104.7 12.6 52.3 8.3 (119.6) (15.0) (57.0) (9.8) Employer Contributions 1.9 — — — 3.1 — — — Benefits Paid (52.3) (10.0) (16.7) (6.1) (51.7) (10.4) (16.6) (6.0) Employee Transfers — (0.2) (1.3) 0.2 — 0.3 (0.3) 0.1 Fair Value of Plan Assets as of End of Year $ 1,024.4 $ 123.0 $ 490.4 $ 74.7 $ 970.1 $ 120.6 $ 456.1 $ 72.3 Funded Status as of December 31st $ 348.4 $ 2.4 $ 302.1 $ 2.7 $ 276.4 $ (7.3) $ 266.6 $ (2.3)
Schedule of Defined Benefit Plans	As of December 31, 2023 and 2022, the accumulated benefit obligation for the Pension and SERP Plans is as follows: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2023 $ 4,936.8 $ 977.8 $ 1,051.9 $ 522.1 2022 4,911.6 960.7 1,055.1 516.9 A reconciliation of the prepaid assets and liabilities within the Eversource Pension, SERP and PBOP Plans’ funded status to the balance sheets is as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Prepaid Pension $ 672.2 $ 127.4 $ 306.5 $ 56.3 $ 756.7 $ 147.9 $ 310.2 $ 66.4 Prepaid PBOP 356.0 2.4 302.1 2.7 288.8 — 266.6 — Prepaid Pension and PBOP $ 1,028.2 $ 129.8 $ 608.6 $ 59.0 $ 1,045.5 $ 147.9 $ 576.8 $ 66.4 Accrued Pension $ — $ — $ — $ — $ 3.7 $ — $ — $ — Accrued SERP 135.6 5.9 1.9 4.6 166.7 5.9 1.8 4.6 Accrued PBOP 7.6 — — — 12.4 7.3 — 2.3 Less: Accrued SERP - current portion (19.4) (0.3) (0.2) (0.4) (47.3) (0.3) (0.2) (0.4) Accrued Pension, SERP and PBOP $ 123.8 $ 5.6 $ 1.7 $ 4.2 $ 135.5 $ 12.9 $ 1.6 $ 6.5
Schedule of Assumptions Used	The following actuarial assumptions were used in calculating the Pension, SERP and PBOP Plans' year end funded status: Pension and SERP PBOP As of December 31, As of December 31, 2023 2022 2023 2022 Discount Rate 4.9% — 5.0% 5.1% — 5.2% 5.0% — 5.2% 5.2% Compensation/Progression Rate 3.5% — 4.0% 3.5% — 4.0% N/A The following actuarial assumptions were used to calculate Pension, SERP and PBOP expense amounts: Pension and SERP PBOP For the Years Ended December 31, For the Years Ended December 31, 2023 2022 2021 2023 2022 2021 Discount Rate 4.9% — 5.3% 2.2% — 3.2% 1.5% — 3.0% 5.1% — 5.4% 2.3% — 3.3% 1.8% — 3.1% Expected Long-Term Rate of Return 8.25% 8.25% 8.25% 8.25% 8.25% 8.25% Compensation/Progression Rate 3.5% — 4.0% 3.5% — 4.0% 3.5% — 4.0% N/A N/A N/A
Schedule of Net Benefit Costs	The components of net periodic benefit plan expense/(income) for the Pension, SERP and PBOP Plans, prior to amounts capitalized as Property, Plant and Equipment or deferred as regulatory assets/(liabilities) for future recovery or refund, are shown below. The service cost component of net periodic benefit plan 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 plan 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 intercompany allocations of net periodic benefit plan expense/(income), as these amounts are cash settled on a short-term basis. Pension and SERP PBOP For the Year Ended December 31, 2023 For the Year Ended December 31, 2023 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 43.1 $ 12.3 $ 7.8 $ 4.3 $ 7.6 $ 1.3 $ 1.2 $ 0.7 Interest Cost 254.0 50.5 53.9 27.3 33.8 6.2 9.2 3.7 Expected Return on Plan Assets (465.0) (94.2) (113.8) (49.5) (77.1) (9.4) (36.9) (5.5) Actuarial Loss 45.8 2.5 17.1 1.5 — — — — Prior Service Cost/(Credit) 1.3 — 0.3 — (21.6) 1.1 (17.0) 0.4 Settlement Loss 12.4 — — — — — — — Total Net Periodic Benefit Plan Income $ (108.4) $ (28.9) $ (34.7) $ (16.4) $ (57.3) $ (0.8) $ (43.5) $ (0.7) Intercompany Income Allocations N/A $ (4.0) $ (3.0) $ (0.8) N/A $ (1.9) $ (2.1) $ (0.7) Pension and SERP PBOP For the Year Ended December 31, 2022 For the Year Ended December 31, 2022 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 70.1 $ 18.7 $ 13.8 $ 6.9 $ 11.6 $ 2.0 $ 2.0 $ 1.1 Interest Cost 154.5 31.3 32.8 16.9 20.2 3.7 5.3 2.2 Expected Return on Plan Assets (523.6) (106.3) (128.4) (56.1) (89.9) (11.4) (42.4) (6.7) Actuarial Loss 116.0 16.2 32.8 7.9 — — — — Prior Service Cost/(Credit) 1.4 — 0.3 — (21.7) 1.1 (17.0) 0.4 Total Net Periodic Benefit Plan Income $ (181.6) $ (40.1) $ (48.7) $ (24.4) $ (79.8) $ (4.6) $ (52.1) $ (3.0) Intercompany Income Allocations N/A $ (16.0) $ (12.4) $ (3.6) N/A $ (3.7) $ (3.6) $ (1.2) Pension and SERP PBOP For the Year Ended December 31, 2021 For the Year Ended December 31, 2021 (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Service Cost $ 85.8 $ 23.0 $ 15.8 $ 8.9 $ 13.5 $ 2.3 $ 2.4 $ 1.2 Interest Cost 130.0 27.3 26.8 14.5 17.4 3.2 4.4 1.8 Expected Return on Plan Assets (437.5) (86.8) (108.1) (47.5) (79.1) (10.3) (36.9) (6.1) Actuarial Loss 243.9 45.5 61.6 20.7 8.9 1.8 2.4 0.7 Prior Service Cost/(Credit) 1.4 — 0.3 — (21.2) 1.1 (17.0) 0.4 Total Net Periodic Benefit Plan Expense/(Income) $ 23.6 $ 9.0 $ (3.6) $ (3.4) $ (60.5) $ (1.9) $ (44.7) $ (2.0) Intercompany Expense/(Income) Allocations N/A $ 8.0 $ 8.8 $ 2.7 N/A $ (1.6) $ (1.9) $ (0.6)
Schedule of Amounts Recognized in Regulatory Assets and OCI	The following is a summary of the changes in plan assets and benefit obligations recognized in Regulatory Assets and Other Comprehensive Income (OCI) as well as amounts in Regulatory Assets and OCI that were reclassified as net periodic benefit expense during the years presented: Pension and SERP PBOP Regulatory Assets OCI Regulatory Assets OCI For the Years Ended December 31, For the Years Ended December 31, (Millions of Dollars) 2023 2022 2023 2022 2023 2022 2023 2022 Actuarial (Gain)/Loss Arising During the Year $ 251.1 $ (431.6) $ 14.0 $ 4.6 $ (32.0) $ 36.8 $ (0.3) $ (0.8) Actuarial Loss Reclassified as Net Periodic Benefit Expense (38.8) (107.0) (7.0) (9.0) — — — — Settlement Loss — — (12.4) — — — — — Prior Service Credit Arising During the Year — — — — (0.9) — — — Prior Service (Cost)/Credit Reclassified as Net Periodic (1.2) (1.2) (0.1) (0.2) 21.8 21.8 (0.2) (0.1) The following is a summary of the remaining Regulatory Assets and Accumulated Other Comprehensive Income amounts that have not been recognized as components of net periodic benefit expense as of December 31, 2023 and 2022: Regulatory Assets as of December 31, AOCI as of December 31, (Millions of Dollars) 2023 2022 2023 2022 Pension and SERP Actuarial Loss $ 1,101.0 $ 888.7 $ 56.5 $ 61.9 Prior Service Cost 2.9 4.1 0.3 0.4 PBOP Actuarial Loss $ 49.8 $ 81.8 $ 2.4 $ 2.7 Prior Service (Credit)/Cost (87.4) (108.3) 0.7 0.9
Schedule of Expected Benefit Payments	The following benefit payments, which reflect expected future service, are expected to be paid by the Pension, SERP and PBOP Plans: (Millions of Dollars) 2024 2025 2026 2027 2028 2029 - 2033 Pension and SERP $ 370.2 $ 367.1 $ 370.8 $ 373.8 $ 375.0 $ 1,864.3 PBOP 55.2 54.7 53.8 52.8 51.8 241.1
Schedule of Allocation of Plan Assets	These long-term rates of return are based on the assumed rates of return for the target asset allocations as follows: As of December 31, 2023 2022 Target Asset Allocation Assumed Rate of Return Target Asset Allocation Assumed Rate of Return Eversource Pension Plan Eversource PBOP Plan Eversource Pension Plan and PBOP Plan Eversource Pension Plan and PBOP Plan Equity Securities: United States — % 20.0 % 8.5 % 15.0 % 8.5 % Global 20.0 % — % 8.75 % 10.0 % 8.75 % Non-United States — % 11.0 % 8.5 % 8.0 % 8.5 % Emerging Markets — % 6.0 % 10.0 % 4.0 % 10.0 % Debt Securities: Fixed Income 16.0 % 17.0 % 5.5 % 13.0 % 4.0 % Public High Yield Fixed Income 5.0 % — % 7.5 % 4.0 % 6.5 % United States Treasuries 11.0 % — % 4.5 % — % — % Private Debt 10.0 % 13.0 % 10.0 % 13.0 % 9.0 % Private Equity 23.0 % 18.0 % 12.0 % 18.0 % 12.0 % Real Assets 15.0 % 15.0 % 7.5 % 15.0 % 7.5 % The following tables present, by asset category, the Pension and PBOP Plan assets recorded at fair value on a recurring basis by the level in which they are classified within the fair value hierarchy: Pension Plan Fair Value Measurements as of December 31, (Millions of Dollars) 2023 2022 Asset Category: Level 1 Level 2 Uncategorized Total Level 1 Level 2 Uncategorized Total Equity Securities $ 374.0 $ — $ 853.0 $ 1,227.0 $ 407.7 $ — $ 1,102.2 $ 1,509.9 Fixed Income (1) 354.6 340.9 1,516.4 2,211.9 277.1 78.5 1,598.8 1,954.4 Private Equity — — 1,685.3 1,685.3 — — 1,684.9 1,684.9 Real Assets 173.6 — 722.1 895.7 181.8 — 731.0 912.8 Total $ 902.2 $ 340.9 $ 4,776.8 $ 6,019.9 $ 866.6 $ 78.5 $ 5,116.9 $ 6,062.0 Less: 401(h) PBOP Assets (2) (244.9) (255.6) Total Pension Assets $ 5,775.0 $ 5,806.4 PBOP Plan Fair Value Measurements as of December 31, (Millions of Dollars) 2023 2022 Asset Category: Level 1 Level 2 Uncategorized Total Level 1 Level 2 Uncategorized Total Equity Securities $ 139.1 $ — $ 212.1 $ 351.2 $ 153.2 $ — $ 183.5 $ 336.7 Fixed Income 33.4 43.0 159.8 236.2 18.2 40.2 141.1 199.5 Private Equity — — 87.7 87.7 — — 70.9 70.9 Real Assets 70.5 — 33.9 104.4 71.2 — 36.2 107.4 Total $ 243.0 $ 43.0 $ 493.5 $ 779.5 $ 242.6 $ 40.2 $ 431.7 $ 714.5 Add: 401(h) PBOP Assets (2) 244.9 255.6 Total PBOP Assets $ 1,024.4 $ 970.1 (1) Fixed Income investments classified as Level 1 as of December 31, 2023 and 2022 include pending purchases and pending redemption settlements of $31 million and $138 million, respectively. (2) The assets of the Pension Plan include a 401(h) account that has been allocated to provide health and welfare postretirement benefits under the PBOP Plan.
Schedule of Defined Contribution Plans	The total Eversource 401k Plan employer matching contributions, including the K-Vantage contributions, were as follows: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH 2023 $ 67.3 $ 9.0 $ 13.7 $ 5.4 2022 59.9 7.7 12.8 4.8 2021 55.5 7.0 12.2 4.3
Summary of Share Transactions	A summary of RSU transactions is as follows: RSUs Weighted Average Outstanding as of December 31, 2022 629,734 $ 68.52 Granted 248,124 $ 76.42 Shares Issued (181,409) $ 87.09 Forfeited (24,207) $ 83.43 Outstanding as of December 31, 2023 672,242 $ 65.89 Performance Shares Weighted Average Outstanding as of December 31, 2022 547,290 $ 87.49 Granted 278,983 $ 83.39 Shares Issued (125,677) $ 90.49 Forfeited (36,172) $ 85.13 Outstanding as of December 31, 2023 664,424 $ 85.33
Schedule of Compensation Expense and Income Tax Benefit	The total compensation expense and associated future income tax benefits recognized by Eversource, CL&P, NSTAR Electric and PSNH for share-based compensation awards were as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Compensation Expense $ 27.8 $ 33.4 $ 28.2 Future Income Tax Benefit 7.3 8.7 7.3 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Compensation Expense $ 8.7 $ 8.7 $ 3.0 $ 10.0 $ 10.7 $ 3.6 $ 8.8 $ 9.0 $ 3.0 Future Income Tax Benefit 2.3 2.3 0.8 2.6 2.8 0.9 2.3 2.3 0.8
Schedule of Other Retirement Benefits	The liability and expense amounts are as follows: Eversource (Millions of Dollars) As of and For the Years Ended December 31, 2023 2022 2021 Actuarially-Determined Liability $ 32.6 $ 43.4 $ 42.8 Other Retirement Benefits Expense (1) 2.6 10.9 2.2 As of and For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Actuarially-Determined Liability $ 0.2 $ — $ 1.1 $ 0.2 $ 0.1 $ 1.3 $ 0.2 $ 0.1 $ 1.5 Other Retirement Benefits Expense (1) 0.8 0.8 0.4 4.0 3.7 1.3 0.7 0.7 0.3 (1) Other Retirement Benefits Expense in 2022 includes a one-time special retirement benefit payable of $9.2 million, which was paid in 2023.

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Components of Income Tax Expense	The components of income tax expense are as follows: Eversource (Millions of Dollars) For the Years Ended December 31, 2023 2022 2021 Current Income Taxes: Federal $ 75.8 $ 95.8 $ 21.5 State 0.6 13.6 (21.6) Total Current 76.4 109.4 (0.1) Deferred Income Taxes, Net: Federal (0.9) 198.8 199.7 State 86.3 148.0 147.4 Total Deferred 85.4 346.8 347.1 Investment Tax Credits, Net (2.1) (2.6) (2.8) Income Tax Expense $ 159.7 $ 453.6 $ 344.2 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Current Income Taxes: Federal $ (10.8) $ 50.7 $ (40.0) $ 106.2 $ 55.0 $ 29.6 $ 15.0 $ 52.3 $ 43.1 State (2.3) 7.8 (20.0) 20.1 8.7 5.9 (7.0) 6.2 10.8 Total Current (13.1) 58.5 (60.0) 126.3 63.7 35.5 8.0 58.5 53.9 Deferred Income Taxes, Net: Federal 130.3 50.1 81.2 17.2 35.6 5.9 76.3 16.3 (14.9) State 53.7 46.1 37.8 28.2 42.4 9.9 47.6 41.2 0.4 Total Deferred 184.0 96.2 119.0 45.4 78.0 15.8 123.9 57.5 (14.5) Investment Tax Credits, Net — (1.7) — (0.5) (1.7) — (0.6) (1.7) — Income Tax Expense $ 170.9 $ 153.0 $ 59.0 $ 171.2 $ 140.0 $ 51.3 $ 131.3 $ 114.3 $ 39.4
Summary of Reconciliation Between Income Tax Expense and Expected Tax	A reconciliation between income tax expense and the expected tax expense at the statutory rate is as follows: Eversource (Millions of Dollars, except percentages) For the Years Ended December 31, 2023 2022 2021 (Loss)/Income Before Income Tax Expense $ (275.0) $ 1,866.0 $ 1,572.3 Statutory Federal Income Tax Expense at 21% (57.7) 391.9 330.2 Tax Effect of Differences: Depreciation (25.8) (17.1) (18.1) Investment Tax Credit Amortization (2.1) (2.6) (2.8) State Income Taxes, Net of Federal Impact (11.4) 75.9 54.4 Dividends on ESOP (5.3) (5.1) (5.1) Tax Asset Valuation Allowance/Reserve Adjustments 295.8 51.6 44.6 Tax Deficiency/(Excess Stock Benefit) 0.5 (2.1) (4.0) EDIT Amortization (51.5) (49.1) (69.1) Other, Net 17.2 10.2 14.1 Income Tax Expense $ 159.7 $ 453.6 $ 344.2 Effective Tax Rate (58.1) % 24.3 % 21.9 % . For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars, except percentages) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Income Before Income Tax Expense $ 689.6 $ 697.5 $ 254.7 $ 704.1 $ 632.4 $ 222.9 $ 533.0 $ 590.9 $ 189.8 Statutory Federal Income Tax Expense at 21% 144.9 146.5 53.5 147.9 132.8 46.8 111.9 124.1 39.9 Tax Effect of Differences: Depreciation (5.6) (8.8) (1.0) (3.7) (4.2) 0.9 (6.4) (3.4) (0.2) Investment Tax Credit Amortization — (1.7) — (0.5) (1.7) — (0.6) (1.7) — State Income Taxes, Net of Federal Impact (10.7) 42.5 14.1 (6.6) 40.3 12.5 (4.6) 37.5 8.9 Tax Asset Valuation 51.3 — — 44.7 — — 36.7 — — Tax Deficiency/(Excess Stock Benefit) 0.2 0.2 0.1 (0.7) (0.8) (0.3) (1.5) (1.4) (0.5) EDIT Amortization (10.5) (28.4) (6.8) (9.2) (29.2) (7.7) (9.8) (43.2) (10.5) Other, Net 1.3 2.7 (0.9) (0.7) 2.8 (0.9) 5.6 2.4 1.8 Income Tax Expense $ 170.9 $ 153.0 $ 59.0 $ 171.2 $ 140.0 $ 51.3 $ 131.3 $ 114.3 $ 39.4 Effective Tax Rate 24.8 % 21.9 % 23.2 % 24.3 % 22.1 % 23.0 % 24.6 % 19.3 % 20.8 %
Schedule of Accumulated Deferred Income Tax Obligations	The tax effects of temporary differences that give rise to the net accumulated deferred income tax obligations are as follows: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Eversource CL&P NSTAR PSNH Deferred Tax Assets: Employee Benefits $ 244.5 $ 29.9 $ 66.8 $ 13.0 $ 228.9 $ 25.3 $ 57.4 $ 11.6 Derivative Liabilities 33.0 33.0 — — 53.8 53.8 — — Regulatory Deferrals - Liabilities 452.0 94.4 291.5 23.8 529.5 146.6 285.7 42.1 Allowance for Uncollectible Accounts 143.8 79.6 21.5 3.9 125.5 60.5 20.7 7.9 Tax Effect - Tax Regulatory Liabilities 739.0 320.7 227.1 95.5 762.9 324.6 241.8 97.8 Net Operating Loss Carryforwards 13.8 — — — 16.7 — — — Purchase Accounting Adjustment 56.7 — — — 62.0 — — — Equity Method Wind Investments 584.9 — — — — — — — Other 200.1 125.3 25.0 23.4 176.6 109.5 20.5 21.3 Total Deferred Tax Assets 2,467.8 682.9 631.9 159.6 1,955.9 720.3 626.1 180.7 Less: Valuation Allowance (1) 328.1 80.6 — — 82.8 63.3 — — Net Deferred Tax Assets $ 2,139.7 $ 602.3 $ 631.9 $ 159.6 $ 1,873.1 $ 657.0 $ 626.1 $ 180.7 Deferred Tax Liabilities: Accelerated Depreciation and Other $ 5,103.3 $ 1,703.4 $ 1,728.6 $ 566.5 $ 4,793.7 $ 1,602.0 $ 1,643.7 $ 523.8 Property Tax Accruals 95.0 42.0 39.8 6.3 95.3 40.7 41.3 6.7 Regulatory Amounts: Regulatory Deferrals - Assets 1,512.3 470.0 474.5 250.3 1,251.9 406.4 407.9 165.2 Tax Effect - Tax Regulatory Assets 284.0 191.9 10.5 8.3 271.7 185.6 10.7 7.9 Goodwill-related Regulatory Asset - 1999 Merger 72.2 — 61.9 — 76.8 — 65.9 — Employee Benefits 282.0 38.8 146.7 16.8 305.5 45.0 140.8 18.7 Derivative Assets 6.4 6.4 — — 10.5 10.5 — — Other 88.2 9.9 19.5 2.9 135.6 6.8 16.7 21.2 Total Deferred Tax Liabilities $ 7,443.4 $ 2,462.4 $ 2,481.5 $ 851.1 $ 6,941.0 $ 2,297.0 $ 2,327.0 $ 743.5 (1) As of December 31, 2023, the Eversource Valuation Allowance of $328.1 million includes $224.0 million related to the impairment of Eversource’s offshore wind investments.
Summary of Tax Credits and Loss Carryforwards	The following table provides the amounts and expiration dates of state tax credit and loss carryforwards and federal tax credit and net operating loss carryforwards: As of December 31, 2023 2022 (Millions of Dollars) Eversource CL&P NSTAR PSNH Expiration Range Eversource CL&P NSTAR PSNH Expiration Range State Net Operating Loss $ 243.4 $ — $ — $ — 2023 - 2041 $ 288.1 $ — $ — $ — 2022 - 2041 State Tax Credit 228.5 157.5 — — 2023 - 2028 204.5 137.7 — — 2022 - 2027 State Charitable Contribution 7.9 — — — 2023 - 2027 20.1 — — — 2022 - 2026
Summary of Income Tax Contingencies	A reconciliation of the activity in unrecognized tax benefits, all of which would impact the effective tax rate if recognized, is as follows: (Millions of Dollars) Eversource CL&P Balance as of January 1, 2021 $ 61.8 $ 25.8 Gross Increases - Current Year 11.3 3.8 Gross Decreases - Prior Year (0.3) (0.6) Lapse of Statute of Limitations (7.0) (2.8) Balance as of December 31, 2021 65.8 26.2 Gross Increases - Current Year 11.5 3.5 Gross Decreases - Prior Year (2.4) (0.9) Lapse of Statute of Limitations (7.8) (3.3) Balance as of December 31, 2022 67.1 25.5 Gross Increases - Current Year 23.4 4.0 Gross Increases - Prior Year 0.1 0.1 Gross Decreases - Prior Year (0.1) — Lapse of Statute of Limitations (9.2) (3.8) Balance as of December 31, 2023 $ 81.3 $ 25.8
Summary of Income Tax Examinations	The following table summarizes Eversource, CL&P, NSTAR Electric, and PSNH's tax years that remain subject to examination by major tax jurisdictions as of December 31, 2023: Description Tax Years Federal 2023 Connecticut 2020 - 2023 Massachusetts 2020 - 2023 New Hampshire 2020 - 2023

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Environmental Loss Contingencies by Site	A reconciliation of the activity in the environmental reserves is as follows: (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Balance as of January 1, 2022 $ 115.4 $ 13.9 $ 3.3 $ 6.3 Additions 12.6 0.9 0.4 0.5 Payments/Reductions (5.4) (0.9) (0.3) (0.7) Balance as of December 31, 2022 122.6 13.9 3.4 6.1 Additions 16.8 2.6 2.5 1.7 Payments/Reductions (11.2) (2.7) (0.5) (0.2) Balance as of December 31, 2023 $ 128.2 $ 13.8 $ 5.4 $ 7.6 The number of environmental sites for which remediation or long-term monitoring, preliminary site work or site assessment is being performed are as follows: Eversource CL&P NSTAR Electric PSNH 2023 65 16 12 8 2022 59 13 10 8
Schedule of Estimated Future Annual Costs of Long term Contractual Agreement	The estimated future annual costs of significant executed, non-cancelable, long-term contractual arrangements in effect as of December 31, 2023 are as follows: Eversource (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 769.4 $ 863.0 $ 867.9 $ 897.6 $ 893.1 $ 5,368.8 $ 9,659.8 Natural Gas Procurement 423.2 402.3 317.8 264.8 236.0 1,211.8 2,855.9 Purchased Power and Capacity 86.7 75.2 2.9 2.7 2.7 4.5 174.7 Peaker CfDs 17.2 14.1 12.8 9.1 6.8 43.7 103.7 Transmission Support Commitments 19.3 22.2 27.4 31.1 31.1 31.1 162.2 Total $ 1,315.8 $ 1,376.8 $ 1,228.8 $ 1,205.3 $ 1,169.7 $ 6,659.9 $ 12,956.3 CL&P (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 618.8 $ 628.3 $ 628.0 $ 631.2 $ 632.2 $ 2,087.8 $ 5,226.3 Purchased Power and Capacity 83.8 72.4 0.1 — — — 156.3 Peaker CfDs 17.2 14.1 12.8 9.1 6.8 43.7 103.7 Transmission Support Commitments 7.6 8.8 10.8 12.3 12.3 12.3 64.1 Total $ 727.4 $ 723.6 $ 651.7 $ 652.6 $ 651.3 $ 2,143.8 $ 5,550.4 NSTAR Electric (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 123.0 $ 202.9 $ 206.5 $ 209.3 $ 205.1 $ 2,983.5 $ 3,930.3 Purchased Power and Capacity 2.9 2.8 2.8 2.7 2.7 4.5 18.4 Transmission Support Commitments 7.6 8.7 10.8 12.3 12.3 12.3 64.0 Total $ 133.5 $ 214.4 $ 220.1 $ 224.3 $ 220.1 $ 3,000.3 $ 4,012.7 PSNH (Millions of Dollars) 2024 2025 2026 2027 2028 Thereafter Total Renewable Energy Purchase Contracts $ 27.6 $ 31.8 $ 33.4 $ 57.1 $ 55.8 $ 297.5 $ 503.2 Transmission Support Commitments 4.1 4.7 5.8 6.5 6.5 6.5 34.1 Total $ 31.7 $ 36.5 $ 39.2 $ 63.6 $ 62.3 $ 304.0 $ 537.3 The total costs incurred under these agreements were as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Renewable Energy Purchase Contracts $ 581.4 $ 678.1 $ 609.2 Natural Gas Procurement 695.8 1,042.8 712.7 Purchased Power and Capacity 69.0 61.6 56.4 Peaker CfDs 20.1 13.4 24.3 Transmission Support Commitments 14.2 12.7 15.4 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Renewable Energy Purchase Contracts $ 474.1 $ 60.0 $ 47.3 $ 513.2 $ 90.8 $ 74.1 $ 457.1 $ 84.7 $ 67.4 Purchased Power and Capacity 65.5 2.9 0.6 57.7 3.0 0.9 53.1 3.0 0.3 Peaker CfDs 20.1 — — 13.4 — — 24.3 — — Transmission Support Commitments 5.6 5.6 3.0 5.0 5.0 2.7 6.1 6.0 3.3
Schedule of Guarantor Obligations	The following table summarizes Eversource parent's exposure to guarantees and indemnifications of its subsidiaries and affiliates to external parties, and primarily relates to its offshore wind business: As of December 31, 2023 Company (Obligor) Description Maximum Exposure North East Offshore, LLC, Sunrise Wind LLC, Revolution Wind, LLC and South Fork Wind, LLC Offshore wind construction-related purchase agreements with third-party contractors (1) $ 1,941.1 Eversource Investment LLC and South Fork Class B Member, LLC Funding and indemnification obligations of South Fork Wind and North East Offshore, LLC (2) 485.9 Sunrise Wind LLC OREC capacity production (3) 11.0 South Fork Wind, LLC Power Purchase Agreement Security (4) 7.1 Eversource Investment LLC Letters of Credit (5) 15.2 Eversource TEI LLC South Fork Wind Tax Equity (6) — Various Surety bonds (7) 38.8 Sunrise Wind LLC Surety bonds (8) 20.5 (1) Eversource parent issued guarantees on behalf of its 50 percent-owned affiliates, North East Offshore, LLC (NEO), Sunrise Wind LLC, Revolution Wind, LLC and South Fork Wind, LLC, under which Eversource parent agreed to guarantee each entity’s performance of obligations under certain construction-related purchase agreements with third-party contractors, in an aggregate amount not to exceed $3.03 billion. Eversource parent’s obligations under the guarantees expire upon the earlier of (i) dates ranging between May 2024 and October 2028 and (ii) full performance of the guaranteed obligations. Eversource parent also issued a separate guarantee to Ørsted on behalf of NEO, under which Eversource parent agreed to guarantee 50 percent of NEO’s payment obligations under certain offshore wind project construction-related agreements with Ørsted in an aggregate amount not to exceed $62.5 million and expiring upon full performance of the guaranteed obligation. (2) Eversource parent issued guarantees on behalf of its wholly-owned subsidiary Eversource Investment LLC (EI), which holds Eversource's investments in offshore wind-related equity method investments, and on behalf of its 50 percent-owned affiliate, South Fork Class B Member, LLC, whereby Eversource parent will guarantee each entity’s performance of certain capital expenditure funding obligations during the construction phases of the South Fork Wind project and NEO’s underlying offshore wind projects. Eversource parent also guaranteed certain indemnification obligations of EI associated with third party credit support for EI’s investment in NEO. These guarantees will not exceed $1.52 billion and expire upon the full performance of the guaranteed obligations. (3) Eversource parent issued a guarantee on behalf of its 50 percent-owned affiliate, Sunrise Wind LLC, whereby Eversource parent will guarantee 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 by and between the New York State Energy Research and Development Authority (NYSERDA) and Sunrise Wind LLC. The guarantee expires upon the full performance of the guaranteed obligations. Effective January 1, 2024, the maximum exposure under the guarantee increased from $11.0 million to $15.4 million. (4) Eversource parent issued a guarantee on behalf of its 50 percent-owned affiliate, South Fork Wind, LLC, whereby Eversource parent will guarantee South Fork Wind, LLC's performance of certain obligations, in an amount not to exceed $7.1 million, under a Power Purchase Agreement between the Long Island Power Authority and South Fork Wind, LLC (the Agreement). The guarantee expires upon the later of (i) the end of the Agreement term and (ii) full performance of the guaranteed obligations. (5) Eversource parent entered into a guarantee on behalf of EI, under which Eversource parent would guarantee EI's obligations under a letter of credit facility with a financial institution that EI may request in an aggregate amount of up to approximately $25 million. As of December 31, 2023, EI has issued letters of credit on behalf of South Fork Wind, LLC, Sunrise Wind LLC and Revolution Wind, LLC totaling $15.2 million. In January 2024, EI issued two additional letters of credit on behalf of Sunrise Wind LLC totaling $8.0 million. The guarantee will remain in effect until full performance of the guaranteed obligations. (6) Eversource parent issued a guarantee on behalf of its wholly-owned subsidiary, Eversource TEI LLC, whereby Eversource parent will guarantee Eversource TEI LLC’s performance of certain obligations, in an amount not to exceed $528.4 million, primarily in connection with tax equity funding obligations during the construction phase of the South Fork Wind project. Eversource parent’s obligations expire upon the full performance of the guaranteed obligations. (7) Surety bonds expire in 2024. 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. (8)

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Components of Lease Cost	The components of lease cost, prior to amounts capitalized, are as follows: Eversource For the Years Ended December 31, (Millions of Dollars) 2023 2022 2021 Finance Lease Cost: Amortization of Right-of-use-Assets $ 4.8 $ 8.3 $ 4.6 Interest on Lease Liabilities 2.0 2.0 3.9 Total Finance Lease Cost 6.8 10.3 8.5 Operating Lease Cost 11.4 11.6 12.2 Variable Lease Cost 69.2 78.1 61.0 Total Lease Cost $ 87.4 $ 100.0 $ 81.7 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR PSNH CL&P NSTAR PSNH CL&P NSTAR PSNH Finance Lease Cost: Amortization of Right-of-use-Assets $ — $ 0.2 $ — $ — $ 0.2 $ 0.1 $ 0.5 $ 0.2 $ 0.1 Interest on Lease Liabilities — 0.6 — — 0.6 — 0.1 0.6 — Total Finance Lease Cost — 0.8 — — 0.8 0.1 0.6 0.8 0.1 Operating Lease Cost 0.7 3.0 0.4 0.3 2.3 0.1 0.3 2.3 0.1 Variable Lease Cost 21.9 — 47.3 25.6 — 52.5 16.2 — 44.8 Total Lease Cost $ 22.6 $ 3.8 $ 47.7 $ 25.9 $ 3.1 $ 52.7 $ 17.1 $ 3.1 $ 45.0
Supplemental Balance Sheet Information Related to Leases	Supplemental balance sheet information related to leases is as follows: As of December 31, 2023 As of December 31, 2022 (Millions of Dollars) Balance Sheet Classification Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Operating Leases: Right-of-use-Assets, Net Other Long-Term Assets $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 56.9 $ 2.2 $ 22.5 $ — Operating Lease Liabilities Current Portion Other Current Liabilities $ 9.5 $ 0.8 $ 2.2 $ 1.5 $ 9.0 $ 0.6 $ 1.2 $ — Long-Term Other Long-Term Liabilities 44.0 1.4 25.5 3.2 47.9 1.6 21.3 — Total Operating Lease Liabilities $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 56.9 $ 2.2 $ 22.5 $ — Finance Leases: Right-of-use-Assets, Net Property, Plant and Equipment, Net $ 68.6 $ 18.3 $ 3.0 $ — $ 54.5 $ — $ 3.2 $ — Finance Lease Liabilities Current Portion Other Current Liabilities $ 5.4 $ 1.4 $ — $ — $ 3.8 $ — $ — $ — Long-Term Other Long-Term Liabilities 67.3 16.9 4.9 — 54.2 — 4.9 — Total Finance Lease Liabilities $ 72.7 $ 18.3 $ 4.9 $ — $ 58.0 $ — $ 4.9 $ —
Other Information Related to Leases	Other information related to leases is as follows: As of December 31, 2023 2022 Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric PSNH Weighted-Average Remaining Lease Term (Years): Operating Leases 9 4 13 3 11 4 17 — Finance Leases 13 9 18 — 15 — 19 — Weighted-Average Discount Rate (Percentage): Operating Leases 4.0 % 5.2 % 4.2 % 5.2 % 3.2 % 3.8 % 4.0 % — % Finance Leases 3.3 % 5.3 % 2.9 % — % 2.7 % — % 2.9 % — % (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2023 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 10.5 $ 0.7 $ 2.5 $ 0.4 Operating Cash Flows from Finance Leases 2.0 — 0.6 — Financing Cash Flows from Finance Leases 3.9 — — — Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 12.8 0.6 7.0 5.0 Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 18.5 18.3 — — (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2022 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 11.3 $ 0.3 $ 2.1 $ 0.1 Operating Cash Flows from Finance Leases 2.0 — 0.6 — Financing Cash Flows from Finance Leases 3.9 — — 0.1 Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 18.9 2.4 — — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 3.5 — — — (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH For the Year Ended December 31, 2021 Cash Paid for Amounts Included in the Measurement of Lease Liabilities: Operating Cash Flows from Operating Leases $ 12.1 $ 0.3 $ 2.1 $ 0.1 Operating Cash Flows from Finance Leases 3.4 0.1 0.6 — Financing Cash Flows from Finance Leases 4.1 1.4 — 0.1 Supplemental Non-Cash Information on Lease Liabilities: Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities 2.1 — 1.9 — Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities 2.3 — — —
Future Minimum Lease Payments under Long-Term Finance Leases	Future minimum lease payments, excluding variable costs, under long-term leases, as of December 31, 2023 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric Year Ending December 31, 2024 $ 11.1 $ 0.9 $ 3.4 $ 1.7 $ 7.8 $ 1.9 $ 0.6 2025 8.3 0.9 3.0 1.7 8.2 2.3 0.7 2026 6.9 0.5 3.0 1.5 7.8 2.4 0.7 2027 4.3 — 2.3 0.1 7.9 2.5 0.7 2028 4.3 — 2.4 — 7.2 2.6 0.7 Thereafter 30.3 — 24.6 — 57.8 11.5 11.0 Future lease payments 65.2 2.3 38.7 5.0 96.7 23.2 14.4 Less amount representing interest 11.7 0.1 11.0 0.3 24.0 4.9 9.5 Present value of future minimum lease payments $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 72.7 $ 18.3 $ 4.9
Future Minimum Lease Payments under Long-Term Operating Leases	Future minimum lease payments, excluding variable costs, under long-term leases, as of December 31, 2023 are as follows: Operating Leases Finance Leases (Millions of Dollars) Eversource CL&P NSTAR Electric PSNH Eversource CL&P NSTAR Electric Year Ending December 31, 2024 $ 11.1 $ 0.9 $ 3.4 $ 1.7 $ 7.8 $ 1.9 $ 0.6 2025 8.3 0.9 3.0 1.7 8.2 2.3 0.7 2026 6.9 0.5 3.0 1.5 7.8 2.4 0.7 2027 4.3 — 2.3 0.1 7.9 2.5 0.7 2028 4.3 — 2.4 — 7.2 2.6 0.7 Thereafter 30.3 — 24.6 — 57.8 11.5 11.0 Future lease payments 65.2 2.3 38.7 5.0 96.7 23.2 14.4 Less amount representing interest 11.7 0.1 11.0 0.3 24.0 4.9 9.5 Present value of future minimum lease payments $ 53.5 $ 2.2 $ 27.7 $ 4.7 $ 72.7 $ 18.3 $ 4.9

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Carrying Amounts and Estimated Fair Values of Financial Instruments	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 Fair Carrying Fair Carrying Fair As of December 31, 2023: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 122.2 $ 116.2 $ 90.4 $ 43.0 $ 31.8 $ — $ — Long-Term Debt 24,413.5 22,855.2 4,814.4 4,572.0 4,496.9 4,273.7 1,431.6 1,292.6 Rate Reduction Bonds 410.5 395.0 — — — — 410.5 395.0 As of December 31, 2022: Preferred Stock Not Subject to Mandatory Redemption $ 155.6 $ 136.7 $ 116.2 $ 99.2 $ 43.0 $ 37.5 $ — $ — Long-Term Debt 21,044.1 18,891.3 4,216.5 3,828.3 4,425.1 4,091.8 1,164.6 970.5 Rate Reduction Bonds 453.7 424.7 — — — — 453.7 424.7

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Tables)	12 Months Ended
	Dec. 31, 2023
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 Year Ended December 31, 2023 For the Year Ended December 31, 2022 Eversource (Millions of Dollars) Qualified Unrealized Defined Total Qualified Unrealized Defined Total Balance as of January 1st $ (0.4) $ (1.2) $ (37.8) $ (39.4) $ (0.4) $ 0.4 $ (42.3) $ (42.3) OCI Before Reclassifications — — (8.8) (8.8) — (1.6) (2.5) (4.1) Amounts Reclassified from AOCI — 1.2 13.3 14.5 — — 7.0 7.0 Net OCI — 1.2 4.5 5.7 — (1.6) 4.5 2.9 Balance as of December 31st $ (0.4) $ — $ (33.3) $ (33.7) $ (0.4) $ (1.2) $ (37.8) $ (39.4)
Schedule of Amounts Reclassified from AOCI by Component	The following table sets forth the amounts reclassified from AOCI by component and the impacted line item on the statements of income: Amounts Reclassified from AOCI Eversource (Millions of Dollars) For the Years Ended December 31, Statements of Income 2023 2022 2021 Qualified Cash Flow Hedging Instruments $ — $ — $ (1.7) Interest Expense Tax Effect — — 0.7 Income Tax Expense Qualified Cash Flow Hedging Instruments, Net of Tax — — (1.0) Unrealized Gains/(Losses) on Marketable Securities (1.6) — — Other Income, Net Tax Effect 0.4 — — Income Tax Expense Unrealized Gains/(Losses) on Marketable Securities, Net of Tax (1.2) — — Defined Benefit Plan Costs: Amortization of Actuarial Losses (7.0) (9.0) (13.1) Other Income, Net (1) Amortization of Prior Service Cost (0.3) (0.3) — Other Income, Net (1) Settlement Loss (12.4) — — Other Income, Net (1) Total Defined Benefit Plan Costs (19.7) (9.3) (13.1) Tax Effect 6.4 2.3 3.4 Income Tax Expense Defined Benefit Plan Costs, Net of Tax (13.3) (7.0) (9.7) Total Amounts Reclassified from AOCI, Net of Tax $ (14.5) $ (7.0) $ (10.7) (1) These amounts are included in the computation of net periodic Pension, SERP and PBOP costs. See Note 1K, "Summary of Significant Accounting Policies – Other Income, Net" and Note 11A, "Employee Benefits – Pension Benefits and Postretirement Benefits Other Than Pension," for further information.

COMMON SHARES (Tables)

COMMON SHARES (Tables)	12 Months Ended
	Dec. 31, 2023
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 Par Value Authorized as of December 31, Issued as of December 31, 2023 2022 2023 2022 Eversource $ 5 410,000,000 380,000,000 359,984,073 359,984,073 CL&P $ 10 24,500,000 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 100,000,000 200 200 PSNH $ 1 100,000,000 100,000,000 301 301 Details of preferred stock not subject to mandatory redemption are as follows (in millions, except in redemption price and shares): Redemption Price Shares Outstanding as of December 31, As of December 31, Series 2023 2022 2023 2022 CL&P $1.90 Series of 1947 $ 52.50 163,912 163,912 $ 8.2 $ 8.2 $2.00 Series of 1947 $ 54.00 336,088 336,088 16.8 16.8 $2.04 Series of 1949 $ 52.00 100,000 100,000 5.0 5.0 $2.20 Series of 1949 $ 52.50 200,000 200,000 10.0 10.0 3.90% Series of 1949 $ 50.50 160,000 160,000 8.0 8.0 $2.06 Series E of 1954 $ 51.00 200,000 200,000 10.0 10.0 $2.09 Series F of 1955 $ 51.00 100,000 100,000 5.0 5.0 4.50% Series of 1956 $ 50.75 104,000 104,000 5.2 5.2 4.96% Series of 1958 $ 50.50 100,000 100,000 5.0 5.0 4.50% Series of 1963 $ 50.50 160,000 160,000 8.0 8.0 5.28% Series of 1967 $ 51.43 200,000 200,000 10.0 10.0 $3.24 Series G of 1968 $ 51.84 300,000 300,000 15.0 15.0 6.56% Series of 1968 $ 51.44 200,000 200,000 10.0 10.0 Total CL&P 2,324,000 2,324,000 $ 116.2 $ 116.2 NSTAR Electric 4.25% Series of 1956 $ 103.625 180,000 180,000 $ 18.0 $ 18.0 4.78% Series of 1958 $ 102.80 250,000 250,000 25.0 25.0 Total NSTAR Electric 430,000 430,000 $ 43.0 $ 43.0 Fair Value Adjustment due to Merger with NSTAR (3.6) (3.6) Other 6.00% Series of 1958 $ 100.00 13 23 $ — $ — Total Eversource - Noncontrolling Interest - Preferred Stock of Subsidiaries $ 155.6 $ 155.6

PREFERRED STOCK NOT SUBJECT T_2

PREFERRED STOCK NOT SUBJECT TO MANDATORY REDEMPTION (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Preferred Stock Not Subject to Mandatory Redemption	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 Par Value Authorized as of December 31, Issued as of December 31, 2023 2022 2023 2022 Eversource $ 5 410,000,000 380,000,000 359,984,073 359,984,073 CL&P $ 10 24,500,000 24,500,000 6,035,205 6,035,205 NSTAR Electric $ 1 100,000,000 100,000,000 200 200 PSNH $ 1 100,000,000 100,000,000 301 301 Details of preferred stock not subject to mandatory redemption are as follows (in millions, except in redemption price and shares): Redemption Price Shares Outstanding as of December 31, As of December 31, Series 2023 2022 2023 2022 CL&P $1.90 Series of 1947 $ 52.50 163,912 163,912 $ 8.2 $ 8.2 $2.00 Series of 1947 $ 54.00 336,088 336,088 16.8 16.8 $2.04 Series of 1949 $ 52.00 100,000 100,000 5.0 5.0 $2.20 Series of 1949 $ 52.50 200,000 200,000 10.0 10.0 3.90% Series of 1949 $ 50.50 160,000 160,000 8.0 8.0 $2.06 Series E of 1954 $ 51.00 200,000 200,000 10.0 10.0 $2.09 Series F of 1955 $ 51.00 100,000 100,000 5.0 5.0 4.50% Series of 1956 $ 50.75 104,000 104,000 5.2 5.2 4.96% Series of 1958 $ 50.50 100,000 100,000 5.0 5.0 4.50% Series of 1963 $ 50.50 160,000 160,000 8.0 8.0 5.28% Series of 1967 $ 51.43 200,000 200,000 10.0 10.0 $3.24 Series G of 1968 $ 51.84 300,000 300,000 15.0 15.0 6.56% Series of 1968 $ 51.44 200,000 200,000 10.0 10.0 Total CL&P 2,324,000 2,324,000 $ 116.2 $ 116.2 NSTAR Electric 4.25% Series of 1956 $ 103.625 180,000 180,000 $ 18.0 $ 18.0 4.78% Series of 1958 $ 102.80 250,000 250,000 25.0 25.0 Total NSTAR Electric 430,000 430,000 $ 43.0 $ 43.0 Fair Value Adjustment due to Merger with NSTAR (3.6) (3.6) Other 6.00% Series of 1958 $ 100.00 13 23 $ — $ — Total Eversource - Noncontrolling Interest - Preferred Stock of Subsidiaries $ 155.6 $ 155.6

EARNINGS_(LOSS) PER SHARE (Tabl

EARNINGS/(LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Components of Basic and Diluted EPS	The following table sets forth the components of basic and diluted earnings/(loss) per share: Eversource (Millions of Dollars, except share information) For the Years Ended December 31, 2023 2022 2021 Net (Loss)/Income Attributable to Common Shareholders $ (442.2) $ 1,404.9 $ 1,220.5 Weighted Average Common Shares Outstanding: Basic 349,580,638 346,783,444 343,972,926 Dilutive Effect 259,843 463,324 658,130 Diluted 349,840,481 347,246,768 344,631,056 Basic (Loss)/Earnings Per Common Share $ (1.27) $ 4.05 $ 3.55 Diluted (Loss)/Earnings Per Common Share $ (1.26) $ 4.05 $ 3.54

REVENUES (Tables)

REVENUES (Tables)	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	The following tables present operating revenues disaggregated by revenue source: For the Year Ended December 31, 2023 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 5,054.2 $ 1,145.4 $ — $ 144.7 $ — $ — $ 6,344.3 Commercial 2,893.2 637.7 — 69.8 — (4.8) 3,595.9 Industrial 352.4 186.8 — 4.5 — (19.7) 524.0 Total Retail Tariff Sales Revenues 8,299.8 1,969.9 — 219.0 — (24.5) 10,464.2 Wholesale Transmission Revenues — — 1,777.5 — — (1,310.5) 467.0 Wholesale Market Sales Revenues 625.0 206.7 — 3.9 — — 835.6 Other Revenues from Contracts with Customers 82.6 5.6 14.6 8.1 1,636.6 (1,628.0) 119.5 Amortization of Revenues Subject to Refund — — 4.3 — — — 4.3 Total Revenues from Contracts with Customers 9,007.4 2,182.2 1,796.4 231.0 1,636.6 (2,963.0) 11,890.6 Alternative Revenue Programs (54.3) 35.5 118.9 0.4 — (106.5) (6.0) Other Revenues 20.4 4.0 0.6 1.1 — — 26.1 Total Operating Revenues $ 8,973.5 $ 2,221.7 $ 1,915.9 $ 232.5 $ 1,636.6 $ (3,069.5) $ 11,910.7 For the Year Ended December 31, 2022 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 4,796.1 $ 1,204.9 $ — $ 141.7 $ — $ — $ 6,142.7 Commercial 2,903.3 648.5 — 66.5 — (4.1) 3,614.2 Industrial 374.9 199.7 — 4.7 — (20.1) 559.2 Total Retail Tariff Sales Revenues 8,074.3 2,053.1 — 212.9 — (24.2) 10,316.1 Wholesale Transmission Revenues — — 1,700.5 — — (1,264.5) 436.0 Wholesale Market Sales Revenues 1,190.9 140.8 — 3.8 — — 1,335.5 Other Revenues from Contracts with Customers 72.3 5.6 14.1 8.4 1,435.5 (1,425.3) 110.6 Amortization of/(Reserve for) Revenues 72.0 — 0.7 (0.7) — — 72.0 Total Revenues from Contracts with Customers 9,409.5 2,199.5 1,715.3 224.4 1,435.5 (2,714.0) 12,270.2 Alternative Revenue Programs (15.4) 14.8 92.7 (2.5) — (84.3) 5.3 Other Revenues 11.2 1.3 0.7 0.6 — — 13.8 Total Operating Revenues $ 9,405.3 $ 2,215.6 $ 1,808.7 $ 222.5 $ 1,435.5 $ (2,798.3) $ 12,289.3 For the Year Ended December 31, 2021 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Revenues from Contracts with Customers Retail Tariff Sales Residential $ 3,989.8 $ 1,000.3 $ — $ 133.5 $ — $ — $ 5,123.6 Commercial 2,486.1 497.6 — 62.8 — (5.1) 3,041.4 Industrial 345.3 167.2 — 4.3 — (17.1) 499.7 Total Retail Tariff Sales Revenues 6,821.2 1,665.1 — 200.6 — (22.2) 8,664.7 Wholesale Transmission Revenues — — 1,751.3 — 86.6 (1,384.7) 453.2 Wholesale Market Sales Revenues 575.8 82.1 — 3.9 — — 661.8 Other Revenues from Contracts with Customers 78.1 5.1 13.6 7.5 1,267.4 (1,257.7) 114.0 Reserve for Revenues Subject to Refund (71.1) — (5.0) (2.6) — — (78.7) Total Revenues from Contracts with Customers 7,404.0 1,752.3 1,759.9 209.4 1,354.0 (2,664.6) 9,815.0 Alternative Revenue Programs 14.7 37.0 (126.1) 1.5 — 114.6 41.7 Other Revenues 4.9 0.3 0.8 0.4 — — 6.4 Total Operating Revenues $ 7,423.6 $ 1,789.6 $ 1,634.6 $ 211.3 $ 1,354.0 $ (2,550.0) $ 9,863.1 For the Years Ended December 31, 2023 2022 2021 (Millions of Dollars) CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH CL&P NSTAR Electric PSNH Revenues from Contracts with Customers Retail Tariff Sales Residential $ 2,597.8 $ 1,691.0 $ 765.4 $ 2,397.2 $ 1,601.8 $ 797.1 $ 1,994.2 $ 1,375.8 $ 619.8 Commercial 1,082.1 1,442.3 369.6 1,067.9 1,457.4 380.8 890.6 1,265.0 332.2 Industrial 137.2 123.2 92.0 146.4 135.8 92.7 131.4 119.1 94.8 Total Retail Tariff Sales Revenues 3,817.1 3,256.5 1,227.0 3,611.5 3,195.0 1,270.6 3,016.2 2,759.9 1,046.8 Wholesale Transmission Revenues 794.7 692.0 290.8 755.1 670.4 275.0 863.3 616.3 271.7 Wholesale Market Sales Revenues 429.1 131.8 64.1 873.7 215.0 102.2 408.8 109.2 57.8 Other Revenues from Contracts 32.4 49.1 18.1 30.2 46.9 11.8 26.7 56.2 11.3 Amortization of/(Reserve for) Revenues 4.3 — — 72.7 — — (76.1) — — Total Revenues from Contracts 5,077.6 4,129.4 1,600.0 5,343.2 4,127.3 1,659.6 4,238.9 3,541.6 1,387.6 Alternative Revenue Programs 66.8 (52.0) 49.8 56.5 0.7 20.1 (78.9) (15.1) (17.4) Other Revenues 9.6 8.4 3.0 1.8 7.2 2.9 0.4 3.4 1.9 Eliminations (575.2) (570.3) (204.9) (583.8) (552.1) (207.8) (523.0) (473.5) (194.9) Total Operating Revenues $ 4,578.8 $ 3,515.5 $ 1,447.9 $ 4,817.7 $ 3,583.1 $ 1,474.8 $ 3,637.4 $ 3,056.4 $ 1,177.2

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Summary of Segment Information and Segmented Total Assets	Eversource's segment information is as follows: For the Year Ended December 31, 2023 Eversource (Millions of Dollars) Electric Natural Gas Electric Transmission Water Distribution Other Eliminations Total Operating Revenues $ 8,973.5 $ 2,221.7 $ 1,915.9 $ 232.5 $ 1,636.6 $ (3,069.5) $ 11,910.7 Depreciation and Amortization (18.2) (214.2) (371.2) (56.0) (158.8) 2.7 (815.7) Other Operating Expenses (8,104.6) (1,662.6) (550.5) (117.1) (1,329.8) 3,068.9 (8,695.7) Operating Income 850.7 344.9 994.2 59.4 148.0 2.1 2,399.3 Interest Expense (291.7) (85.7) (163.7) (38.5) (425.3) 149.5 (855.4) Impairments of Offshore Wind Investments — — — — (2,167.0) — (2,167.0) Interest Income 74.5 18.2 0.4 — 150.6 (149.5) 94.2 Other Income/(Loss), Net 136.2 20.4 41.2 5.9 (261.8) 312.0 253.9 Income Tax (Expense)/Benefit (157.1) (73.0) (225.8) 6.3 289.9 — (159.7) Net Income/(Loss) 612.6 224.8 646.3 33.1 (2,265.6) 314.1 (434.7) Net Income Attributable to Noncontrolling Interests (4.6) — (2.9) — — — (7.5) Net Income/(Loss) Attributable to $ 608.0 $ 224.8 $ 643.4 $ 33.1 $ (2,265.6) $ 314.1 $ (442.2) Total Assets (as of) $ 29,426.4 $ 8,775.3 $ 14,806.5 $ 2,944.8 $ 26,337.7 $ (26,678.5) $ 55,612.2 Cash Flows Used for Investments in Plant $ 1,668.1 $ 844.1 $ 1,406.3 $ 167.0 $ 251.3 $ — $ 4,336.8 For the Year Ended December 31, 2022 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Operating Revenues $ 9,405.3 $ 2,215.6 $ 1,808.7 $ 222.5 $ 1,435.5 $ (2,798.3) $ 12,289.3 Depreciation and Amortization (970.4) (157.6) (337.4) (50.9) (132.6) 5.8 (1,643.1) Other Operating Expenses (7,663.7) (1,727.0) (548.4) (111.8) (1,189.1) 2,792.0 (8,448.0) Operating Income 771.2 331.0 922.9 59.8 113.8 (0.5) 2,198.2 Interest Expense (253.1) (71.4) (145.5) (34.7) (247.8) 74.2 (678.3) Interest Income 45.1 10.2 0.5 — 66.3 (71.6) 50.5 Other Income, Net 180.4 33.6 37.9 8.5 1,600.8 (1,565.6) 295.6 Income Tax (Expense)/Benefit (146.2) (69.2) (216.3) 3.2 (25.1) — (453.6) Net Income 597.4 234.2 599.5 36.8 1,508.0 (1,563.5) 1,412.4 Net Income Attributable to Noncontrolling Interests (4.6) — (2.9) — — — (7.5) Net Income Attributable to Common Shareholders $ 592.8 $ 234.2 $ 596.6 $ 36.8 $ 1,508.0 $ (1,563.5) $ 1,404.9 Total Assets (as of) $ 27,365.0 $ 8,084.9 $ 13,369.5 $ 2,783.8 $ 26,365.2 $ (24,737.5) $ 53,230.9 Cash Flows Used for Investments in Plant $ 1,172.6 $ 710.3 $ 1,144.0 $ 154.4 $ 260.6 $ — $ 3,441.9 For the Year Ended December 31, 2021 Eversource (Millions of Dollars) Electric Natural Gas Electric Water Distribution Other Eliminations Total Operating Revenues $ 7,423.6 $ 1,789.6 $ 1,634.6 $ 211.3 $ 1,354.0 $ (2,550.0) $ 9,863.1 Depreciation and Amortization (737.8) (142.3) (300.3) (46.1) (113.1) 4.6 (1,335.0) Other Operating Expenses (5,970.0) (1,345.4) (496.2) (101.4) (1,170.4) 2,548.6 (6,534.8) Operating Income 715.8 301.9 838.1 63.8 70.5 3.2 1,993.3 Interest Expense (236.4) (58.6) (133.2) (32.0) (168.8) 46.6 (582.4) Interest Income 20.7 4.5 2.2 — 46.0 (47.8) 25.6 Other Income, Net 78.1 17.9 19.8 3.3 1,363.9 (1,347.3) 135.7 Income Tax (Expense)/Benefit (103.5) (60.9) (179.4) 1.7 (2.1) — (344.2) Net Income 474.7 204.8 547.5 36.8 1,309.5 (1,345.3) 1,228.0 Net Income Attributable to Noncontrolling Interests (4.6) — (2.9) — — — (7.5) Net Income Attributable to Common Shareholders $ 470.1 $ 204.8 $ 544.6 $ 36.8 $ 1,309.5 $ (1,345.3) $ 1,220.5 Cash Flows Used for Investments in Plant $ 1,053.3 $ 721.1 $ 1,024.1 $ 137.2 $ 239.4 $ — $ 3,175.1

GOODWILL (Tables)

GOODWILL (Tables)	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Goodwill by Reportable Segment	The following table presents Eversource’s goodwill by reportable segment: (Millions of Dollars) Electric Electric Natural Gas Water Total Balance as of January 1, 2022 $ 2,543.6 $ 576.8 $ 451.0 $ 905.9 $ 4,477.3 NESC Measurement Period Adjustments — — — 0.5 0.5 Acquisition of TWC — — — 44.8 44.8 Balance as of December 31, 2022 $ 2,543.6 $ 576.8 $ 451.0 $ 951.2 $ 4,522.6 Water Acquisitions — — — 9.5 9.5 Balance as of December 31, 2023 $ 2,543.6 $ 576.8 $ 451.0 $ 960.7 $ 4,532.1

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands, customer in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) project regulatedUtility customer	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Summary of Accounting Policies [Line Items]
Number of electric and natural gas customers | customer	4.4
Number of offshore wind projects | project	3
Number of tax equity projects | project	1
Goodwill	$ 4,532,100	$ 4,522,632	$ 4,477,300
Charitable contributions	$ 20,000	8,000
Offshore Wind Business
Summary of Accounting Policies [Line Items]
Ownership interest (in percent)	50%
Number of offshore wind projects | project	2
Tax Equity
Summary of Accounting Policies [Line Items]
Ownership interest (in percent)	50%
Energy Relief Fund
Summary of Accounting Policies [Line Items]
Restricted cash, current	$ 20,000	20,000
Restricted cash, noncurrent	$ 14,100	15,900
CL&P
Summary of Accounting Policies [Line Items]
Period of accounts receivable recoverable under financial or medical duress	180 days
Maximum loans receivable outstanding	$ 55,000
Loans transferred receivable current	8,500	9,100
Loans transferred receivable non-current	$ 14,500	13,000
Long term receivable		25,000
Yankee Gas Services Company
Summary of Accounting Policies [Line Items]
Period of accounts receivable recoverable under financial or medical duress	90 days
NSTAR Electric
Summary of Accounting Policies [Line Items]
Long term receivable		5,500
PSNH
Summary of Accounting Policies [Line Items]
Long term receivable		$ 3,800
Connecticut, Massachusetts and New Hampshire
Summary of Accounting Policies [Line Items]
Number of regulated utilities | regulatedUtility	12

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Allowance for Uncollectible Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 486,300	$ 417,400	$ 358,900
Uncollectible Expense	72,468	61,876	60,886
Uncollectible Costs Deferred	158,200	112,500	110,600
Write-Offs	(178,100)	(124,000)	(129,700)
Recoveries Collected	15,600	18,500	16,700
Ending Balance	554,500	486,300	417,400
Hardship Accounts
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	284,400	226,100	194,800
Uncollectible Expense	0	0	0
Uncollectible Costs Deferred	137,000	77,800	51,900
Write-Offs	(55,900)	(21,300)	(22,000)
Recoveries Collected	1,300	1,800	1,400
Ending Balance	366,800	284,400	226,100
Retail (Non-Hardship), Wholesale, and Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	201,900	191,300	164,100
Uncollectible Expense	72,500	61,900	60,900
Uncollectible Costs Deferred	21,200	34,700	58,700
Write-Offs	(122,200)	(102,700)	(107,700)
Recoveries Collected	14,300	16,700	15,300
Ending Balance	187,700	201,900	191,300
CL&P
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	225,300	181,300	157,400
Uncollectible Expense	11,675	15,578	13,495
Uncollectible Costs Deferred	126,400	59,500	57,800
Write-Offs	(73,200)	(38,300)	(54,200)
Recoveries Collected	5,800	7,200	6,800
Ending Balance	296,000	225,300	181,300
CL&P | Hardship Accounts
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	188,900	144,600	129,100
Uncollectible Expense	0	0	0
Uncollectible Costs Deferred	114,400	58,300	32,300
Write-Offs	(44,700)	(15,300)	(18,000)
Recoveries Collected	1,100	1,300	1,200
Ending Balance	259,700	188,900	144,600
CL&P | Retail (Non-Hardship), Wholesale, and Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	36,400	36,700	28,300
Uncollectible Expense	11,700	15,600	13,500
Uncollectible Costs Deferred	12,000	1,200	25,500
Write-Offs	(28,500)	(23,000)	(36,200)
Recoveries Collected	4,700	5,900	5,600
Ending Balance	36,300	36,400	36,700
NSTAR Electric
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	95,000	97,000	91,600
Uncollectible Expense	22,791	21,550	16,649
Uncollectible Costs Deferred	17,500	12,400	20,100
Write-Offs	(43,300)	(42,300)	(37,000)
Recoveries Collected	5,000	6,300	5,700
Ending Balance	97,000	95,000	97,000
NSTAR Electric | Hardship Accounts
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	43,700	43,300	39,700
Uncollectible Expense	0	0	0
Uncollectible Costs Deferred	1,500	1,500	4,300
Write-Offs	(1,600)	(1,100)	(700)
Recoveries Collected	0	0	0
Ending Balance	43,600	43,700	43,300
NSTAR Electric | Retail (Non-Hardship), Wholesale, and Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	51,300	53,700	51,900
Uncollectible Expense	22,800	21,600	16,600
Uncollectible Costs Deferred	16,000	10,900	15,800
Write-Offs	(41,700)	(41,200)	(36,300)
Recoveries Collected	5,000	6,300	5,700
Ending Balance	53,400	51,300	53,700
PSNH
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	29,200	24,300	17,200
Uncollectible Expense	3,989	9,211	13,113
Uncollectible Costs Deferred	(8,700)	2,500	3,100
Write-Offs	(10,900)	(7,700)	(10,000)
Recoveries Collected	700	900	900
Ending Balance	$ 14,300	$ 29,200	$ 24,300

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Materials, Supplies, Natural Gas, and REC Inventory (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Public Utilities, Inventory [Line Items]
Total	$ 507.3	$ 374.4
Materials and Supplies
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	397.9	221
Natural Gas
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	65.5	95.9
RECs
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	43.9	57.5
CL&P
Public Utilities, Inventory [Line Items]
Total	156.5	88.2
CL&P | Materials and Supplies
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	156.2	88.2
CL&P | Natural Gas
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	0	0
CL&P | RECs
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	0.3	0
NSTAR Electric
Public Utilities, Inventory [Line Items]
Total	173.8	138.4
NSTAR Electric | Materials and Supplies
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	130.8	81
NSTAR Electric | Natural Gas
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	0	0
NSTAR Electric | RECs
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	43	57.4
PSNH
Public Utilities, Inventory [Line Items]
Total	77.1	34.5
PSNH | Materials and Supplies
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	76.5	34.4
PSNH | Natural Gas
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	0	0
PSNH | RECs
Public Utilities, Inventory [Line Items]
Other inventory, capitalized costs, gross	$ 0.6	$ 0.1

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Operating Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Eversource - Cost of Natural Gas	$ 792.2	$ 1,010.2	$ 718.6

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of AFUDC and Weighted Average AFUDC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of Other Operating Costs and Expense [Line Items]
Borrowed Funds	$ 44.6	$ 21.8	$ 18.4
Equity Funds	78.1	47.3	37.3
Total AFUDC	$ 122.7	$ 69.1	$ 55.7
Average AFUDC Rate (in percent)	5.80%	4.70%	4.20%
CL&P
Components of Other Operating Costs and Expense [Line Items]
Borrowed Funds	$ 7.7	$ 4.8	$ 2.9
Equity Funds	20	13.6	7.7
Total AFUDC	$ 27.7	$ 18.4	$ 10.6
Average AFUDC Rate (in percent)	6.70%	6.60%	5%
NSTAR Electric
Components of Other Operating Costs and Expense [Line Items]
Borrowed Funds	$ 17.2	$ 10.7	$ 9
Equity Funds	45.7	24.6	20.4
Total AFUDC	$ 62.9	$ 35.3	$ 29.4
Average AFUDC Rate (in percent)	5.90%	5.40%	4.90%
PSNH
Components of Other Operating Costs and Expense [Line Items]
Borrowed Funds	$ 6.1	$ 1.4	$ 0.8
Equity Funds	5.4	2.5	1.6
Total AFUDC	$ 11.5	$ 3.9	$ 2.4
Average AFUDC Rate (in percent)	5.10%	2.60%	2.50%

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary of Accounting Policies [Line Items]
Other Income, Net	$ 348,069	$ 346,088	$ 161,282
Unrealized gain associated with investment	15,500	22,900	14,200
Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion
Summary of Accounting Policies [Line Items]
Other Income, Net	132,900	219,800	84,400
AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	78,100	47,300	37,300
Equity in Earnings of Unconsolidated Affiliates
Summary of Accounting Policies [Line Items]
Other Income, Net	15,500	22,900	14,200
Unrealized gain associated with investment		12,200	2,100
Investment (Loss)/Income
Summary of Accounting Policies [Line Items]
Other Income, Net	(4,900)	1,900	(200)
Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	94,200	50,500	25,600
Other
Summary of Accounting Policies [Line Items]
Other Income, Net	32,300	3,700	0
CL&P
Summary of Accounting Policies [Line Items]
Other Income, Net	61,560	83,252	30,187
CL&P | Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion
Summary of Accounting Policies [Line Items]
Other Income, Net	34,900	64,400	15,200
CL&P | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	20,000	13,600	7,700
CL&P | Investment (Loss)/Income
Summary of Accounting Policies [Line Items]
Other Income, Net	(2,400)	(1,300)	1,300
CL&P | Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	9,000	6,500	5,900
CL&P | Other
Summary of Accounting Policies [Line Items]
Other Income, Net	100	100	100
NSTAR Electric
Summary of Accounting Policies [Line Items]
Other Income, Net	164,129	142,661	74,844
NSTAR Electric | Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion
Summary of Accounting Policies [Line Items]
Other Income, Net	57,400	85,500	40,200
NSTAR Electric | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	45,700	24,600	20,400
NSTAR Electric | Investment (Loss)/Income
Summary of Accounting Policies [Line Items]
Other Income, Net	(200)	1,200	100
NSTAR Electric | Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	60,600	30,700	13,400
NSTAR Electric | Other
Summary of Accounting Policies [Line Items]
Other Income, Net	600	700	700
PSNH
Summary of Accounting Policies [Line Items]
Other Income, Net	26,597	32,666	14,565
PSNH | Pension, SERP and PBOP Non-Service Income Components, Net of Deferred Portion
Summary of Accounting Policies [Line Items]
Other Income, Net	16,200	26,800	10,300
PSNH | AFUDC Equity
Summary of Accounting Policies [Line Items]
Other Income, Net	5,400	2,500	1,600
PSNH | Investment (Loss)/Income
Summary of Accounting Policies [Line Items]
Other Income, Net	(700)	200	100
PSNH | Interest Income
Summary of Accounting Policies [Line Items]
Other Income, Net	5,300	3,100	2,400
PSNH | Other
Summary of Accounting Policies [Line Items]
Other Income, Net	$ 400	$ 100	$ 200

SUMMARY OF SIGNIFICANT ACCOU_10

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Other Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary of Accounting Policies [Line Items]
Excise and sales taxes	$ 202.9	$ 194.7	$ 181.9
CL&P
Summary of Accounting Policies [Line Items]
Excise and sales taxes	$ 174.9	$ 166.1	$ 158.1

SUMMARY OF SIGNIFICANT ACCOU_11

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Paid During the Year for:
Interest, Net of Amounts Capitalized	$ 783.2	$ 636.2	$ 568.7
Income Taxes	39.2	77.9	121.6
Non-Cash Investing Activities:
Plant Additions Included in Accounts Payable (As of)	564.1	586.9	467.9
CL&P
Cash Paid During the Year for:
Interest, Net of Amounts Capitalized	176.8	167.2	161.5
Income Taxes	(44.1)	117.6	38.4
Non-Cash Investing Activities:
Plant Additions Included in Accounts Payable (As of)	139.8	131.8	110.6
NSTAR Electric
Cash Paid During the Year for:
Interest, Net of Amounts Capitalized	182.8	152.8	141.6
Income Taxes	31.3	23.8	74.2
Non-Cash Investing Activities:
Plant Additions Included in Accounts Payable (As of)	178.9	184.3	120
PSNH
Cash Paid During the Year for:
Interest, Net of Amounts Capitalized	62.8	58.3	56.5
Income Taxes	(59.9)	58.3	51.1
Non-Cash Investing Activities:
Plant Additions Included in Accounts Payable (As of)	$ 65.9	$ 76.2	$ 68.7

SUMMARY OF SIGNIFICANT ACCOU_12

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents as reported on the Balance Sheets	$ 53,900	$ 374,600
Cash, Cash Equivalents and Restricted Cash as reported on the Statements of Cash Flows	166,418	521,752	$ 221,008	$ 264,950
CL&P
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents as reported on the Balance Sheets	10,200	11,300
Cash, Cash Equivalents and Restricted Cash as reported on the Statements of Cash Flows	12,243	20,327	74,788	99,809
NSTAR Electric
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents as reported on the Balance Sheets	6,700	327,700
Cash, Cash Equivalents and Restricted Cash as reported on the Statements of Cash Flows	22,785	345,293	18,179	17,410
PSNH
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents as reported on the Balance Sheets	200	100
Cash, Cash Equivalents and Restricted Cash as reported on the Statements of Cash Flows	35,004	36,812	$ 35,126	$ 39,555
Special Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	81,500	102,200
Special Deposits | CL&P
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	2,000	8,800
Special Deposits | NSTAR Electric
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	16,100	17,500
Special Deposits | PSNH
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	31,600	33,100
Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	13,700	25,400
Marketable Securities | CL&P
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	200
Marketable Securities | NSTAR Electric
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	100
Marketable Securities | PSNH
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	400
Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	17,300	19,600
Other Long-Term Assets | CL&P
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	0
Other Long-Term Assets | NSTAR Electric
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	0
Other Long-Term Assets | PSNH
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	Dec. 31, 2023	Dec. 31, 2022
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 6,389,200	$ 5,578,300
Less:  Current Portion	1,674,196	1,335,491
Total Long-Term Regulatory Assets	4,714,970	4,242,794
Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	1,785,900	1,379,100
Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	1,319,200	1,075,300
Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	1,117,300	921,700
Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	912,400	853,300
Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	392,500	435,700
Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	264,100	281,000
Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	137,900	127,900
Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	120,900	181,800
Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	339,000	322,500
CL&P
Regulatory Assets [Line Items]
Total Regulatory Assets	2,143,200	1,907,800
Less:  Current Portion	480,369	314,089
Total Long-Term Regulatory Assets	1,662,778	1,593,693
CL&P | Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	896,600	799,300
CL&P | Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	354,500	216,800
CL&P | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	197,400	156,700
CL&P | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	512,600	491,100
CL&P | Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
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	38,500	35,900
CL&P | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	120,900	181,800
CL&P | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	22,700	26,200
NSTAR Electric
Regulatory Assets [Line Items]
Total Regulatory Assets	1,957,900	1,714,400
Less:  Current Portion	676,083	492,759
Total Long-Term Regulatory Assets	1,281,836	1,221,619
NSTAR Electric | Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	609,100	484,400
NSTAR Electric | Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	482,900	391,500
NSTAR Electric | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	336,700	299,500
NSTAR Electric | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	128,600	115,600
NSTAR Electric | Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric | Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	226,700	241,200
NSTAR Electric | Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	72,300	68,200
NSTAR Electric | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	101,600	114,000
PSNH
Regulatory Assets [Line Items]
Total Regulatory Assets	963,300	696,200
Less:  Current Portion	189,450	102,240
Total Long-Term Regulatory Assets	773,783	593,974
PSNH | Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	280,200	95,400
PSNH | Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	182,200	73,700
PSNH | Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	79,300	56,600
PSNH | Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	16,400	16,000
PSNH | Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	392,500	435,700
PSNH | Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH | Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	4,700	4,400
PSNH | Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 8,000	$ 14,400

REGULATORY ACCOUNTING - Narrati

REGULATORY ACCOUNTING - Narrative (Details)

4 Months Ended

12 Months Ended

37 Months Ended

Dec. 26, 2023 USD ($)

Oct. 30, 2023 USD ($)

May 01, 2023 USD ($)

Jan. 01, 2023 USD ($)

Nov. 30, 2022 USD ($)

Oct. 31, 2022 USD ($)

Apr. 30, 2023 USD ($)

Dec. 31, 2023 USD ($) storm

Dec. 31, 2022 USD ($) storm

Dec. 31, 2021 USD ($)

Dec. 31, 2021 weather_event

Dec. 22, 2023 USD ($)

Mar. 31, 2023 USD ($)

May 31, 2018 USD ($)

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

$ 241,700,000

$ 210,800,000

Deferred costs

82,100,000

64,000,000

Gain (loss) related to litigation settlement

0

72,041,000

$ (81,274,000)

Regulatory assets

6,389,200,000

5,578,300,000

Increase (decrease) in regulatory assets

151,548,000

205,294,000

314,211,000

FERC ROE Complaints

Regulatory Assets [Line Items]

Cumulative pre-tax reserves which include impact of refunds given to customers

39,100,000

39,100,000

Unfavorable Regulatory Action

Regulatory Assets [Line Items]

Gain (loss) related to litigation settlement

(103,600,000)

Unfavorable Regulatory Action | Oil and Gas, Operation and Maintenance

Regulatory Assets [Line Items]

Gain (loss) related to litigation settlement

(10,000,000)

Deferred Pre-Staging And Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

542,000,000

Deferred Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

$ 1,750,000,000

Goodwill-related

Regulatory Assets [Line Items]

Recovery period (in years)

40 years

Remaining amortization (in years)

16 years

Regulatory assets

$ 264,100,000

281,000,000

PSNH

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

1,200,000

1,000,000

Equity return not recorded on the balance sheet

10,200,000

4,100,000

Regulatory assets

963,300,000

696,200,000

Increase (decrease) in regulatory assets

273,472,000

(53,181,000)

(32,587,000)

PSNH | FERC ROE Complaints

Regulatory Assets [Line Items]

Cumulative pre-tax reserves which include impact of refunds given to customers

3,100,000

3,100,000

PSNH | Deferred Pre-Staging And Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

172,000,000

PSNH | Deferred Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

246,000,000

PSNH | Goodwill-related

Regulatory Assets [Line Items]

Regulatory assets

0

0

PSNH | Operation, Maintenance And Vegetation Expenses

Regulatory Assets [Line Items]

Regulatory assets

$ 16,900,000

Purchase price of regulatory assets

$ 23,300,000

CL&P

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

166,700,000

135,900,000

Deferred costs

64,000,000

52,800,000

Average monthly bill

$ 10

Public utilities, approved rate increase (decrease), net revenues generated

$ 90,000,000

Gain (loss) related to litigation settlement

0

72,041,000

(81,274,000)

Regulatory assets

2,143,200,000

1,907,800,000

Increase (decrease) in regulatory assets

(157,200,000)

144,793,000

152,775,000

CL&P | Energy Assistance Program

Regulatory Assets [Line Items]

Restricted cash

$ 10,000,000

CL&P | FERC ROE Complaints

Regulatory Assets [Line Items]

Cumulative pre-tax reserves which include impact of refunds given to customers

21,400,000

21,400,000

CL&P | Unfavorable Regulatory Action | Oil and Gas, Operation and Maintenance

Regulatory Assets [Line Items]

Gain (loss) related to litigation settlement

(10,000,000)

CL&P | Deferred Pre-Staging And Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

178,000,000

CL&P | Deferred Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

975,000,000

CL&P | Deferred Storm Restoration Costs | Tropical Storm Isaias

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

232,000,000

CL&P | Goodwill-related

Regulatory Assets [Line Items]

Regulatory assets

0

0

CL&P | Catastrophic Storm Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

$ 634,000,000

Number of catastrophic weather events | weather_event

24

Annual amount of regulatory costs collected

$ 50,000,000

NSTAR Electric

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

21,900,000

19,800,000

Deferred costs

$ 7,300,000

$ 3,500,000

Rate increase approved

$ 104,900,000

$ 64,000,000

Renewal term of performance-based ratemaking plan (in years)

5 years

Extension period (in years)

5 years

Historical average term of capital additions (in years)

5 years

5 years

Authorized regulatory ROE (in percent)

9.80%

Authorized common equity ratio (in percent)

53.20%

Regulatory assets

$ 1,957,900,000

$ 1,714,400,000

Increase (decrease) in regulatory assets

$ 141,865,000

$ 88,220,000

$ 79,075,000

Storms in a calendar year | storm

8

Storms recovered at base rate | storm

6

Number of additional storms | storm

2

NSTAR Electric | FERC ROE Complaints

Regulatory Assets [Line Items]

Cumulative pre-tax reserves which include impact of refunds given to customers

$ 14,600,000

$ 14,600,000

NSTAR Electric | Deferred Pre-Staging And Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

192,000,000

NSTAR Electric | Deferred Storm Restoration Costs

Regulatory Assets [Line Items]

Amount of regulatory costs not yet approved

526,000,000

NSTAR Electric | Goodwill-related

Regulatory Assets [Line Items]

Regulatory assets

$ 226,700,000

241,200,000

NSTAR Electric | Storm Fund Contribution

Regulatory Assets [Line Items]

Regulatory assets

10,000,000

Increase (decrease) in regulatory assets

31,000,000

NSTAR Electric | Storm Threshold Costs

Regulatory Assets [Line Items]

Regulatory assets

1,300,000

NSTAR Electric | Recovery of Storm Costs

Regulatory Assets [Line Items]

Regulatory assets

$ 162,100,000

Recovery period of regulatory asset (in years)

5 years

NSTAR Electric | Recovery of exogenous storms

Regulatory Assets [Line Items]

Regulatory assets

$ 220,900,000

Recovery period of regulatory asset (in years)

5 years

NSTAR Electric | Recovery of historical exogenous property taxes from 2020 - 2022

Regulatory Assets [Line Items]

Regulatory assets

$ 30,800,000

Recovery period of regulatory asset (in years)

2 years

NSTAR Electric | Recovery of historical exogenous property taxes from 2012 - 2015

Regulatory Assets [Line Items]

Regulatory assets

$ 8,300,000

Recovery period of regulatory asset (in years)

5 years

NSTAR Electric | Inflation Based Adjustment

Regulatory Assets [Line Items]

Rate increase approved

50,600,000

NSTAR Electric | K-Bar Adjustment

Regulatory Assets [Line Items]

Rate increase approved

$ 54,300,000

NSTAR Gas

Regulatory Assets [Line Items]

Rate increase approved

$ 25,400,000

$ 21,700,000

NSTAR Gas | Exogenous Property Taxes

Regulatory Assets [Line Items]

Rate increase approved

4,500,000

NSTAR Gas | Mitigation Plan

Regulatory Assets [Line Items]

Rate increase approved

5,400,000

NSTAR Gas | Recovery of Exogenous Property Taxes

Regulatory Assets [Line Items]

Regulatory assets

$ 8,200,000

Recovery period of regulatory asset (in years)

2 years

NSTAR Gas | Base Rate Adjustment

Regulatory Assets [Line Items]

Rate increase approved

$ 15,500,000

EGMA

Regulatory Assets [Line Items]

Rate increase approved

$ 6,700,000

EGMA | Tax Act Credit Factor

Regulatory Assets [Line Items]

Rate increase approved

3,300,000

EGMA | Recovery of Exogenous Property Taxes

Regulatory Assets [Line Items]

Regulatory assets

$ 8,600,000

Recovery period of regulatory asset (in years)

2 years

Rate Reduction Bonds | PSNH

Regulatory Assets [Line Items]

Amount of securitized rate reduction bonds issued

$ 635,700,000

REGULATORY ACCOUNTING - Compo_2

REGULATORY ACCOUNTING - Components of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 4,614,700	$ 4,821,100
Less:  Current Portion	591,750	890,786
Total Long-Term Regulatory Liabilities	4,022,923	3,930,305
EDIT due to Tax Cuts and Jobs Act of 2017
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	2,548,600	2,619,300
Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	666,600	670,600
Regulatory Tracking Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	668,300	890,800
Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	354,000	270,900
AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	124,300	98,200
Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	51,000	55,400
Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	201,900	215,900
CL&P
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,418,100	1,599,400
Less:  Current Portion	102,239	336,048
Total Long-Term Regulatory Liabilities	1,315,928	1,263,396
CL&P | EDIT due to Tax Cuts and Jobs Act of 2017
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	969,200	983,600
CL&P | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	157,900	130,800
CL&P | Regulatory Tracking Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	154,000	361,000
CL&P | Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	49,900	34,500
CL&P | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	56,100	48,200
CL&P | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	600	700
CL&P | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	30,400	40,600
NSTAR Electric
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,953,400	1,921,300
Less:  Current Portion	368,070	373,221
Total Long-Term Regulatory Liabilities	1,585,311	1,548,081
NSTAR Electric | EDIT due to Tax Cuts and Jobs Act of 2017
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	905,100	944,300
NSTAR Electric | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	420,900	405,300
NSTAR Electric | Regulatory Tracking Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	347,200	336,100
NSTAR Electric | Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	175,900	139,700
NSTAR Electric | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	68,200	50,000
NSTAR Electric | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	22,200	31,400
NSTAR Electric | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	13,900	14,500
PSNH
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	511,100	553,600
Less:  Current Portion	117,515	161,963
Total Long-Term Regulatory Liabilities	393,574	391,628
PSNH | EDIT due to Tax Cuts and Jobs Act of 2017
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	339,300	348,600
PSNH | Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	16,200	14,700
PSNH | Regulatory Tracking Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	114,400	155,000
PSNH | Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	36,600	28,800
PSNH | AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH | Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 4,600	$ 6,500

PROPERTY, PLANT AND EQUIPMENT_3

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION - Investment in Utility Property, Plant and Equipment By Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Distribution - Electric	$ 19,656,500	$ 18,326,200
Distribution - Natural Gas	8,155,300	7,443,800
Transmission - Electric	14,666,800	13,709,300
Distribution - Water	2,280,100	2,112,600
Solar	201,100	200,800
Utility	44,959,800	41,792,700
Other	2,006,800	1,738,100
Property, Plant and Equipment, Gross	46,966,600	43,530,800
Less:  Accumulated Depreciation
Utility	(9,670,100)	(9,167,400)
Other	(869,600)	(706,100)
Total Accumulated Depreciation	(10,539,700)	(9,873,500)
Property, Plant and Equipment, Net	36,426,900	33,657,300
Construction Work in Progress	3,071,700	2,455,500
Total Property, Plant and Equipment, Net	39,498,607	36,112,820
CL&P
Property, Plant and Equipment [Line Items]
Distribution - Electric	7,897,100	7,370,100
Transmission - Electric	6,548,200	6,165,100
Solar	0	0
Property, Plant and Equipment, Gross	14,445,300	13,535,200
Less:  Accumulated Depreciation
Total Accumulated Depreciation	(2,670,500)	(2,567,100)
Property, Plant and Equipment, Net	11,774,800	10,968,100
Construction Work in Progress	565,400	498,900
Total Property, Plant and Equipment, Net	12,340,192	11,467,024
NSTAR Electric
Property, Plant and Equipment [Line Items]
Distribution - Electric	9,000,500	8,410,000
Transmission - Electric	5,630,800	5,333,800
Solar	201,100	200,800
Property, Plant and Equipment, Gross	14,832,400	13,944,600
Less:  Accumulated Depreciation
Total Accumulated Depreciation	(3,585,900)	(3,381,200)
Property, Plant and Equipment, Net	11,246,500	10,563,400
Construction Work in Progress	1,507,300	1,063,600
Total Property, Plant and Equipment, Net	12,753,787	11,626,968
PSNH
Property, Plant and Equipment [Line Items]
Distribution - Electric	2,799,200	2,586,400
Transmission - Electric	2,489,500	2,212,000
Solar	0	0
Property, Plant and Equipment, Gross	5,288,700	4,798,400
Less:  Accumulated Depreciation
Total Accumulated Depreciation	(984,000)	(912,300)
Property, Plant and Equipment, Net	4,304,700	3,886,100
Construction Work in Progress	270,000	174,100
Total Property, Plant and Equipment, Net	$ 4,574,652	$ 4,060,224

PROPERTY, PLANT AND EQUIPMENT_4

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION - Schedule of Aggregate Composite Depreciation Rates (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Composite depreciation rate for plant in service (in percent)	3.10%	3%	3.10%
CL&P
Property, Plant and Equipment [Line Items]
Composite depreciation rate for plant in service (in percent)	2.80%	2.80%	2.80%
NSTAR Electric
Property, Plant and Equipment [Line Items]
Composite depreciation rate for plant in service (in percent)	2.70%	2.70%	2.80%
PSNH
Property, Plant and Equipment [Line Items]
Composite depreciation rate for plant in service (in percent)	3%	3%	3.10%

PROPERTY, PLANT AND EQUIPMENT_5

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION - Schedule of Average Remaining Useful Lives of Depreciable Assets (Details)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Distribution - Electric	34 years
Distribution - Natural Gas	35 years 8 months 12 days
Transmission - Electric	40 years 7 months 6 days
Distribution - Water	40 years
Solar	22 years 9 months 18 days
Other	10 years 4 months 24 days
Computer Software, Hardware and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment (in years)	5 years
Computer Software, Hardware and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment (in years)	15 years
Buildings
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment (in years)	40 years
CL&P
Property, Plant and Equipment [Line Items]
Distribution - Electric	35 years 3 months 18 days
Transmission - Electric	37 years 1 month 6 days
NSTAR Electric
Property, Plant and Equipment [Line Items]
Distribution - Electric	34 years 6 months
Transmission - Electric	45 years 3 months 18 days
Solar	22 years 9 months 18 days
PSNH
Property, Plant and Equipment [Line Items]
Distribution - Electric	29 years 7 months 6 days
Transmission - Electric	41 years 4 months 24 days

DERIVATIVE INSTRUMENTS - Schedu

DERIVATIVE INSTRUMENTS - Schedule of Gross Fair Value of Contracts (Details) - CL&P - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Level 3 | Current Derivative Assets
Current and Long-Term Derivative Assets
Commodity Supply and Price Risk Management		$ 16.3
Netting		(0.5)
Net Amount Recorded as a Derivative		15.8
Level 3 | Long-Term Derivative Assets
Current and Long-Term Derivative Assets
Commodity Supply and Price Risk Management		28.8
Netting		(0.9)
Net Amount Recorded as a Derivative		27.9
Level 3 | Current Derivative Liabilities
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management		(81.6)
Netting		0
Net Amount Recorded as a Derivative		(81.6)
Level 3 | Long-Term Derivative Liabilities
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management		(143.9)
Netting		0
Net Amount Recorded as a Derivative		$ (143.9)
Level 2 | Current Derivative Assets
Current and Long-Term Derivative Assets
Commodity Supply and Price Risk Management	$ 16.4
Netting	(0.5)
Net Amount Recorded as a Derivative	15.9
Level 2 | Long-Term Derivative Assets
Current and Long-Term Derivative Assets
Commodity Supply and Price Risk Management	13.6
Netting	(0.5)
Net Amount Recorded as a Derivative	13.1
Level 2 | Current Derivative Liabilities
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(81.9)
Netting	0
Net Amount Recorded as a Derivative	(81.9)
Level 2 | Long-Term Derivative Liabilities
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(68)
Netting	0
Net Amount Recorded as a Derivative	$ (68)

DERIVATIVE INSTRUMENTS - Narrat

DERIVATIVE INSTRUMENTS - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) MW	Dec. 31, 2022 USD ($) $ / KWmo MW	Dec. 31, 2021 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of costs or benefits borne under capacity-related contracts by United Illuminated Company (as a percentage)	20%
Amount of power to be purchased under capacity-related contract (up to) (in MW) | MW	682	674
Gain (loss) on deferred regulatory costs | $	$ (3.9)	$ 10.1	$ (7.1)
CL&P
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of costs or benefits borne under capacity-related contracts (as a percentage)	80%
Minimum | Level 3
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts		2.90%
Minimum | Level 3 | CL&P | Measurement Input, Forward Reserve
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input		0.44
Weighted Average | Level 3
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts		6.10%
Weighted Average | Level 3 | CL&P | Measurement Input, Forward Reserve
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input		0.47
Maximum | Level 3
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts		7.10%
Maximum | Level 3 | CL&P | Measurement Input, Forward Reserve
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input		0.50

DERIVATIVE INSTRUMENTS - Variat

DERIVATIVE INSTRUMENTS - Variations Using Significant unobservable Inputs (Details) - Level 3 - CL&P - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value as of Beginning of Period	$ (181.8)	$ (249.2)
Net Realized/Unrealized (Losses)/Gains Included in Regulatory Assets	(3.9)	10.1
Settlements	64.8	57.3
Transfers out of Level 3 (1)	120.9	0
Fair Value as of End of Period	$ 0	$ (181.8)

MARKETABLE SECURITIES - Narrati

MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 3.3	$ 20
Equity securities, FV-NI, realized gain	1.1
Unrealized losses recorded in other income		9.7
Unrealized gains recorded in other income			$ 4.4
Unrealized Gains/(Losses) on Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Losses recorded on securities intended to be sold	1.2
CYAPC and YAEC
Debt Securities, Available-for-sale [Line Items]
Equity securities	173.6	170.1
Marketable securities held in nuclear decommissioning trusts	$ 164.3	$ 163.2

MARKETABLE SECURITIES - Availab

MARKETABLE SECURITIES - Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Amortized Cost	$ 169.5	$ 201.6
Pre-Tax Unrealized Gains	1.4	0.1
Pre-Tax Unrealized Losses	(6.6)	(16.2)
Fair Value	$ 164.3	$ 185.5

MARKETABLE SECURITIES - Contrac

MARKETABLE SECURITIES - Contractual Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Amortized Cost
Less than one year	$ 15.9
One to five years	30.9
Six to ten years	38.1
Greater than ten years	84.6
Amortized Cost	169.5	$ 201.6
Fair Value
Less than one year	15.9
One to five years	30.9
Six to ten years	37.8
Greater than ten years	79.7
Total Debt Securities	$ 164.3	$ 185.5

MARKETABLE SECURITIES - Fair Va

MARKETABLE SECURITIES - Fair Value Measurement (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	$ 341.2	$ 375.6
Level 1
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	190.6	215.5
Level 1 | Mutual Funds and Equities
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	176.9	190.1
Level 1 | Money Market Funds
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	13.7	25.4
Level 2
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	150.6	160.1
Level 2 | U.S. Government Issued Debt Securities (Agency and Treasury)
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	90.1	82.3
Level 2 | Corporate Debt Securities
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	34	46.1
Level 2 | Asset-Backed Debt Securities
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	5.6	8.6
Level 2 | Municipal Bonds
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	9.8	12.7
Level 2 | Other Fixed Income Securities
Debt and Equity Securities, FV-NI [Line Items]
Total Marketable Securities	$ 11.1	$ 10.4

INVESTMENTS IN UNCONSOLIDATED_3

INVESTMENTS IN UNCONSOLIDATED AFFILIATES - Summary of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Investments in Unconsolidated Affiliates	$ 660,473	$ 2,176,080
Offshore Wind Business
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)	50%
Investments in Unconsolidated Affiliates	$ 515,500	1,947,100
Offshore Wind Business | Minimum
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)	50%
Offshore Wind Business | Maximum
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)	100%
Natural Gas Pipeline - Algonquin Gas Transmission, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)	15%
Investments in Unconsolidated Affiliates	$ 116,000	118,800
Renewable Energy Investment Fund
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)	90%
Investments in Unconsolidated Affiliates	$ 0	84,100
Other
Schedule of Equity Method Investments [Line Items]
Investments in Unconsolidated Affiliates	$ 29,000	$ 26,100

INVESTMENTS IN UNCONSOLIDATED_4

INVESTMENTS IN UNCONSOLIDATED AFFILIATES - Narrative (Details) $ in Thousands			1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 12, 2024 USD ($)	Sep. 07, 2023 USD ($) a mile	Sep. 30, 2023 USD ($) turbine	Dec. 31, 2023 USD ($) project	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) project company	Dec. 31, 2022 USD ($) company	Dec. 31, 2021 USD ($)	Jan. 24, 2024
Schedule of Equity Method Investments [Line Items]
Equity in (Losses)/Earnings of Subsidiaries						$ 15,500	$ 22,900	$ 14,200
Dividends received from equity method investees						$ 20,100	26,200	21,600
Number of offshore wind projects | project				3		3
Payments to acquire investments						$ 1,680,473	742,496	327,385
Reduction of federal tax liability or generate tax refunds, period (in years)			24 months
Number of turbines | turbine			12
Investment tax credit, percent realized					0.10
Impairments of Offshore Wind Investments				$ 1,766,000	$ 401,000	2,167,000	$ 0	$ 0
Equity method investment, other than temporary impairment, after tax				$ 1,622,000	$ 331,000	1,953,000
Proceeds from sale, land, held-for-investment						$ 318,000
Number of companies that transmit hydro electricity imported from The Hydro-Quebec System in Canada | company						2	2
Subsequent Event
Schedule of Equity Method Investments [Line Items]
Investment tax credit, percent realized	0.10
Expected investment tax credit	$ 170,000
Sunrise Wind LLC | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Negotiation period (in days)									90 days
Offshore Wind Business - North East Offshore And Bay State Wind
Schedule of Equity Method Investments [Line Items]
Carrying amount of equity method investments in excess of the underlying equity in net assets							$ 343,100
Basis difference							$ 168,900
Hydro-Quebec System
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)				14.50%		14.50%	14.50%
Payments to acquire investments						$ 9,600	$ 9,300
South Fork Wind Holdings, LLC Class A
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)			100%
Impairments of Offshore Wind Investments				$ 4,000
Offshore Wind Business
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)				50%		50%
Number of offshore wind projects | project				2		2
Impairments of Offshore Wind Investments				$ 1,766,000
Uncommitted Lease Area
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)		50%
Land subject to ground leases | a		175,000
Number of miles off south coast of Massachusetts | mile		25
Payments to acquire investments		$ 625,000
Tax Equity Capital Contribution Agreement
Schedule of Equity Method Investments [Line Items]
Payments to acquire investments			$ 528,000
Sunrise Wind LLC
Schedule of Equity Method Investments [Line Items]
Impairments of Offshore Wind Investments				$ 1,218,000
Sunrise Wind LLC | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)									50%
Sunrise Wind LLC | Orsted | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Equity method investment, percent of purchase price paid at closing (in percent)									0.50
Equity method investment, percent of remaining purchase price paid (in percent)									0.50
Renewable Energy Investment Fund
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)				90%		90%
Proceeds from sale of equity method investments						$ 147,600
Renewable Energy Investment Fund | Equity Method Investee
Schedule of Equity Method Investments [Line Items]
Payments for charitable contributions						$ 20,000
South Fork Wind, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)				50%		50%
Northeast Offshore LLC and South Fork Class B Member, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)				50%		50%
Number of offshore wind projects | project				3		3
South Fork Wind And Revolution Wind | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percent)	50%
Proceeds from sale of equity method investments	$ 1,100,000
Cost sharing agreement, threshold amount	$ 240,000

INVESTMENTS IN UNCONSOLIDATED_5

INVESTMENTS IN UNCONSOLIDATED AFFILIATES - Summary of Impairment (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023 USD ($) project	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) project	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of offshore wind projects | project	3		3
Impairment Charges, pre-tax	$ 1,766,000	$ 401,000	$ 2,167,000	$ 0	$ 0
Tax Benefit	(144,000)	(70,000)	(214,000)
Equity method investment, other than temporary impairment, after tax	1,622,000	331,000	1,953,000
Lower expected sales proceeds across all three wind projects
Schedule of Equity Method Investments [Line Items]
Impairment Charges, pre-tax	525,000	401,000	926,000
Expected cost overruns not recovered in the sales price
Schedule of Equity Method Investments [Line Items]
Impairment Charges, pre-tax	441,000	0	441,000
Loss of sales value from the sale price offered by GIP, including loss of ITC adders value, cancellation costs and other impacts assuming Sunrise Wind project is abandoned
Schedule of Equity Method Investments [Line Items]
Impairment Charges, pre-tax	$ 800,000	$ 0	$ 800,000

INVESTMENTS IN UNCONSOLIDATED_6

INVESTMENTS IN UNCONSOLIDATED AFFILIATES - Summary of Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Impairments of Offshore Wind Investments	$ (1,766,000)	$ (401,000)	$ (2,167,000)	$ 0	$ 0
Carrying Value as of December 31, 2023	660,473		660,473	2,176,080
Sunrise Wind
Schedule of Equity Method Investments [Line Items]
Carrying Value as of December 31, 2023, before Impairment Charge	699,000		699,000
Impairments of Offshore Wind Investments	(1,218,000)
Carrying Value as of December 31, 2023	(519,000)		(519,000)
Revolution Wind
Schedule of Equity Method Investments [Line Items]
Carrying Value as of December 31, 2023, before Impairment Charge	799,000		799,000
Impairments of Offshore Wind Investments	(544,000)
Carrying Value as of December 31, 2023	255,000		255,000
South Fork Class B Member, LLC
Schedule of Equity Method Investments [Line Items]
Carrying Value as of December 31, 2023, before Impairment Charge	299,000		299,000
Impairments of Offshore Wind Investments	0
Carrying Value as of December 31, 2023	299,000		299,000
South Fork Wind Holdings, LLC Class A
Schedule of Equity Method Investments [Line Items]
Carrying Value as of December 31, 2023, before Impairment Charge	485,000		485,000
Impairments of Offshore Wind Investments	(4,000)
Carrying Value as of December 31, 2023	481,000		481,000
Total Offshore Wind Investments
Schedule of Equity Method Investments [Line Items]
Carrying Value as of December 31, 2023, before Impairment Charge	2,282,000		2,282,000
Impairments of Offshore Wind Investments	(1,766,000)
Carrying Value as of December 31, 2023	$ 515,500		$ 515,500	$ 1,947,100

ASSET RETIREMENT OBLIGATIONS -

ASSET RETIREMENT OBLIGATIONS - Schedule of Reconciliation of Beginning and Ending Balance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of Beginning of Year	$ 502.7	$ 500.1
Liabilities Settled During the Year	(24.9)	(22.3)
Accretion	29.2	28.9
Revisions in Estimated Cash Flows	(1.2)	(4)
Balance as of End of Year	505.8	502.7
CL&P
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of Beginning of Year	37.4	35
Liabilities Settled During the Year	0	0
Accretion	2.5	2.4
Revisions in Estimated Cash Flows	0	0
Balance as of End of Year	39.9	37.4
NSTAR Electric
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of Beginning of Year	101.3	97.5
Liabilities Settled During the Year	0	0
Accretion	4.3	4.1
Revisions in Estimated Cash Flows	(0.8)	(0.3)
Balance as of End of Year	104.8	101.3
PSNH
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of Beginning of Year	4.9	4.7
Liabilities Settled During the Year	0	0
Accretion	0.3	0.2
Revisions in Estimated Cash Flows	0	0
Balance as of End of Year	$ 5.2	$ 4.9

ASSET RETIREMENT OBLIGATIONS _2

ASSET RETIREMENT OBLIGATIONS - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Asset Retirement Obligation [Line Items]
Asset retirement obligations	$ 505.8	$ 502.7	$ 500.1
CYAPC and YAEC
Schedule of Asset Retirement Obligation [Line Items]
Asset retirement obligations	$ 315.8	$ 320.5

SHORT-TERM DEBT - Narrative (De

SHORT-TERM DEBT - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 18, 2023	Nov. 30, 2023
Short-term Debt [Line Items]
Long-Term Debt	$ 23,588,616,000	$ 19,723,994,000
Eversource
Short-term Debt [Line Items]
Long-Term Debt	9,952,351,000	6,972,804,000
Commercial Paper
Short-term Debt [Line Items]
Long-Term Debt	990,900,000
Commercial Paper | Eversource
Short-term Debt [Line Items]
Maximum borrowing capacity	2,000,000,000
Line of Credit
Short-term Debt [Line Items]
Amount outstanding during period	0	0
Line of Credit | Eversource
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 2,000,000,000
Debt instrument term (in years)	5 years
CL&P
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency				$ 600,000,000
Long-Term Debt	$ 4,814,429,000	4,216,488,000
Notes payable	249,670,000	0
CL&P | Related Party
Short-term Debt [Line Items]
Long-Term Debt	207,300,000
Notes payable	$ 457,000,000
CL&P | Unsecured Debt
Short-term Debt [Line Items]
Period of maturity restricting provisions of debt	10 years
Total capitalization (as a percentage)	10%
Capacity available under preferred stock provisions	$ 625,700,000
CL&P | Commercial Paper
Short-term Debt [Line Items]
Long-Term Debt	139,800,000	400,000,000
CL&P | Commercial Paper
Short-term Debt [Line Items]
Long-Term Debt	207,300,000
CL&P | Line of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	375,000,000
Borrowings outstanding	0
NSTAR Electric
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency			$ 655,000,000
Long-Term Debt	4,496,947,000	4,345,085,000
Notes payable	365,847,000	0
NSTAR Electric | Unsecured Debt
Short-term Debt [Line Items]
Long-Term Debt	4,400,000,000	4,250,000,000
NSTAR Electric | Commercial Paper
Short-term Debt [Line Items]
Maximum borrowing capacity	650,000,000
NSTAR Electric | Line of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 650,000,000
Debt instrument term (in years)	5 years
PSNH
Short-term Debt [Line Items]
Short-term borrowing limit approved by regulatory agency	$ 483,200,000
Long-Term Debt	1,431,591,000	1,134,914,000
Notes payable	233,000,000	173,300,000
PSNH | Related Party
Short-term Debt [Line Items]
Notes payable	$ 233,000,000	173,300,000
PSNH | Commercial Paper
Short-term Debt [Line Items]
Long-Term Debt		$ 295,300,000
PSNH | Short Term Debt Authorization Calculation
Short-term Debt [Line Items]
Interest rate	10%
Short-term debt borrowing calculation approved by regulatory agency	$ 60,000,000
PSNH | Line of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 250,000,000

SHORT-TERM DEBT - Schedule of D

SHORT-TERM DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Borrowings Outstanding as of December 31,	$ 1,930,422	$ 1,442,200
Eversource Parent Commercial Paper Program
Line of Credit Facility [Line Items]
Borrowings Outstanding as of December 31,	1,564,575	1,442,200
Commercial Paper | Eversource Parent Commercial Paper Program
Line of Credit Facility [Line Items]
Borrowings Outstanding as of December 31,	1,771,900	1,442,200
Available Borrowing Capacity as of December 31,	$ 228,100	$ 557,800
Weighted-Average Interest Rate as of December 31,	5.60%	4.63%
Commercial Paper | NSTAR Electric
Line of Credit Facility [Line Items]
Borrowings Outstanding as of December 31,	$ 365,800	$ 0
Available Borrowing Capacity as of December 31,	$ 284,200	$ 650,000
Weighted-Average Interest Rate as of December 31,	5.40%	0%

LONG-TERM DEBT - Schedule of Lo

LONG-TERM DEBT - Schedule of Long-Term Debt Outstanding (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Long-Term Debt	$ 23,588,616	$ 19,723,994
Less Amounts due Within One Year	(824,847)	(1,320,129)
Current Maturities Classified as Long-Term Debt	990,900	0
Senior Notes
Debt Instrument [Line Items]
Unamortized Premiums and Discounts, Net	49,700	40,100
Unamortized Debt Issuance Costs	(65,000)	(49,400)
Long-Term Debt	23,588,600	19,724,000
Pre-1983 Spent Nuclear Fuel Obligation (CYAPC)
Debt Instrument [Line Items]
Long-Term Debt	12,500	11,900
Fair Value Adjustment
Debt Instrument [Line Items]
Long-Term Debt	19,300	26,200
Fair Value Adjustment - Current Portion
Debt Instrument [Line Items]
Long-Term Debt	(5,500)	(7,000)
Loans Payable
Debt Instrument [Line Items]
Less Amounts due Within One Year	(1,810,200)	(1,203,400)
Total Other Long-Term Debt
Debt Instrument [Line Items]
Long-Term Debt	12,845,700	10,027,500
Commercial Paper
Debt Instrument [Line Items]
Long-Term Debt	990,900
Eversource
Debt Instrument [Line Items]
Long-Term Debt	9,952,351	6,972,804
Less Amounts due Within One Year	(364,653)	(1,207,047)
Eversource | Unsecured Debt | Eversource Parent - Senior Notes due 2024 - 2050
Debt Instrument [Line Items]
Long-Term Debt	$ 10,300,000	8,150,000
Eversource | Unsecured Debt | Eversource Parent - Senior Notes due 2024 - 2050 | Minimum
Debt Instrument [Line Items]
Interest rate	0.80%
Eversource | Unsecured Debt | Eversource Parent - Senior Notes due 2024 - 2050 | Maximum
Debt Instrument [Line Items]
Interest rate	5.95%
CL&P
Debt Instrument [Line Items]
Long-Term Debt	$ 4,814,429	4,216,488
Less Amounts due Within One Year	(139,800)	(400,000)
CL&P | First Mortgage Bonds
Debt Instrument [Line Items]
Long-Term Debt	4,619,800	4,219,800
Current Maturities Classified as Long-Term Debt	139,800	400,000
Unamortized Premiums and Discounts, Net	18,000	21,500
Unamortized Debt Issuance Costs	(30,700)	(24,800)
Long-Term Debt	$ 4,814,400	4,216,500
CL&P | First Mortgage Bonds | 1994 Series D due 2024
Debt Instrument [Line Items]
Interest rate	7.875%
Long-Term Debt	$ 139,800	139,800
CL&P | First Mortgage Bonds | 2004 Series B due 2034
Debt Instrument [Line Items]
Interest rate	5.75%
Long-Term Debt	$ 130,000	130,000
CL&P | First Mortgage Bonds | 2005 Series B due 2035
Debt Instrument [Line Items]
Interest rate	5.625%
Long-Term Debt	$ 100,000	100,000
CL&P | First Mortgage Bonds | 2006 Series A due 2036
Debt Instrument [Line Items]
Interest rate	6.35%
Long-Term Debt	$ 250,000	250,000
CL&P | First Mortgage Bonds | 2007 Series B due 2037
Debt Instrument [Line Items]
Interest rate	5.75%
Long-Term Debt	$ 150,000	150,000
CL&P | First Mortgage Bonds | 2007 Series D due 2037
Debt Instrument [Line Items]
Interest rate	6.375%
Long-Term Debt	$ 100,000	100,000
CL&P | First Mortgage Bonds | 2013 Series A due 2023
Debt Instrument [Line Items]
Interest rate	2.50%
Long-Term Debt	$ 0	400,000
CL&P | First Mortgage Bonds | 2014 Series A due 2044
Debt Instrument [Line Items]
Interest rate	4.30%
Long-Term Debt	$ 475,000	475,000
CL&P | First Mortgage Bonds | 2015 Series A due 2045
Debt Instrument [Line Items]
Interest rate	4.15%
Long-Term Debt	$ 350,000	350,000
CL&P | First Mortgage Bonds | 2017 Series A due 2027
Debt Instrument [Line Items]
Interest rate	3.20%
Long-Term Debt	$ 500,000	500,000
CL&P | First Mortgage Bonds | 2018 Series A due 2048
Debt Instrument [Line Items]
Interest rate	4%
Long-Term Debt	$ 800,000	800,000
CL&P | First Mortgage Bonds | 2020 Series A due 2025
Debt Instrument [Line Items]
Interest rate	0.75%
Long-Term Debt	$ 400,000	400,000
CL&P | First Mortgage Bonds | 2021 Series A due 2031
Debt Instrument [Line Items]
Interest rate	2.05%
Long-Term Debt	$ 425,000	425,000
CL&P | First Mortgage Bonds | 2023 Series A due 2053
Debt Instrument [Line Items]
Interest rate	5.25%
Long-Term Debt	$ 500,000	0
CL&P | First Mortgage Bonds | 2023 Series B due 2033
Debt Instrument [Line Items]
Interest rate	4.90%
Long-Term Debt	$ 300,000	0
CL&P | Commercial Paper
Debt Instrument [Line Items]
Long-Term Debt	139,800	400,000
Current Maturities Classified as Long-Term Debt	207,300	0
NSTAR Electric
Debt Instrument [Line Items]
Long-Term Debt	4,496,947	4,345,085
Less Amounts due Within One Year	0	(80,000)
NSTAR Electric | Unsecured Debt
Debt Instrument [Line Items]
Long-Term Debt	4,400,000	4,250,000
Less Amounts due Within One Year	0	(80,000)
Unamortized Premiums and Discounts, Net	(14,000)	(14,800)
Unamortized Debt Issuance Costs	(29,100)	(30,100)
Long-Term Debt	$ 4,496,900	4,345,100
NSTAR Electric | Unsecured Debt | 2006 Debentures due 2036
Debt Instrument [Line Items]
Interest rate	5.75%
Long-Term Debt	$ 200,000	200,000
NSTAR Electric | Unsecured Debt | 2010 Debentures due 2040
Debt Instrument [Line Items]
Interest rate	5.50%
Long-Term Debt	$ 300,000	300,000
NSTAR Electric | Unsecured Debt | 2014 Debentures due 2044
Debt Instrument [Line Items]
Interest rate	4.40%
Long-Term Debt	$ 300,000	300,000
NSTAR Electric | Unsecured Debt | 2015 Debentures due 2025
Debt Instrument [Line Items]
Interest rate	3.25%
Long-Term Debt	$ 250,000	250,000
NSTAR Electric | Unsecured Debt | 2016 Debentures due 2026
Debt Instrument [Line Items]
Interest rate	2.70%
Long-Term Debt	$ 250,000	250,000
NSTAR Electric | Unsecured Debt | 2017 Debentures due 2027
Debt Instrument [Line Items]
Interest rate	3.20%
Long-Term Debt	$ 700,000	700,000
NSTAR Electric | Unsecured Debt | 2019 Debentures due 2029
Debt Instrument [Line Items]
Interest rate	3.25%
Long-Term Debt	$ 400,000	400,000
NSTAR Electric | Unsecured Debt | 2020 Debentures due 2030
Debt Instrument [Line Items]
Interest rate	3.95%
Long-Term Debt	$ 400,000	400,000
NSTAR Electric | Unsecured Debt | 2021 Debentures due 2051
Debt Instrument [Line Items]
Interest rate	3.10%
Long-Term Debt	$ 300,000	300,000
NSTAR Electric | Unsecured Debt | 2021 Debentures due 2031
Debt Instrument [Line Items]
Interest rate	1.95%
Long-Term Debt	$ 300,000	300,000
NSTAR Electric | Unsecured Debt | 2022 Debentures due 2052
Debt Instrument [Line Items]
Interest rate	4.55%
Long-Term Debt	$ 450,000	450,000
NSTAR Electric | Unsecured Debt | 2022 Debentures due 2052
Debt Instrument [Line Items]
Interest rate	4.95%
Long-Term Debt	$ 400,000	400,000
NSTAR Electric | Unsecured Debt | 2023 Debentures due 2028
Debt Instrument [Line Items]
Interest rate	5.60%
Long-Term Debt	$ 150,000	0
NSTAR Electric | Senior Notes
Debt Instrument [Line Items]
Long-Term Debt	$ 140,000	220,000
NSTAR Electric | Senior Notes | 2004 Senior Notes Series B due 2034
Debt Instrument [Line Items]
Interest rate	5.90%
Long-Term Debt	$ 50,000	50,000
NSTAR Electric | Senior Notes | 2007 Senior Notes Series D due 2037
Debt Instrument [Line Items]
Interest rate	6.70%
Long-Term Debt	$ 40,000	40,000
NSTAR Electric | Senior Notes | 2013 Senior Notes Series G due 2023
Debt Instrument [Line Items]
Interest rate	3.88%
Long-Term Debt	$ 0	80,000
NSTAR Electric | Senior Notes | 2016 Senior Notes Series H due 2026
Debt Instrument [Line Items]
Interest rate	2.75%
Long-Term Debt	$ 50,000	50,000
PSNH
Debt Instrument [Line Items]
Long-Term Debt	1,431,591	1,134,914
Less Amounts due Within One Year	0	(29,668)
PSNH | First Mortgage Bonds
Debt Instrument [Line Items]
Long-Term Debt	1,450,000	1,175,000
Less Amounts due Within One Year	0	(325,000)
Unamortized Premiums and Discounts, Net	(4,900)	(2,500)
Unamortized Debt Issuance Costs	(13,500)	(7,900)
Long-Term Debt	$ 1,431,600	1,134,900
PSNH | First Mortgage Bonds | 2005 Series M due 2035
Debt Instrument [Line Items]
Interest rate	5.60%
Long-Term Debt	$ 50,000	50,000
PSNH | First Mortgage Bonds | 2013 Series S due 2023
Debt Instrument [Line Items]
Interest rate	3.50%
Long-Term Debt	$ 0	325,000
PSNH | First Mortgage Bonds | 2019 Series T due 2049
Debt Instrument [Line Items]
Interest rate	3.60%
Long-Term Debt	$ 300,000	300,000
PSNH | First Mortgage Bonds | 2020 Series U due 2050
Debt Instrument [Line Items]
Interest rate	2.40%
Long-Term Debt	$ 150,000	150,000
PSNH | First Mortgage Bonds | 2021 Series V due 2031
Debt Instrument [Line Items]
Interest rate	2.20%
Long-Term Debt	$ 350,000	350,000
PSNH | First Mortgage Bonds | 2023 Series W due 2053
Debt Instrument [Line Items]
Interest rate	5.15%
Long-Term Debt	$ 300,000	0
PSNH | First Mortgage Bonds | 2023 Series X due 2033
Debt Instrument [Line Items]
Interest rate	5.35%
Long-Term Debt	$ 300,000	0
PSNH | Commercial Paper
Debt Instrument [Line Items]
Long-Term Debt		295,300
Current Maturities Classified as Long-Term Debt	0	295,300
Yankee Gas | First Mortgage Bonds | Yankee Gas - First Mortgage Bonds due 2024 - 2051
Debt Instrument [Line Items]
Long-Term Debt	$ 1,015,000	845,000
Yankee Gas | First Mortgage Bonds | Yankee Gas - First Mortgage Bonds due 2024 - 2051 | Minimum
Debt Instrument [Line Items]
Interest rate	1.38%
Yankee Gas | First Mortgage Bonds | Yankee Gas - First Mortgage Bonds due 2024 - 2051 | Maximum
Debt Instrument [Line Items]
Interest rate	5.51%
NSTAR Gas | First Mortgage Bonds | NSTAR Gas - First Mortgage Bonds due 2025 - 2051
Debt Instrument [Line Items]
Long-Term Debt	$ 705,000	705,000
NSTAR Gas | First Mortgage Bonds | NSTAR Gas - First Mortgage Bonds due 2025 - 2051 | Minimum
Debt Instrument [Line Items]
Interest rate	2.25%
NSTAR Gas | First Mortgage Bonds | NSTAR Gas - First Mortgage Bonds due 2025 - 2051 | Maximum
Debt Instrument [Line Items]
Interest rate	7.11%
EGMA | First Mortgage Bonds | Aquarion - Unsecured Notes due 2028 - 2052
Debt Instrument [Line Items]
Long-Term Debt	$ 708,000	650,000
EGMA | First Mortgage Bonds | Aquarion - Unsecured Notes due 2028 - 2052 | Minimum
Debt Instrument [Line Items]
Interest rate	2.11%
EGMA | First Mortgage Bonds | Aquarion - Unsecured Notes due 2028 - 2052 | Maximum
Debt Instrument [Line Items]
Interest rate	5.73%
Aquarion | Unsecured Debt | Aquarion - Unsecured Notes due 2028 - 2052
Debt Instrument [Line Items]
Long-Term Debt	$ 527,000	464,700
Aquarion | Unsecured Debt | Aquarion - Unsecured Notes due 2028 - 2052 | Minimum
Debt Instrument [Line Items]
Interest rate	3%
Aquarion | Unsecured Debt | Aquarion - Unsecured Notes due 2028 - 2052 | Maximum
Debt Instrument [Line Items]
Interest rate	6.43%
Aquarion | Secured Debt | Aquarion - Secured Debt due 2027 - 2044
Debt Instrument [Line Items]
Long-Term Debt	$ 39,000	34,400
Aquarion | Secured Debt | Aquarion - Secured Debt due 2027 - 2044 | Minimum
Debt Instrument [Line Items]
Interest rate	1.55%
Aquarion | Secured Debt | Aquarion - Secured Debt due 2027 - 2044 | Maximum
Debt Instrument [Line Items]
Interest rate	9.29%
Aquarion | Senior Notes | Aquarion - Senior Notes due 2024
Debt Instrument [Line Items]
Interest rate	4%
Long-Term Debt	$ 360,000	$ 360,000

LONG-TERM DEBT - Narrative (Det

LONG-TERM DEBT - Narrative (Details) - USD ($) $ in Thousands	Feb. 08, 2024	Dec. 31, 2023	Nov. 21, 2023	Jun. 07, 2023	Dec. 31, 2022	Nov. 30, 2022	Jun. 14, 2022
Debt Instrument [Line Items]
Long-term debt		$ 23,588,616			$ 19,723,994
Interest included in payment to settle spent nuclear fuel obligation		9,500			8,800
CL&P
Debt Instrument [Line Items]
Long-term debt		4,814,429			4,216,488
PSNH
Debt Instrument [Line Items]
Long-term debt		1,431,591			1,134,914
NSTAR Electric
Debt Instrument [Line Items]
Long-term debt		4,496,947			4,345,085
Line of Credit | NSTAR Gas
Debt Instrument [Line Items]
Amount of long-term debt requested for issuance							$ 325,000
Line of Credit | CL&P
Debt Instrument [Line Items]
Amount of long-term debt requested for issuance						$ 1,150,000
Line of Credit | PSNH | Subsequent Event
Debt Instrument [Line Items]
Amount of long-term debt requested for issuance	$ 300,000
Line of Credit | Yankee Gas Services Company
Debt Instrument [Line Items]
Amount of long-term debt requested for issuance				$ 350,000
Line of Credit | NSTAR Electric
Debt Instrument [Line Items]
Amount of long-term debt requested for issuance			$ 2,400,000
Pre-1983 Spent Nuclear Fuel Obligation (CYAPC)
Debt Instrument [Line Items]
Long-term debt		$ 12,500			$ 11,900

LONG-TERM DEBT - Schedule of Is

LONG-TERM DEBT - Schedule of Issuances and Repayments (Details) - USD ($) $ in Thousands

1 Months Ended

12 Months Ended

Jan. 31, 2024

Dec. 31, 2023

Nov. 30, 2023

Sep. 30, 2023

Aug. 31, 2023

Jul. 31, 2023

May 31, 2023

Mar. 31, 2023

Jan. 31, 2023

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Debt Instrument [Line Items]

Repayments of debt

$ (2,008,470)

$ (1,175,000)

$ (1,142,500)

NSTAR Electric

Debt Instrument [Line Items]

Repayments of debt

(80,000)

(400,000)

(250,000)

CL&P

Debt Instrument [Line Items]

Repayments of debt

(400,000)

0

(120,500)

PSNH

Debt Instrument [Line Items]

Repayments of debt

(325,000)

0

(282,000)

CL&P 2023 Series A First Mortgage Bonds | First Mortgage Bonds | CL&P

Debt Instrument [Line Items]

Interest rate

5.25%

Issuance

$ 500,000

CL&P 2013 Series A First Mortgage Bonds | First Mortgage Bonds | CL&P

Debt Instrument [Line Items]

Interest rate

2.50%

Repayments of debt

$ (400,000)

CL&P 2023 Series B First Mortgage Bonds | First Mortgage Bonds | CL&P

Debt Instrument [Line Items]

Interest rate

4.90%

Issuance

$ 300,000

CL&P 2024 Series A First Mortgage Bonds | First Mortgage Bonds | CL&P | Subsequent Event

Debt Instrument [Line Items]

Interest rate

4.65%

Issuance

$ 350,000

NSTAR Electric 2023 Debentures | Debentures | NSTAR Electric

Debt Instrument [Line Items]

Interest rate

5.60%

Issuance

$ 150,000

NSTAR Electric 2013 Series G Senior Notes | Senior Notes | NSTAR Electric

Debt Instrument [Line Items]

Interest rate

3.88%

Repayments of debt

$ (80,000)

PSNH Series W First Mortgage Bonds | First Mortgage Bonds | PSNH

Debt Instrument [Line Items]

Interest rate

5.15%

Issuance

$ 300,000

PSNH Series X First Mortgage Bonds | First Mortgage Bonds | PSNH

Debt Instrument [Line Items]

Interest rate

5.35%

Issuance

$ 300,000

PSNH Series S First Mortgage Bonds | First Mortgage Bonds | PSNH

Debt Instrument [Line Items]

Interest rate

3.50%

Repayments of debt

$ (325,000)

Yankee Gas Series V First Mortgage Bonds | First Mortgage Bonds | Yankee Gas Services Company

Debt Instrument [Line Items]

Interest rate

5.51%

Issuance

$ 170,000

EGMA Series D First Mortgage Bonds | First Mortgage Bonds | EGMA

Debt Instrument [Line Items]

Interest rate

5.73%

Issuance

$ 58,000

Aquarion Water Company of Connecticut Senior Notes | Senior Notes | Aquarion Water Company Of Connecticut

Debt Instrument [Line Items]

Interest rate

5.89%

Issuance

$ 50,000

Eversource

Debt Instrument [Line Items]

Repayments of debt

$ (1,200,000)

$ (750,000)

$ (450,000)

Eversource | Eversource Parent Series Z Senior Notes | Senior Notes

Debt Instrument [Line Items]

Interest rate

5.45%

5.45%

Issuance

$ 550,000

$ 750,000

Eversource | Eversource Parent Series F Senior Notes | Senior Notes

Debt Instrument [Line Items]

Interest rate

2.80%

Repayments of debt

$ (450,000)

Eversource | Eversource Parent Series AA Senior Notes | Senior Notes

Debt Instrument [Line Items]

Interest rate

4.75%

Issuance

$ 450,000

Eversource | Eversource Parent Series BB Senior Notes | Senior Notes

Debt Instrument [Line Items]

Interest rate

5.125%

Issuance

$ 800,000

Eversource | Eversource Parent Variable Rate Series T Senior Notes | Senior Notes

Debt Instrument [Line Items]

Repayments of debt

$ (350,000)

Eversource | Eversource Parent Variable Rate Series T Senior Notes | Senior Notes | Secured Overnight Financing Rate (SOFR)

Debt Instrument [Line Items]

Basis spread on compounded SOFR

0.25%

Eversource | Eversource Parent Series CC Senior Notes | Senior Notes

Debt Instrument [Line Items]

Interest rate

5.95%

Issuance

$ 800,000

Eversource | Eversource Parent Series N Senior Notes | Senior Notes

Debt Instrument [Line Items]

Interest rate

3.80%

3.80%

Repayments of debt

$ (400,000)

Eversource | Eversource Parent Series DD Senior Notes | Senior Notes | Subsequent Event

Debt Instrument [Line Items]

Interest rate

5%

Issuance

$ 350,000

Eversource | Eversource Parent Series EE Senior Notes | Senior Notes | Subsequent Event

Debt Instrument [Line Items]

Interest rate

5.50%

Issuance

$ 650,000

LONG-TERM DEBT - Schedule of _2

LONG-TERM DEBT - Schedule of Long-term Debt Maturities (Details) $ in Millions	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
2024	$ 1,950
2025	1,400.2
2026	1,390.2
2027	2,539.2
2028	1,978.5
Thereafter	15,005.7
Total	24,263.8
CL&P
Debt Instrument [Line Items]
2024	139.8
2025	400
2026	0
2027	500
2028	0
Thereafter	3,580
Total	4,619.8
NSTAR Electric
Debt Instrument [Line Items]
2024	0
2025	250
2026	300
2027	700
2028	150
Thereafter	3,140
Total	4,540
PSNH
Debt Instrument [Line Items]
2024	0
2025	0
2026	0
2027	0
2028	0
Thereafter	1,450
Total	$ 1,450

RATE REDUCTION BONDS AND VARI_3

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Narrative (Details) - PSNH - Rate Reduction Bonds $ in Millions	May 31, 2018 USD ($)
Debt Instrument [Line Items]
Amount of securitized rate reduction bonds issued	$ 635.7
Weighted average interest rate (in percent)	3.66%

RATE REDUCTION BONDS AND VARI_4

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	$ 6,389,200	$ 5,578,300
Regulatory Liabilities	4,022,923	3,930,305
Accrued Interest (included in Other Current Liabilities)	1,081,981	989,053
Rate Reduction Bonds - Current Portion	43,210	43,210
Rate Reduction Bonds - Long-Term Portion	$ 367,282	$ 410,492
Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash and Cash Equivalents, Statement of Financial Position [Extensible Enumeration]	Prepayments and Other Current Assets	Prepayments and Other Current Assets
Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	$ 17,300	$ 19,600
Restricted Cash and Cash Equivalents, Statement of Financial Position [Extensible Enumeration]	Other Long-Term Assets	Other Long-Term Assets
Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	$ 392,500	$ 435,700
Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	339,000	322,500
PSNH
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	963,300	696,200
Regulatory Liabilities	393,574	391,628
Accrued Interest (included in Other Current Liabilities)	72,328	59,616
Rate Reduction Bonds - Current Portion	43,210	43,210
Rate Reduction Bonds - Long-Term Portion	367,282	410,492
PSNH | Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	3,200	3,200
PSNH | Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	392,500	435,700
PSNH | Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	8,000	14,400
Variable Interest Entity, Primary Beneficiary | PSNH
Condensed Balance Sheet Statements, Captions [Line Items]
Rate Reduction Bonds - Current Portion	43,200	43,200
Rate Reduction Bonds - Long-Term Portion	367,300	410,500
Variable Interest Entity, Primary Beneficiary | PSNH | Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	30,000	32,400
Variable Interest Entity, Primary Beneficiary | PSNH | Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	3,200	3,200
Variable Interest Entity, Primary Beneficiary | PSNH | Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Cost (included in Regulatory Assets)	392,500	435,700
Variable Interest Entity, Primary Beneficiary | PSNH | Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Liabilities	5,300	6,000
Accrued Interest (included in Other Current Liabilities)	$ 6,300	$ 6,900

RATE REDUCTION BONDS AND VARI_5

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 855,441	$ 678,274	$ 582,334
PSNH
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	72,786	59,548	56,998
Variable Interest Entity, Primary Beneficiary | PSNH | Rate Reduction Bonds
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory (Liabilities)/Assets, Net)	43,200	43,200	43,200
Interest Expense on RRB Principal (included in Interest Expense)	$ 15,700	$ 17,000	$ 18,400

RATE REDUCTION BONDS AND VARI_6

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES- Rate Reduction Bonds, Principal and Interest Payments (Details) - PSNH $ in Millions	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
2024	$ 43.2
2025	43.2
2026	43.2
2027	43.2
2028	43.2
Thereafter	194.5
Total	$ 410.5

EMPLOYEE BENEFITS - Schedule of

EMPLOYEE BENEFITS - Schedule of Pension Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and SERP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	$ (5,220.1)	$ (6,729.7)
Service Cost	(43.1)	(70.1)	$ (85.8)
Interest Cost	(254)	(154.5)	(130)
Actuarial Gain/(Loss)	(110.4)	1,385.8
Benefits Paid	317.3	302.5
Benefits Paid - Lump Sum	28.9	33
Benefits Paid - SERP	43	12.9
Employee Transfers	0	0
Benefit Obligation as of End of Year	(5,238.4)	(5,220.1)	(6,729.7)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	5,806.4	6,495.5
Employer Contributions	5	80
Actual Return on Plan Assets	309.8	(433.6)
Benefits Paid - Pension	(317.3)	(302.5)
Benefits Paid - Lump Sum	(28.9)	(33)
Employee Transfers	0	0
Fair Value of Plan Assets as of End of Year	5,775	5,806.4	6,495.5
Funded Status as of December 31st	536.6	586.3
PBOP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	(693.7)	(884.3)
Service Cost	(7.6)	(11.6)	(13.5)
Interest Cost	(33.8)	(20.2)	(17.4)
Actuarial Gain/(Loss)	5	173.6
Benefits Paid	52.7	52.1
Employee Transfers	0	0
Plan Amendment	1.4	0
Impact of Acquisitions	0	(3.3)
Benefit Obligation as of End of Year	(676)	(693.7)	(884.3)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	970.1	1,138.3
Employer Contributions	1.9	3.1
Actual Return on Plan Assets	104.7	(119.6)
Benefits Paid - Pension	(52.3)	(51.7)
Employee Transfers	0	0
Fair Value of Plan Assets as of End of Year	1,024.4	970.1	1,138.3
Funded Status as of December 31st	348.4	276.4
CL&P | Pension and SERP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	(1,030)	(1,330.9)
Service Cost	(12.3)	(18.7)	(23)
Interest Cost	(50.5)	(31.3)	(27.3)
Actuarial Gain/(Loss)	(19.7)	284.1
Benefits Paid	66.1	63.3
Benefits Paid - Lump Sum	0	0
Benefits Paid - SERP	0.3	0.3
Employee Transfers	(2.4)	3.2
Benefit Obligation as of End of Year	(1,048.5)	(1,030)	(1,330.9)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	1,172	1,323.8
Employer Contributions	0	0
Actual Return on Plan Assets	61.7	(85.3)
Benefits Paid - Pension	(66.1)	(63.3)
Benefits Paid - Lump Sum	0	0
Employee Transfers	2.4	(3.2)
Fair Value of Plan Assets as of End of Year	1,170	1,172	1,323.8
Funded Status as of December 31st	121.5	142
CL&P | PBOP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	(127.9)	(165.5)
Service Cost	(1.3)	(2)	(2.3)
Interest Cost	(6.2)	(3.7)	(3.2)
Actuarial Gain/(Loss)	4.4	33
Benefits Paid	10	10.4
Employee Transfers	0	(0.1)
Plan Amendment	0.4	0
Impact of Acquisitions	0	0
Benefit Obligation as of End of Year	(120.6)	(127.9)	(165.5)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	120.6	145.7
Employer Contributions	0	0
Actual Return on Plan Assets	12.6	(15)
Benefits Paid - Pension	(10)	(10.4)
Employee Transfers	(0.2)	0.3
Fair Value of Plan Assets as of End of Year	123	120.6	145.7
Funded Status as of December 31st	2.4	(7.3)
NSTAR Electric | Pension and SERP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	(1,110.4)	(1,448.4)
Service Cost	(7.8)	(13.8)	(15.8)
Interest Cost	(53.9)	(32.8)	(26.8)
Actuarial Gain/(Loss)	(17.6)	295.5
Benefits Paid	76.7	68.4
Benefits Paid - Lump Sum	5.3	14.8
Benefits Paid - SERP	0.2	0.2
Employee Transfers	0.5	5.7
Benefit Obligation as of End of Year	(1,107)	(1,110.4)	(1,448.4)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	1,418.8	1,596
Employer Contributions	0	15
Actual Return on Plan Assets	75.3	(103.3)
Benefits Paid - Pension	(76.7)	(68.4)
Benefits Paid - Lump Sum	(5.3)	(14.8)
Employee Transfers	(0.5)	(5.7)
Fair Value of Plan Assets as of End of Year	1,411.6	1,418.8	1,596
Funded Status as of December 31st	304.6	308.4
NSTAR Electric | PBOP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	(189.5)	(238.4)
Service Cost	(1.2)	(2)	(2.4)
Interest Cost	(9.2)	(5.3)	(4.4)
Actuarial Gain/(Loss)	(5.8)	39.4
Benefits Paid	16.7	16.6
Employee Transfers	0.5	0.2
Plan Amendment	0.2	0
Impact of Acquisitions	0	0
Benefit Obligation as of End of Year	(188.3)	(189.5)	(238.4)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	456.1	530
Employer Contributions	0	0
Actual Return on Plan Assets	52.3	(57)
Benefits Paid - Pension	(16.7)	(16.6)
Employee Transfers	(1.3)	(0.3)
Fair Value of Plan Assets as of End of Year	490.4	456.1	530
Funded Status as of December 31st	302.1	266.6
PSNH | Pension and SERP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	(556.2)	(721)
Service Cost	(4.3)	(6.9)	(8.9)
Interest Cost	(27.3)	(16.9)	(14.5)
Actuarial Gain/(Loss)	(11.6)	156.7
Benefits Paid	35.7	33.9
Benefits Paid - Lump Sum	1	1
Benefits Paid - SERP	0.4	0.4
Employee Transfers	0	(3.4)
Benefit Obligation as of End of Year	(562.3)	(556.2)	(721)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	618	694.6
Employer Contributions	0	0
Actual Return on Plan Assets	32.7	(45.1)
Benefits Paid - Pension	(35.7)	(33.9)
Benefits Paid - Lump Sum	(1)	(1)
Employee Transfers	0	3.4
Fair Value of Plan Assets as of End of Year	614	618	694.6
Funded Status as of December 31st	51.7	61.8
PSNH | PBOP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation as of Beginning of Year	(74.6)	(92.3)
Service Cost	(0.7)	(1.1)	(1.2)
Interest Cost	(3.7)	(2.2)	(1.8)
Actuarial Gain/(Loss)	0.8	15.2
Benefits Paid	6.1	6
Employee Transfers	(0.1)	(0.2)
Plan Amendment	0.2	0
Impact of Acquisitions	0	0
Benefit Obligation as of End of Year	(72)	(74.6)	(92.3)
Change in Pension Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	72.3	88
Employer Contributions	0	0
Actual Return on Plan Assets	8.3	(9.8)
Benefits Paid - Pension	(6.1)	(6)
Employee Transfers	0.2	0.1
Fair Value of Plan Assets as of End of Year	74.7	72.3	$ 88
Funded Status as of December 31st	$ 2.7	$ (2.3)

EMPLOYEE BENEFITS - Pension Pla

EMPLOYEE BENEFITS - Pension Plan Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Expected long-term rate of return	7.94%	7%
Pension and SERP
Defined Contribution Plan Disclosure [Line Items]
Decrease in liability as a result of a change in discount rate		$ 1,480
Increase of liability as a result of change in discount rate	$ 98.9
Expected long-term rate of return	8.25%	8.25%	8.25%
Employer Contributions	$ 5	$ 80
Estimated future employer contributions in next fiscal year	5
Pension and SERP | CL&P
Defined Contribution Plan Disclosure [Line Items]
Employer Contributions	0	0
Pension and SERP | PSNH
Defined Contribution Plan Disclosure [Line Items]
Employer Contributions	0	0
PBOP
Defined Contribution Plan Disclosure [Line Items]
Decrease in liability as a result of a change in discount rate	17	$ 180.1
Increase of liability as a result of change in discount rate	$ 12
Expected long-term rate of return	8.25%	8.25%	8.25%
Employer Contributions	$ 1.9	$ 3.1
Estimated future employer contributions in next fiscal year	$ 2.4
PBOP | Aquarion
Defined Contribution Plan Disclosure [Line Items]
Expected long-term rate of return	7%	7%
PBOP | CL&P
Defined Contribution Plan Disclosure [Line Items]
Employer Contributions	$ 0	$ 0
PBOP | PSNH
Defined Contribution Plan Disclosure [Line Items]
Employer Contributions	$ 0	$ 0
Pre-65 Plan | PBOP
Defined Contribution Plan Disclosure [Line Items]
Health care trend rate	6.75%
Ultimate rate	5%
Pre-65 Plan | Minimum | PBOP | Aquarion
Defined Contribution Plan Disclosure [Line Items]
Health care trend rate	3.50%	3.50%
Pre-65 Plan | Maximum | PBOP | Aquarion
Defined Contribution Plan Disclosure [Line Items]
Health care trend rate	7%	6.50%
Post-65 Plan | PBOP
Defined Contribution Plan Disclosure [Line Items]
Ultimate rate	3.50%
Eversource Service Pension and PBOP Plans
Defined Contribution Plan Disclosure [Line Items]
Assumed rate of return	8.25%
Aquarion Plans
Defined Contribution Plan Disclosure [Line Items]
Assumed rate of return	7%

EMPLOYEE BENEFITS - Schedule _2

EMPLOYEE BENEFITS - Schedule of Funded Status (Details) - Pension and SERP - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 4,936.8	$ 4,911.6
CL&P
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	977.8	960.7
NSTAR Electric
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	1,051.9	1,055.1
PSNH
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 522.1	$ 516.9

EMPLOYEE BENEFITS - Schedule _3

EMPLOYEE BENEFITS - Schedule of Prepaid Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	$ 1,028.2	$ 1,045.5
Less: Accrued SERP - current portion	(19.4)	(47.3)
Accrued Pension, SERP and PBOP	123.8	135.5
CL&P
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	129.8	147.9
Less: Accrued SERP - current portion	(0.3)	(0.3)
Accrued Pension, SERP and PBOP	5.6	12.9
NSTAR Electric
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	608.6	576.8
Less: Accrued SERP - current portion	(0.2)	(0.2)
Accrued Pension, SERP and PBOP	1.7	1.6
PSNH
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	59	66.4
Less: Accrued SERP - current portion	(0.4)	(0.4)
Accrued Pension, SERP and PBOP	4.2	6.5
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	672.2	756.7
Accrued liability, defined benefit pension plan	0	3.7
Pension Plan | CL&P
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	127.4	147.9
Accrued liability, defined benefit pension plan	0	0
Pension Plan | NSTAR Electric
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	306.5	310.2
Accrued liability, defined benefit pension plan	0	0
Pension Plan | PSNH
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	56.3	66.4
Accrued liability, defined benefit pension plan	0	0
PBOP
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	356	288.8
Accrued liability, defined benefit pension plan	7.6	12.4
PBOP | CL&P
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	2.4	0
Accrued liability, defined benefit pension plan	0	7.3
PBOP | NSTAR Electric
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	302.1	266.6
Accrued liability, defined benefit pension plan	0	0
PBOP | PSNH
Defined Benefit Plan Disclosure [Line Items]
Prepaid asset	2.7	0
Accrued liability, defined benefit pension plan	0	2.3
SERP
Defined Benefit Plan Disclosure [Line Items]
Accrued liability, defined benefit pension plan	135.6	166.7
SERP | CL&P
Defined Benefit Plan Disclosure [Line Items]
Accrued liability, defined benefit pension plan	5.9	5.9
SERP | NSTAR Electric
Defined Benefit Plan Disclosure [Line Items]
Accrued liability, defined benefit pension plan	1.9	1.8
SERP | PSNH
Defined Benefit Plan Disclosure [Line Items]
Accrued liability, defined benefit pension plan	$ 4.6	$ 4.6

EMPLOYEE BENEFITS - Schedule _4

EMPLOYEE BENEFITS - Schedule of Actuarial Assumptions (Details)	Dec. 31, 2023	Dec. 31, 2022
Pension and SERP | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	4.90%	5.10%
Compensation/Progression Rate	3.50%	3.50%
Pension and SERP | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	5%	5.20%
Compensation/Progression Rate	4%	4%
PBOP | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	5%	5.20%
PBOP | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	5.20%

EMPLOYEE BENEFITS - Schedule _5

EMPLOYEE BENEFITS - Schedule of Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and SERP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 43.1	$ 70.1	$ 85.8
Interest Cost	254	154.5	130
Expected Return on Plan Assets	(465)	(523.6)	(437.5)
Actuarial Loss	45.8	116	243.9
Prior Service Cost/(Credit)	1.3	1.4	1.4
Settlement Loss	12.4
Total Net Periodic Benefit Plan Income	(108.4)	$ (181.6)	$ 23.6
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Income, Net	Other Income, Net
PBOP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	7.6	$ 11.6	$ 13.5
Interest Cost	33.8	20.2	17.4
Expected Return on Plan Assets	(77.1)	(89.9)	(79.1)
Actuarial Loss	0	0	8.9
Prior Service Cost/(Credit)	(21.6)	(21.7)	(21.2)
Settlement Loss	0
Total Net Periodic Benefit Plan Income	$ (57.3)	$ (79.8)	$ (60.5)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Income, Net	Other Income, Net	Other Income, Net
CL&P | Pension and SERP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 12.3	$ 18.7	$ 23
Interest Cost	50.5	31.3	27.3
Expected Return on Plan Assets	(94.2)	(106.3)	(86.8)
Actuarial Loss	2.5	16.2	45.5
Prior Service Cost/(Credit)	0	0	0
Settlement Loss	0
Total Net Periodic Benefit Plan Income	(28.9)	(40.1)	9
Intercompany Income Allocations	(4)	(16)	8
CL&P | PBOP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1.3	2	2.3
Interest Cost	6.2	3.7	3.2
Expected Return on Plan Assets	(9.4)	(11.4)	(10.3)
Actuarial Loss	0	0	1.8
Prior Service Cost/(Credit)	1.1	1.1	1.1
Settlement Loss	0
Total Net Periodic Benefit Plan Income	(0.8)	(4.6)	(1.9)
Intercompany Income Allocations	(1.9)	(3.7)	(1.6)
NSTAR Electric | Pension and SERP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	7.8	13.8	15.8
Interest Cost	53.9	32.8	26.8
Expected Return on Plan Assets	(113.8)	(128.4)	(108.1)
Actuarial Loss	17.1	32.8	61.6
Prior Service Cost/(Credit)	0.3	0.3	0.3
Settlement Loss	0
Total Net Periodic Benefit Plan Income	(34.7)	(48.7)	(3.6)
Intercompany Income Allocations	(3)	(12.4)	8.8
NSTAR Electric | PBOP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1.2	2	2.4
Interest Cost	9.2	5.3	4.4
Expected Return on Plan Assets	(36.9)	(42.4)	(36.9)
Actuarial Loss	0	0	2.4
Prior Service Cost/(Credit)	(17)	(17)	(17)
Settlement Loss	0
Total Net Periodic Benefit Plan Income	(43.5)	(52.1)	(44.7)
Intercompany Income Allocations	(2.1)	(3.6)	(1.9)
PSNH | Pension and SERP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	4.3	6.9	8.9
Interest Cost	27.3	16.9	14.5
Expected Return on Plan Assets	(49.5)	(56.1)	(47.5)
Actuarial Loss	1.5	7.9	20.7
Prior Service Cost/(Credit)	0	0	0
Settlement Loss	0
Total Net Periodic Benefit Plan Income	(16.4)	(24.4)	(3.4)
Intercompany Income Allocations	(0.8)	(3.6)	2.7
PSNH | PBOP
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.7	1.1	1.2
Interest Cost	3.7	2.2	1.8
Expected Return on Plan Assets	(5.5)	(6.7)	(6.1)
Actuarial Loss	0	0	0.7
Prior Service Cost/(Credit)	0.4	0.4	0.4
Settlement Loss	0
Total Net Periodic Benefit Plan Income	(0.7)	(3)	(2)
Intercompany Income Allocations	$ (0.7)	$ (1.2)	$ (0.6)

EMPLOYEE BENEFITS - Schedule _6

EMPLOYEE BENEFITS - Schedule of Assumptions used To Calculate Pension and SERP and PBOP (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Expected Long-Term Rate of Return (in percent)	7.94%	7%
Pension and SERP
Defined Benefit Plan Disclosure [Line Items]
Expected Long-Term Rate of Return (in percent)	8.25%	8.25%	8.25%
PBOP
Defined Benefit Plan Disclosure [Line Items]
Expected Long-Term Rate of Return (in percent)	8.25%	8.25%	8.25%
Minimum | Pension and SERP
Defined Benefit Plan Disclosure [Line Items]
Discount rate (in percent)	4.90%	2.20%	1.50%
Compensation/Progression Rate (in percent)	3.50%	3.50%	3.50%
Minimum | PBOP
Defined Benefit Plan Disclosure [Line Items]
Discount rate (in percent)	5.10%	2.30%	1.80%
Maximum | Pension and SERP
Defined Benefit Plan Disclosure [Line Items]
Discount rate (in percent)	5.30%	3.20%	3%
Compensation/Progression Rate (in percent)	4%	4%	4%
Maximum | PBOP
Defined Benefit Plan Disclosure [Line Items]
Discount rate (in percent)	5.40%	3.30%	3.10%

EMPLOYEE BENEFITS - Summary of

EMPLOYEE BENEFITS - Summary of Changes in Plan Assets and Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pension and SERP
Net Regulatory Assets [Abstract]
Actuarial (Gain)/Loss Arising During the Year	$ 251.1	$ (431.6)
Actuarial Loss Reclassified as Net Periodic Benefit Expense	(38.8)	(107)
Settlement Loss	0	0
Prior Service Credit Arising During the Year	0	0
Prior Service (Cost)/Credit Reclassified as Net Periodic Benefit (Expense)/Income	(1.2)	(1.2)
Actuarial Loss	1,101	888.7
Prior Service (Credit)/Cost	2.9	4.1
OCI
Actuarial (Gain)/Loss Arising During the Year	14	4.6
Actuarial Loss Reclassified as Net Periodic Benefit Expense	(7)	(9)
Settlement Loss	(12.4)	0
Prior Service Credit Arising During the Year	0	0
Prior Service (Cost)/Credit Reclassified as Net Periodic Benefit (Expense)/Income	(0.1)	(0.2)
Actuarial Loss	56.5	61.9
Prior Service Cost	0.3	0.4
PBOP
Net Regulatory Assets [Abstract]
Actuarial (Gain)/Loss Arising During the Year	(32)	36.8
Actuarial Loss Reclassified as Net Periodic Benefit Expense	0	0
Settlement Loss	0	0
Prior Service Credit Arising During the Year	(0.9)	0
Prior Service (Cost)/Credit Reclassified as Net Periodic Benefit (Expense)/Income	21.8	21.8
Actuarial Loss	49.8	81.8
Prior Service (Credit)/Cost	(87.4)	(108.3)
OCI
Actuarial (Gain)/Loss Arising During the Year	(0.3)	(0.8)
Actuarial Loss Reclassified as Net Periodic Benefit Expense	0	0
Settlement Loss	0	0
Prior Service Credit Arising During the Year	0	0
Prior Service (Cost)/Credit Reclassified as Net Periodic Benefit (Expense)/Income	(0.2)	(0.1)
Actuarial Loss	2.4	2.7
Prior Service Cost	$ 0.7	$ 0.9

EMPLOYEE BENEFITS - Schedule _7

EMPLOYEE BENEFITS - Schedule of Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2023 USD ($)
Pension and SERP
Defined Contribution Plan Disclosure [Line Items]
2024	$ 370.2
2025	367.1
2026	370.8
2027	373.8
2028	375
2029 - 2033	1,864.3
PBOP
Defined Contribution Plan Disclosure [Line Items]
2024	55.2
2025	54.7
2026	53.8
2027	52.8
2028	51.8
2029 - 2033	$ 241.1

EMPLOYEE BENEFITS - Schedule _8

EMPLOYEE BENEFITS - Schedule of Long-term Rates of Return on Pension and PBOP (Details)	Dec. 31, 2023	Dec. 31, 2022
United States
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		15%
Assumed Rate of Return (in percent)	8.50%	8.50%
United States | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	0%
United States | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	20%
Global
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		10%
Assumed Rate of Return (in percent)	8.75%	8.75%
Global | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	20%
Global | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	0%
Non-United States
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		8%
Assumed Rate of Return (in percent)	8.50%	8.50%
Non-United States | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	0%
Non-United States | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	11%
Emerging Markets
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		4%
Assumed Rate of Return (in percent)	10%	10%
Emerging Markets | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	0%
Emerging Markets | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	6%
Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		13%
Assumed Rate of Return (in percent)	5.50%	4%
Fixed Income | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	16%
Fixed Income | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	17%
Public High Yield Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		4%
Assumed Rate of Return (in percent)	7.50%	6.50%
Public High Yield Fixed Income | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	5%
Public High Yield Fixed Income | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	0%
United States Treasuries
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		0%
Assumed Rate of Return (in percent)	4.50%	0%
United States Treasuries | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	11%
United States Treasuries | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	0%
Private Debt
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		13%
Assumed Rate of Return (in percent)	10%	9%
Private Debt | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	10%
Private Debt | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	13%
Private Equity
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		18%
Assumed Rate of Return (in percent)	12%	12%
Private Equity | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	23%
Private Equity | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	18%
Real Assets
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)		15%
Assumed Rate of Return (in percent)	7.50%	7.50%
Real Assets | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	15%
Real Assets | PBOP
Defined Contribution Plan Disclosure [Line Items]
Target Asset Allocation (in percent)	15%

EMPLOYEE BENEFITS - Schedule _9

EMPLOYEE BENEFITS - Schedule of Asset Category (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and SERP
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 5,775	$ 5,806.4	$ 6,495.5
Uncategorized	4,776.8	5,116.9
Pension and SERP | Total Assets Before 401
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	6,019.9	6,062
Pension and SERP | Equity Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	1,227	1,509.9
Uncategorized	853	1,102.2
Pension and SERP | Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	2,211.9	1,954.4
Uncategorized	1,516.4	1,598.8
Pension and SERP | Private Equity
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	1,685.3	1,684.9
Uncategorized	1,685.3	1,684.9
Pension and SERP | Real Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	895.7	912.8
Uncategorized	722.1	731
Pension and SERP | 401 PBOP Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	(244.9)	(255.6)
Pension and SERP | Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	902.2	866.6
Pension and SERP | Level 1 | Equity Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	374	407.7
Pension and SERP | Level 1 | Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	354.6	277.1
Pending redemption settlements	31	138
Pension and SERP | Level 1 | Private Equity
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Pension and SERP | Level 1 | Real Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	173.6	181.8
Pension and SERP | Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	340.9	78.5
Pension and SERP | Level 2 | Equity Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Pension and SERP | Level 2 | Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	340.9	78.5
Pension and SERP | Level 2 | Private Equity
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Pension and SERP | Level 2 | Real Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
PBOP
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	1,024.4	970.1	$ 1,138.3
Uncategorized	493.5	431.7
PBOP | Total Assets Before 401
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	779.5	714.5
PBOP | Equity Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	351.2	336.7
Uncategorized	212.1	183.5
PBOP | Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	236.2	199.5
Uncategorized	159.8	141.1
PBOP | Private Equity
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	87.7	70.9
Uncategorized	87.7	70.9
PBOP | Real Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	104.4	107.4
Uncategorized	33.9	36.2
PBOP | 401 PBOP Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	244.9	255.6
PBOP | Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	243	242.6
PBOP | Level 1 | Equity Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	139.1	153.2
PBOP | Level 1 | Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	33.4	18.2
PBOP | Level 1 | Private Equity
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
PBOP | Level 1 | Real Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	70.5	71.2
PBOP | Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	43	40.2
PBOP | Level 2 | Equity Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
PBOP | Level 2 | Fixed Income
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	43	40.2
PBOP | Level 2 | Private Equity
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
PBOP | Level 2 | Real Assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 0	$ 0

EMPLOYEE BENEFITS - Defined Con

EMPLOYEE BENEFITS - Defined Contribution Plan Narrative (Details)	12 Months Ended
	Dec. 31, 2023
Defined Contribution Plan, 401K
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution (as a percentage)	100%
Percentage of employees' pay (up to)	3%
Defined Contribution Plan, Alternate Contribution 401K
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution (as a percentage)	50%
Percentage of employees' pay (up to)	8%

EMPLOYEE BENEFITS - Schedule_10

EMPLOYEE BENEFITS - Schedule of Defined Contribution Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, cost recognized	$ 67.3	$ 59.9	$ 55.5
CL&P
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, cost recognized	9	7.7	7
NSTAR Electric
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, cost recognized	13.7	12.8	12.2
PSNH
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, cost recognized	$ 5.4	$ 4.8	$ 4.3

EMPLOYEE BENEFITS - Share-Based

EMPLOYEE BENEFITS - Share-Based Payments Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in incentive plan (up to) (in shares)	7,400,000
Shares available for issuance under incentive plan (in shares)	4,587,376	903,183
Shares outstanding (in shares)	326,581
Weighted average grant date fair value of restricted stock units (in dollars per share)	$ 86.92
Total unrecognized compensation expense	$ 31.3
Period for recognition	1 year 9 months 21 days
Tax effect on total share-based payments (in percentage)	26%
Excess stock benefit	$ (0.5)	$ 2.1	$ 4
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	$ 76.42	$ 85.96	$ 81.89
Shares outstanding (in shares)		300,592
Weighted average shares outstanding (in dollars per share)	$ 80.76	$ 87.21
Restricted stock units available (in shares)	199,145
Restricted stock unit fully vested (in shares)	345,661
Additional restricted stock unit expected to vest (in shares)	310,252
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	$ 83.39	$ 83.34	$ 76.08
Shares outstanding (in shares)	485,480	457,069
Weighted average shares outstanding (in dollars per share)	$ 85.20	$ 88.43
Restricted stock units available (in shares)	214,742
Weighted average grant date fair value of restricted stock units (in dollars per share)	$ 89.70
Restricted stock unit fully vested (in shares)	178,944
CL&P
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation expense	$ 5.8
Excess stock benefit	(0.2)	$ 0.7	$ 1.5
NSTAR Electric
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation expense	8.6
Excess stock benefit	(0.2)	0.8	1.4
PSNH
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation expense	1.9
Excess stock benefit	$ (0.1)	$ 0.3	$ 0.5
Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of graded vesting schedule under long-term incentive program	3 years
Board Members
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of graded vesting schedule under long-term incentive program	1 year

EMPLOYEE BENEFITS - Summary o_2

EMPLOYEE BENEFITS - Summary of RSU and Share Transactions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted Stock Units (RSUs)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance (in shares)	629,734
Granted (in shares)	248,124
Shares issued (in shares)	(181,409)
Forfeited (in shares)	(24,207)
Ending balance (in shares)	672,242	629,734
Weighted Average Grant-Date Fair Value
Beginning balance (in dollars per share)	$ 68.52
Granted (in dollars per share)	76.42	$ 85.96	$ 81.89
Shares issued (in dollars per share)	87.09
Forfeited (in dollars per share)	83.43
Ending balance (in dollars per share)	$ 65.89	$ 68.52
Performance Shares
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance (in shares)	547,290
Granted (in shares)	278,983
Shares issued (in shares)	(125,677)
Forfeited (in shares)	(36,172)
Ending balance (in shares)	664,424	547,290
Weighted Average Grant-Date Fair Value
Beginning balance (in dollars per share)	$ 87.49
Granted (in dollars per share)	83.39	$ 83.34	$ 76.08
Shares issued (in dollars per share)	90.49
Forfeited (in dollars per share)	85.13
Ending balance (in dollars per share)	$ 85.33	$ 87.49

EMPLOYEE BENEFITS - Schedule_11

EMPLOYEE BENEFITS - Schedule of Compensation Expense and Income Tax Benefit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense	$ 27.8	$ 33.4	$ 28.2
Future Income Tax Benefit	7.3	8.7	7.3
CL&P
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense	8.7	10	8.8
Future Income Tax Benefit	2.3	2.6	2.3
NSTAR Electric
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense	8.7	10.7	9
Future Income Tax Benefit	2.3	2.8	2.3
PSNH
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense	3	3.6	3
Future Income Tax Benefit	$ 0.8	$ 0.9	$ 0.8

EMPLOYEE BENEFITS - Schedule_12

EMPLOYEE BENEFITS - Schedule of Other Retirement Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actuarially-Determined Liability	$ 32.6	$ 43.4	$ 42.8
Other Retirement Benefits Expense	2.6	10.9	2.2
Retirement benefit payable	9.2
CL&P
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actuarially-Determined Liability	0.2	0.2	0.2
Other Retirement Benefits Expense	0.8	4	0.7
NSTAR Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actuarially-Determined Liability	0	0.1	0.1
Other Retirement Benefits Expense	0.8	3.7	0.7
PSNH
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actuarially-Determined Liability	1.1	1.3	1.5
Other Retirement Benefits Expense	$ 0.4	$ 1.3	$ 0.3

INCOME TAXES - Components of In

INCOME TAXES - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current Income Taxes:
Federal	$ 75,800	$ 95,800	$ 21,500
State	600	13,600	(21,600)
Total Current	76,400	109,400	(100)
Deferred Income Taxes, Net:
Federal	(900)	198,800	199,700
State	86,300	148,000	147,400
Total Deferred	85,405	346,779	347,056
Investment Tax Credits, Net	(2,100)	(2,600)	(2,800)
Income Tax Expense	159,684	453,574	344,223
CL&P
Current Income Taxes:
Federal	(10,800)	106,200	15,000
State	(2,300)	20,100	(7,000)
Total Current	(13,100)	126,300	8,000
Deferred Income Taxes, Net:
Federal	130,300	17,200	76,300
State	53,700	28,200	47,600
Total Deferred	184,037	45,381	123,889
Investment Tax Credits, Net	0	(500)	(600)
Income Tax Expense	170,909	171,198	131,273
NSTAR Electric
Current Income Taxes:
Federal	50,700	55,000	52,300
State	7,800	8,700	6,200
Total Current	58,500	63,700	58,500
Deferred Income Taxes, Net:
Federal	50,100	35,600	16,300
State	46,100	42,400	41,200
Total Deferred	96,224	78,039	57,507
Investment Tax Credits, Net	(1,700)	(1,700)	(1,700)
Income Tax Expense	152,996	139,977	114,335
PSNH
Current Income Taxes:
Federal	(40,000)	29,600	43,100
State	(20,000)	5,900	10,800
Total Current	(60,000)	35,500	53,900
Deferred Income Taxes, Net:
Federal	81,200	5,900	(14,900)
State	37,800	9,900	400
Total Deferred	118,970	15,765	(14,530)
Investment Tax Credits, Net	0	0	0
Income Tax Expense	$ 59,014	$ 51,314	$ 39,433

INCOME TAXES - Reconciliation B

INCOME TAXES - Reconciliation Between Income Tax Expense and Expected Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Contingency [Line Items]
(Loss)/Income Before Income Tax Benefit	$ (275,037)	$ 1,865,968	$ 1,572,269
Statutory Federal Income Tax Expense at 21%	(57,700)	391,900	330,200
Tax Effect of Differences:
Depreciation	(25,800)	(17,100)	(18,100)
Investment Tax Credit Amortization	(2,100)	(2,600)	(2,800)
State Income Taxes, Net of Federal Impact	(11,400)	75,900	54,400
Dividends on ESOP	(5,300)	(5,100)	(5,100)
Tax Asset Valuation   Allowance/Reserve Adjustments	295,800	51,600	44,600
Tax Deficiency/(Excess Stock Benefit)	500	(2,100)	(4,000)
EDIT Amortization	(51,500)	(49,100)	(69,100)
Other, Net	17,200	10,200	14,100
Income Tax Expense	$ 159,684	$ 453,574	$ 344,223
Effective Tax Rate	(58.10%)	24.30%	21.90%
CL&P
Income Tax Contingency [Line Items]
(Loss)/Income Before Income Tax Benefit	$ 689,642	$ 704,118	$ 532,998
Statutory Federal Income Tax Expense at 21%	144,900	147,900	111,900
Tax Effect of Differences:
Depreciation	(5,600)	(3,700)	(6,400)
Investment Tax Credit Amortization	0	(500)	(600)
State Income Taxes, Net of Federal Impact	(10,700)	(6,600)	(4,600)
Tax Asset Valuation   Allowance/Reserve Adjustments	51,300	44,700	36,700
Tax Deficiency/(Excess Stock Benefit)	200	(700)	(1,500)
EDIT Amortization	(10,500)	(9,200)	(9,800)
Other, Net	1,300	(700)	5,600
Income Tax Expense	$ 170,909	$ 171,198	$ 131,273
Effective Tax Rate	24.80%	24.30%	24.60%
NSTAR Electric
Income Tax Contingency [Line Items]
(Loss)/Income Before Income Tax Benefit	$ 697,524	$ 632,405	$ 590,904
Statutory Federal Income Tax Expense at 21%	146,500	132,800	124,100
Tax Effect of Differences:
Depreciation	(8,800)	(4,200)	(3,400)
Investment Tax Credit Amortization	(1,700)	(1,700)	(1,700)
State Income Taxes, Net of Federal Impact	42,500	40,300	37,500
Tax Asset Valuation   Allowance/Reserve Adjustments	0	0	0
Tax Deficiency/(Excess Stock Benefit)	200	(800)	(1,400)
EDIT Amortization	(28,400)	(29,200)	(43,200)
Other, Net	2,700	2,800	2,400
Income Tax Expense	$ 152,996	$ 139,977	$ 114,335
Effective Tax Rate	21.90%	22.10%	19.30%
PSNH
Income Tax Contingency [Line Items]
(Loss)/Income Before Income Tax Benefit	$ 254,673	$ 222,884	$ 189,771
Statutory Federal Income Tax Expense at 21%	53,500	46,800	39,900
Tax Effect of Differences:
Depreciation	(1,000)	900	(200)
Investment Tax Credit Amortization	0	0	0
State Income Taxes, Net of Federal Impact	14,100	12,500	8,900
Tax Asset Valuation   Allowance/Reserve Adjustments	0	0	0
Tax Deficiency/(Excess Stock Benefit)	100	(300)	(500)
EDIT Amortization	(6,800)	(7,700)	(10,500)
Other, Net	(900)	(900)	1,800
Income Tax Expense	$ 59,014	$ 51,314	$ 39,433
Effective Tax Rate	23.20%	23%	20.80%

INCOME TAXES - Temporary Differ

INCOME TAXES - Temporary Differences That Give Rise To Accumulated Deferred Income Tax Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred Tax Assets:
Employee Benefits	$ 244.5	$ 228.9
Derivative Liabilities	33	53.8
Regulatory Deferrals - Liabilities	452	529.5
Allowance for Uncollectible Accounts	143.8	125.5
Tax Effect - Tax Regulatory Liabilities	739	762.9
Net Operating Loss Carryforwards	13.8	16.7
Purchase Accounting Adjustment	56.7	62
Equity Method Wind Investments	584.9	0
Other	200.1	176.6
Total Deferred Tax Assets	2,467.8	1,955.9
Less: Valuation Allowance	328.1	82.8
Net Deferred Tax Assets	2,139.7	1,873.1
Deferred Tax Liabilities:
Accelerated Depreciation and Other   Plant-Related Differences	5,103.3	4,793.7
Property Tax Accruals	95	95.3
Regulatory Amounts:
Regulatory Deferrals - Assets	1,512.3	1,251.9
Tax Effect - Tax Regulatory Assets	284	271.7
Goodwill-related Regulatory Asset - 1999 Merger	72.2	76.8
Employee Benefits	282	305.5
Derivative Assets	6.4	10.5
Other	88.2	135.6
Total Deferred Tax Liabilities	7,443.4	6,941
Offshore Wind Business
Regulatory Amounts:
Impairment charge	224
CL&P
Deferred Tax Assets:
Employee Benefits	29.9	25.3
Derivative Liabilities	33	53.8
Regulatory Deferrals - Liabilities	94.4	146.6
Allowance for Uncollectible Accounts	79.6	60.5
Tax Effect - Tax Regulatory Liabilities	320.7	324.6
Net Operating Loss Carryforwards	0	0
Purchase Accounting Adjustment	0	0
Equity Method Wind Investments	0	0
Other	125.3	109.5
Total Deferred Tax Assets	682.9	720.3
Less: Valuation Allowance	80.6	63.3
Net Deferred Tax Assets	602.3	657
Deferred Tax Liabilities:
Accelerated Depreciation and Other   Plant-Related Differences	1,703.4	1,602
Property Tax Accruals	42	40.7
Regulatory Amounts:
Regulatory Deferrals - Assets	470	406.4
Tax Effect - Tax Regulatory Assets	191.9	185.6
Goodwill-related Regulatory Asset - 1999 Merger	0	0
Employee Benefits	38.8	45
Derivative Assets	6.4	10.5
Other	9.9	6.8
Total Deferred Tax Liabilities	2,462.4	2,297
NSTAR Electric
Deferred Tax Assets:
Employee Benefits	66.8	57.4
Derivative Liabilities	0	0
Regulatory Deferrals - Liabilities	291.5	285.7
Allowance for Uncollectible Accounts	21.5	20.7
Tax Effect - Tax Regulatory Liabilities	227.1	241.8
Net Operating Loss Carryforwards	0	0
Purchase Accounting Adjustment	0	0
Equity Method Wind Investments	0	0
Other	25	20.5
Total Deferred Tax Assets	631.9	626.1
Less: Valuation Allowance	0	0
Net Deferred Tax Assets	631.9	626.1
Deferred Tax Liabilities:
Accelerated Depreciation and Other   Plant-Related Differences	1,728.6	1,643.7
Property Tax Accruals	39.8	41.3
Regulatory Amounts:
Regulatory Deferrals - Assets	474.5	407.9
Tax Effect - Tax Regulatory Assets	10.5	10.7
Goodwill-related Regulatory Asset - 1999 Merger	61.9	65.9
Employee Benefits	146.7	140.8
Derivative Assets	0	0
Other	19.5	16.7
Total Deferred Tax Liabilities	2,481.5	2,327
PSNH
Deferred Tax Assets:
Employee Benefits	13	11.6
Derivative Liabilities	0	0
Regulatory Deferrals - Liabilities	23.8	42.1
Allowance for Uncollectible Accounts	3.9	7.9
Tax Effect - Tax Regulatory Liabilities	95.5	97.8
Net Operating Loss Carryforwards	0	0
Purchase Accounting Adjustment	0	0
Equity Method Wind Investments	0	0
Other	23.4	21.3
Total Deferred Tax Assets	159.6	180.7
Less: Valuation Allowance	0	0
Net Deferred Tax Assets	159.6	180.7
Deferred Tax Liabilities:
Accelerated Depreciation and Other   Plant-Related Differences	566.5	523.8
Property Tax Accruals	6.3	6.7
Regulatory Amounts:
Regulatory Deferrals - Assets	250.3	165.2
Tax Effect - Tax Regulatory Assets	8.3	7.9
Goodwill-related Regulatory Asset - 1999 Merger	0	0
Employee Benefits	16.8	18.7
Derivative Assets	0	0
Other	2.9	21.2
Total Deferred Tax Liabilities	$ 851.1	$ 743.5

INCOME TAXES - Tax Credits and

INCOME TAXES - Tax Credits and Loss Carryforwards (Details) - State and Local Jurisdiction - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
State Net Operating Loss	$ 243.4	$ 288.1
State Tax Credit	228.5	204.5
State Charitable Contribution	7.9	20.1
CL&P
Operating Loss Carryforwards [Line Items]
State Net Operating Loss	0	0
State Tax Credit	157.5	137.7
State Charitable Contribution	0	0
NSTAR Electric
Operating Loss Carryforwards [Line Items]
State Net Operating Loss	0	0
State Tax Credit	0	0
State Charitable Contribution	0	0
PSNH
Operating Loss Carryforwards [Line Items]
State Net Operating Loss	0	0
State Tax Credit	0	0
State Charitable Contribution	$ 0	$ 0

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Interest expense on uncertain tax positions	$ 300,000	$ 0	$ 0
Accrued interest payable	400,000	100,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Valuation allowance for tax credit and operating loss carryforward	104,100,000	82,800,000
State and Local Jurisdiction | CL&P
Operating Loss Carryforwards [Line Items]
Change in valuation allowance	17,300,000	18,800,000
Eversource | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Change in valuation allowance	$ 21,300,000	$ 21,300,000

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of Unrecognized Tax Benefit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 67.1	$ 65.8	$ 61.8
Gross Increases - Current Year	23.4	11.5	11.3
Gross Increases - Prior Year	0.1
Gross Decreases - Prior Year	(0.1)	(2.4)	(0.3)
Lapse of Statute of Limitations	(9.2)	(7.8)	(7)
Ending Balance	81.3	67.1	65.8
CL&P
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	25.5	26.2	25.8
Gross Increases - Current Year	4	3.5	3.8
Gross Increases - Prior Year	0.1
Gross Decreases - Prior Year	0	(0.9)	(0.6)
Lapse of Statute of Limitations	(3.8)	(3.3)	(2.8)
Ending Balance	$ 25.8	$ 25.5	$ 26.2

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Schedule of Reconciliation of Activity in Environmental Reserve (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrual for Environmental Loss Contingencies, Beginning Balance	$ 122.6	$ 115.4
Additions	16.8	12.6
Payments/Reductions	(11.2)	(5.4)
Accrual for Environmental Loss Contingencies, Ending Balance	$ 128.2	$ 122.6
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities	Other Current Liabilities
CL&P
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrual for Environmental Loss Contingencies, Beginning Balance	$ 13.9	$ 13.9
Additions	2.6	0.9
Payments/Reductions	(2.7)	(0.9)
Accrual for Environmental Loss Contingencies, Ending Balance	13.8	13.9
NSTAR Electric
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrual for Environmental Loss Contingencies, Beginning Balance	3.4	3.3
Additions	2.5	0.4
Payments/Reductions	(0.5)	(0.3)
Accrual for Environmental Loss Contingencies, Ending Balance	5.4	3.4
PSNH
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrual for Environmental Loss Contingencies, Beginning Balance	6.1	6.3
Additions	1.7	0.5
Payments/Reductions	(0.2)	(0.7)
Accrual for Environmental Loss Contingencies, Ending Balance	$ 7.6	$ 6.1

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Schedule of Number of Sites and Reserves (Details) - site	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Number of Sites	65	59
CL&P
Loss Contingencies [Line Items]
Number of Sites	16	13
NSTAR Electric
Loss Contingencies [Line Items]
Number of Sites	12	10
PSNH
Loss Contingencies [Line Items]
Number of Sites	8	8

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Environmental Matters Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) site	Dec. 31, 2022 USD ($) site	Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items]
Number of sites | site	65	59
Reserve | $	$ 128.2	$ 122.6	$ 115.4
CL&P
Loss Contingencies [Line Items]
Number of additional sites | site	3
Number of sites | site	16	13
Reserve | $	$ 13.8	$ 13.9	13.9
NSTAR Electric
Loss Contingencies [Line Items]
Number of additional sites | site	2
Number of sites | site	12	10
Reserve | $	$ 5.4	$ 3.4	3.3
PSNH
Loss Contingencies [Line Items]
Number of sites | site	8	8
Reserve | $	$ 7.6	$ 6.1	$ 6.3
NSTAR Gas
Loss Contingencies [Line Items]
Number of additional sites | site	1
MGP Site accrual
Loss Contingencies [Line Items]
Reserve balances related to former MGP sites | $	$ 117.1	$ 112.6
Environmental Sites for Which a Range of Loss Exists
Loss Contingencies [Line Items]
Number of sites | site	7
Reserve | $	$ 29.4
Best estimate of potential remediation costs (up to) | $	$ 17.7
Environmental Sites for Which a Range of Loss Exists | CL&P
Loss Contingencies [Line Items]
Number of sites | site	1
Reserve | $	$ 0.4
Best estimate of potential remediation costs (up to) | $	$ 0.5
Environmental Site for Which a Range is Too Early to Determine
Loss Contingencies [Line Items]
Number of sites | site	19
Reserve | $	$ 39.9
Environmental Site for Which a Range is Too Early to Determine | CL&P
Loss Contingencies [Line Items]
Number of sites | site	11
Reserve | $	$ 12.6
Environmental Site for Which a Range is Too Early to Determine | NSTAR Electric
Loss Contingencies [Line Items]
Number of sites | site	1
Reserve | $	$ 0.3
Evironmental Sites with Best Estimate
Loss Contingencies [Line Items]
Number of sites | site	39
Reserve | $	$ 58.9
Evironmental Sites with Best Estimate | CL&P
Loss Contingencies [Line Items]
Reserve | $	$ 0.8
Environmental site quantity remaining | site	4
Evironmental Sites with Best Estimate | NSTAR Electric
Loss Contingencies [Line Items]
Reserve | $	$ 5.1
Environmental site quantity remaining | site	11
Evironmental Sites with Best Estimate | PSNH
Loss Contingencies [Line Items]
Reserve | $	$ 7.6
Environmental site quantity remaining | site	8

COMMITMENTS AND CONTINGENCIES_4

COMMITMENTS AND CONTINGENCIES - Schedule of Estimated Future Annual Costs of Long term Contractual Agreement (Details) $ in Millions	Dec. 31, 2023 USD ($)
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	$ 1,315.8
2025	1,376.8
2026	1,228.8
2027	1,205.3
2028	1,169.7
Thereafter	6,659.9
Total	12,956.3
Renewable Energy Purchase Contracts
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	769.4
2025	863
2026	867.9
2027	897.6
2028	893.1
Thereafter	5,368.8
Total	9,659.8
Natural Gas Procurement
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	423.2
2025	402.3
2026	317.8
2027	264.8
2028	236
Thereafter	1,211.8
Total	2,855.9
Purchased Power and Capacity
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	86.7
2025	75.2
2026	2.9
2027	2.7
2028	2.7
Thereafter	4.5
Total	174.7
Peaker CfDs
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	17.2
2025	14.1
2026	12.8
2027	9.1
2028	6.8
Thereafter	43.7
Total	103.7
Transmission Support Commitments
Transmission Support Commitments
2024	19.3
2025	22.2
2026	27.4
2027	31.1
2028	31.1
Thereafter	31.1
Total	162.2
CL&P
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	727.4
2025	723.6
2026	651.7
2027	652.6
2028	651.3
Thereafter	2,143.8
Total	5,550.4
CL&P | Renewable Energy Purchase Contracts
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	618.8
2025	628.3
2026	628
2027	631.2
2028	632.2
Thereafter	2,087.8
Total	5,226.3
CL&P | Purchased Power and Capacity
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	83.8
2025	72.4
2026	0.1
2027	0
2028	0
Thereafter	0
Total	156.3
CL&P | Peaker CfDs
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	17.2
2025	14.1
2026	12.8
2027	9.1
2028	6.8
Thereafter	43.7
Total	103.7
CL&P | Transmission Support Commitments
Transmission Support Commitments
2024	7.6
2025	8.8
2026	10.8
2027	12.3
2028	12.3
Thereafter	12.3
Total	64.1
NSTAR Electric
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	133.5
2025	214.4
2026	220.1
2027	224.3
2028	220.1
Thereafter	3,000.3
Total	4,012.7
NSTAR Electric | Renewable Energy Purchase Contracts
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	123
2025	202.9
2026	206.5
2027	209.3
2028	205.1
Thereafter	2,983.5
Total	3,930.3
NSTAR Electric | Purchased Power and Capacity
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	2.9
2025	2.8
2026	2.8
2027	2.7
2028	2.7
Thereafter	4.5
Total	18.4
NSTAR Electric | Transmission Support Commitments
Transmission Support Commitments
2024	7.6
2025	8.7
2026	10.8
2027	12.3
2028	12.3
Thereafter	12.3
Total	64
PSNH
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	31.7
2025	36.5
2026	39.2
2027	63.6
2028	62.3
Thereafter	304
Total	537.3
PSNH | Renewable Energy Purchase Contracts
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	27.6
2025	31.8
2026	33.4
2027	57.1
2028	55.8
Thereafter	297.5
Total	503.2
PSNH | Transmission Support Commitments
Transmission Support Commitments
2024	4.1
2025	4.7
2026	5.8
2027	6.5
2028	6.5
Thereafter	6.5
Total	$ 34.1

COMMITMENTS AND CONTINGENCIES_5

COMMITMENTS AND CONTINGENCIES - Long-Term Contractual Arrangement Narrative (Details) MWh in Millions, $ in Millions				12 Months Ended
	Nov. 22, 2019	Mar. 15, 2019	Dec. 28, 2018 MWh	Dec. 31, 2023 USD ($) MW contract
Long-term Purchase Commitment [Line Items]
Estimated cost of energy purchase contracts				$ 12,956.3
Peaker Contracts For Differences
Long-term Purchase Commitment [Line Items]
Estimated cost of energy purchase contracts				$ 103.7
Percentage of costs and benefits borne by United Illuminated Company				20%
Period of payment to generation facility owner				30 years
CL&P
Long-term Purchase Commitment [Line Items]
Estimated cost of energy purchase contracts				$ 5,550.4
CL&P | Peaker Contracts For Differences
Long-term Purchase Commitment [Line Items]
Estimated cost of energy purchase contracts				$ 103.7
Number of capacity contracts | contract				3
Amount of peaking capacity contracts (in MW) | MW				500
Percentage of costs and benefits borne				80%
CL&P, NSTAR Electric and PSNH | Transmission Support Commitments
Long-term Purchase Commitment [Line Items]
Period of payment of annual operation and maintenance expense				20 years
NSTAR Electric
Long-term Purchase Commitment [Line Items]
Contract term (in years)				20 years
Estimated cost of energy purchase contracts				$ 4,012.7
NSTAR Electric | Construction in Progress
Long-term Purchase Commitment [Line Items]
Total construction contract cost				2,600
NSTAR Electric | Minimum
Long-term Purchase Commitment [Line Items]
Estimated costs under construction contract				100
NSTAR Electric | Maximum
Long-term Purchase Commitment [Line Items]
Estimated costs under construction contract				200
Millstone Nuclear Power Station and Seabrook Nuclear Power Plant
Long-term Purchase Commitment [Line Items]
Estimated cost of energy purchase contracts				$ 2,400
Milestone Nuclear Power Station
Long-term Purchase Commitment [Line Items]
Annual purchase requirement (in MWh) | MWh			9
Percent of the facility's output required to be purchased		50%
Milestone Nuclear Power Station | CL&P
Long-term Purchase Commitment [Line Items]
Contract term (in years)			10 years
Percent of the facility's output required to be purchased		40%
Milestone Nuclear Power Station | UI
Long-term Purchase Commitment [Line Items]
Contract term (in years)			10 years
Seabrook Nuclear Power Plant
Long-term Purchase Commitment [Line Items]
Percent of the facility's output required to be purchased	18%
Seabrook Nuclear Power Plant | CL&P
Long-term Purchase Commitment [Line Items]
Contract term (in years)			8 years
Percent of the facility's output required to be purchased	15%
Seabrook Nuclear Power Plant | UI
Long-term Purchase Commitment [Line Items]
Contract term (in years)			8 years
Vineyard Wind Project | NSTAR Electric
Long-term Purchase Commitment [Line Items]
Contract term (in years)				20 years
Nameplate capacity (in MW) | MW				800

COMMITMENTS AND CONTINGENCIES_6

COMMITMENTS AND CONTINGENCIES - Schedule of Total Costs Incurred (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Long-term Purchase Commitment [Line Items]
Renewable Energy Purchase Contracts	$ 581.4	$ 678.1	$ 609.2
Natural Gas Procurement	695.8	1,042.8	712.7
Purchased Power and Capacity	69	61.6	56.4
Peaker CfDs	20.1	13.4	24.3
Transmission Support Commitments	14.2	12.7	15.4
CL&P
Long-term Purchase Commitment [Line Items]
Renewable Energy Purchase Contracts	474.1	513.2	457.1
Purchased Power and Capacity	65.5	57.7	53.1
Peaker CfDs	20.1	13.4	24.3
Transmission Support Commitments	5.6	5	6.1
NSTAR Electric
Long-term Purchase Commitment [Line Items]
Renewable Energy Purchase Contracts	60	90.8	84.7
Purchased Power and Capacity	2.9	3	3
Peaker CfDs	0	0	0
Transmission Support Commitments	5.6	5	6
PSNH
Long-term Purchase Commitment [Line Items]
Renewable Energy Purchase Contracts	47.3	74.1	67.4
Purchased Power and Capacity	0.6	0.9	0.3
Peaker CfDs	0	0	0
Transmission Support Commitments	$ 3	$ 2.7	$ 3.3

COMMITMENTS AND CONTINGENCIES_7

COMMITMENTS AND CONTINGENCIES - Spent Nuclear Fuel Obligations Narrative (Details) - USD ($) $ in Millions	Jun. 08, 2022	Mar. 25, 2021
Yankee Companies
Guarantor Obligations [Line Items]
Damages sought	$ 33.1	$ 120.4

COMMITMENTS AND CONTINGENCIES_8

COMMITMENTS AND CONTINGENCIES - Guarantees and Obligations Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Fair value of guarantees	$ 4.4	$ 4.2

COMMITMENTS AND CONTINGENCIES_9

COMMITMENTS AND CONTINGENCIES - Schedule of Guarantees and Indemnifications (Details) $ in Millions	1 Months Ended
	Jan. 31, 2024 USD ($) letterOfCredit	Jan. 24, 2024	Jan. 01, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Guarantor Obligations [Line Items]
Maximum exposure guarantee				$ 4.4	$ 4.2
Eversource Investment LLC | Letter of Credit
Guarantor Obligations [Line Items]
Maximum Exposure				15.2
Amount of long-term debt requested for issuance				$ 25
Eversource Investment LLC | Letter of Credit | Subsequent Event
Guarantor Obligations [Line Items]
Maximum Exposure	$ 8
Letters of credit issued | letterOfCredit	2
North East Offshore, Sunrise Wind LLC, Revolution Wind, LLC and South Fork Wind, LLC
Guarantor Obligations [Line Items]
Ownership interest (in percent)				50%
Sunrise Wind LLC | Subsequent Event
Guarantor Obligations [Line Items]
Ownership interest (in percent)		50%
South Fork Wind, LLC
Guarantor Obligations [Line Items]
Maximum Exposure				$ 7.1
Ownership interest (in percent)				50%
Eversource Investment LLC and South Fork Class B Member, LLC
Guarantor Obligations [Line Items]
Maximum Exposure				$ 1,520
South Fork Class B Member, LLC
Guarantor Obligations [Line Items]
Ownership interest (in percent)				50%
OREC Capacity Production | Sunrise Wind LLC
Guarantor Obligations [Line Items]
Maximum Exposure				$ 15.4
Ownership interest (in percent)				50%
Maximum exposure guarantee				$ 11
OREC Capacity Production | Sunrise Wind LLC | Subsequent Event
Guarantor Obligations [Line Items]
Maximum exposure guarantee			$ 15.4
Surety Bonds | Sunrise Wind LLC
Guarantor Obligations [Line Items]
Maximum Exposure				20.5
Tax Equity | Eversource TEI LLC
Guarantor Obligations [Line Items]
Maximum Exposure				528.4
North East Offshore, Sunrise Wind LLC, Revolution Wind, LLC and South Fork Wind, LLC | Offshore wind construction-related purchase agreements with third-party contractors
Guarantor Obligations [Line Items]
Maximum Exposure				1,941.1
North East Offshore, Sunrise Wind LLC, Revolution Wind, LLC and South Fork Wind, LLC | Performance Guarantee
Guarantor Obligations [Line Items]
Maximum Exposure				3,030
Eversource Investment LLC and South Fork Class B Member, LLC | Funding and Indemnification Obligations
Guarantor Obligations [Line Items]
Maximum Exposure				485.9
Sunrise Wind LLC | OREC Capacity Production
Guarantor Obligations [Line Items]
Maximum Exposure				11
Sunrise Wind LLC | Surety Bonds
Guarantor Obligations [Line Items]
Maximum Exposure				20.5
South Fork Wind, LLC | Power Purchase Agreement Security
Guarantor Obligations [Line Items]
Maximum Exposure				7.1
Eversource Investment LLC | Letters of Credit
Guarantor Obligations [Line Items]
Maximum Exposure				15.2
Eversource TEI LLC | South Fork Wind Tax Equity
Guarantor Obligations [Line Items]
Maximum Exposure				0
Various | Surety Bonds
Guarantor Obligations [Line Items]
Maximum Exposure				38.8
North East Offshore LLC | Payment Guarantee
Guarantor Obligations [Line Items]
Maximum Exposure				$ 62.5
Percent of obligations guaranteed				50%

COMMITMENTS AND CONTINGENCIE_10

COMMITMENTS AND CONTINGENCIES - FERC ROE Complaints Narrative (Details) $ in Millions			12 Months Ended	30 Months Ended	36 Months Ended
	Oct. 16, 2018 complaint	Apr. 29, 2016 complaint	Dec. 31, 2023 USD ($)	Apr. 14, 2017	Oct. 15, 2014	Dec. 31, 2022 USD ($)	Jul. 31, 2014 complaint
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified	10.41%
Percentage of incentive cap on total ROE	13.08%
FERC ROE Complaints
Loss Contingencies [Line Items]
Loss contingency, pending claims, number | complaint	4	4
Period of complaint			15 months
Basis point change			0.10%
Estimate of possible loss for each 10 basis point change to base ROE			$ 3
Complaint period			15 months
FERC ROE First, Second and Third Complaints
Loss Contingencies [Line Items]
Loss contingency, pending claims, number | complaint							3
Base ROE percentage challenged by complainants			11.14%
Percentage of ROE for any incentive project	13.08%
FERC ROE First Complaint
Loss Contingencies [Line Items]
Percentage of ROE for any incentive project				11.74%
Refund payments			$ 38.9
FERC ROE Second Complaint
Loss Contingencies [Line Items]
Percentage of base ROE of complaint period			10.57%	10.57%
Percentage of ROE for any incentive project			11.74%
Loss contingency, estimate of possible earnings impact			$ 39.1
FERC ROE Fourth Complaint
Loss Contingencies [Line Items]
Percentage of base ROE of complaint period		10.57%
Maximum percentage cap of ROE for incentive projects		11.74%
Percentage of ROE for any incentive project			10.57%
Original base ROE authorized by FERC at time of complaint			11.74%
FERC MISO Complaints
Loss Contingencies [Line Items]
Loss contingency, pending claims, number | complaint	2
CL&P | FERC ROE First Complaint
Loss Contingencies [Line Items]
Refund payments			$ 22.4
CL&P | FERC ROE Second Complaint
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			21.4			$ 21.4
NSTAR Electric | FERC ROE First Complaint
Loss Contingencies [Line Items]
Refund payments			13.7
NSTAR Electric | FERC ROE Second Complaint
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			14.6			14.6
PSNH | FERC ROE First Complaint
Loss Contingencies [Line Items]
Refund payments			2.8
PSNH | FERC ROE Second Complaint
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			$ 3.1			$ 3.1
Minimum | FERC ROE First, Second and Third Complaints
Loss Contingencies [Line Items]
Percentage of ROE for any incentive project					11.14%
Maximum | FERC ROE First, Second and Third Complaints
Loss Contingencies [Line Items]
Percentage of ROE for any incentive project					13.10%

COMMITMENTS AND CONTINGENCIE_11

COMMITMENTS AND CONTINGENCIES - CL&P Tropical Storm Isaias Response Investigation (Details) $ in Millions	Jul. 14, 2021 USD ($)	May 07, 2021	Apr. 28, 2021
Loss Contingencies [Line Items]
Loss contingency, allowed rate of ROE, downward adjustment			0.0090
Loss contingency, allowed rate of ROE (in percent)			9.25%
Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Non-compliance fine	$ 28.6
Loss contingency, accident reporting violation fines	$ 0.2
Loss contingency, penalty rate as a percent of distribution revenues		2.50%

COMMITMENTS AND CONTINGENCIE_12

COMMITMENTS AND CONTINGENCIES - CL&P Comprehensive Settlement Agreement (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Oct. 01, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2022	Oct. 27, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Bill of forgiveness		$ 166,418	$ 521,752	$ 221,008			$ 264,950
Regulatory Liabilities		591,750	890,786
Loss related to litigation settlement		0	(72,041)	81,274
Basis points reduction to return on equity, scenario one	0.90%
Basis points reduction to return on equity, scenario two	0.45%
CL&P
Loss Contingencies [Line Items]
Bill of forgiveness		12,243	20,327	74,788			$ 99,809
Regulatory Liabilities		102,239	336,048
Loss related to litigation settlement		$ 0	(72,041)	81,274
CL&P | Customer Assistance Fund
Loss Contingencies [Line Items]
Bill of forgiveness					$ 10,000
Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Loss related to litigation settlement				103,600
Customer credits and assistance	$ 75,000
Loss related to litigation settlement, net of tax				$ 86,100
Loss contingency, after-tax earnings impact per share (in dollars per share)				$ 0.25
Unfavorable Regulatory Action | Sales
Loss Contingencies [Line Items]
Loss related to litigation settlement				$ 65,000
Unfavorable Regulatory Action | Oil and Gas, Operation and Maintenance
Loss Contingencies [Line Items]
Loss related to litigation settlement				10,000
Unfavorable Regulatory Action | CL&P
Loss Contingencies [Line Items]
Customer credits						$ 65,000
Customer assistance initiatives						$ 10,000
Regulatory Liabilities				75,000
Unfavorable Regulatory Action | CL&P | Sales
Loss Contingencies [Line Items]
Loss related to litigation settlement				$ 65,000
Unfavorable Regulatory Action | CL&P | Oil and Gas, Operation and Maintenance
Loss Contingencies [Line Items]
Loss related to litigation settlement			$ 10,000

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Lessee, Lease, Description [Line Items]
Lease agreements executed but not yet commenced	$ 11.5
Decrease in right of use asset	$ 7.5
Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
CL&P
Lessee, Lease, Description [Line Items]
Lease agreements executed but not yet commenced	$ 7
CL&P | Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
CL&P | Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
NSTAR Electric
Lessee, Lease, Description [Line Items]
Lease agreements executed but not yet commenced	$ 4.5
NSTAR Electric | Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
NSTAR Electric | Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
PSNH | Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
PSNH | Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years

LEASES - Components of Lease Co

LEASES - Components of Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lease, Cost [Abstract]
Amortization of Right-of-use-Assets	$ 4.8	$ 8.3	$ 4.6
Interest on Lease Liabilities	2	2	3.9
Total Finance Lease Cost	6.8	10.3	8.5
Operating Lease Cost	11.4	11.6	12.2
Variable Lease Cost	69.2	78.1	61
Total Lease Cost	87.4	100	81.7
CL&P
Lease, Cost [Abstract]
Amortization of Right-of-use-Assets	0	0	0.5
Interest on Lease Liabilities	0	0	0.1
Total Finance Lease Cost	0	0	0.6
Operating Lease Cost	0.7	0.3	0.3
Variable Lease Cost	21.9	25.6	16.2
Total Lease Cost	22.6	25.9	17.1
NSTAR Electric
Lease, Cost [Abstract]
Amortization of Right-of-use-Assets	0.2	0.2	0.2
Interest on Lease Liabilities	0.6	0.6	0.6
Total Finance Lease Cost	0.8	0.8	0.8
Operating Lease Cost	3	2.3	2.3
Variable Lease Cost	0	0	0
Total Lease Cost	3.8	3.1	3.1
PSNH
Lease, Cost [Abstract]
Amortization of Right-of-use-Assets	0	0.1	0.1
Interest on Lease Liabilities	0	0	0
Total Finance Lease Cost	0	0.1	0.1
Operating Lease Cost	0.4	0.1	0.1
Variable Lease Cost	47.3	52.5	44.8
Total Lease Cost	$ 47.7	$ 52.7	$ 45

LEASES - Supplemental Balance S

LEASES - Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating Leases:
Right-of-use-Assets, Net	$ 53.5	$ 56.9
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other Long-Term Assets	Other Long-Term Assets
Current Portion	$ 9.5	$ 9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Long-Term	$ 44	$ 47.9
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Long-Term Liabilities	Other Long-Term Liabilities
Total Operating Lease Liabilities	$ 53.5	$ 56.9
Finance Leases:
Right-of-use-Assets, Net	$ 68.6	$ 54.5
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property, Plant and Equipment, Net	Property, Plant and Equipment, Net
Current Portion	$ 5.4	$ 3.8
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Long-Term	$ 67.3	$ 54.2
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Long-Term Liabilities	Other Long-Term Liabilities
Total Finance Lease Liabilities	$ 72.7	$ 58
CL&P
Operating Leases:
Right-of-use-Assets, Net	2.2	2.2
Current Portion	0.8	0.6
Long-Term	1.4	1.6
Total Operating Lease Liabilities	2.2	2.2
Finance Leases:
Right-of-use-Assets, Net	18.3	0
Current Portion	1.4	0
Long-Term	16.9	0
Total Finance Lease Liabilities	18.3	0
NSTAR Electric
Operating Leases:
Right-of-use-Assets, Net	27.7	22.5
Current Portion	2.2	1.2
Long-Term	25.5	21.3
Total Operating Lease Liabilities	27.7	22.5
Finance Leases:
Right-of-use-Assets, Net	3	3.2
Current Portion	0	0
Long-Term	4.9	4.9
Total Finance Lease Liabilities	4.9	4.9
PSNH
Operating Leases:
Right-of-use-Assets, Net	4.7	0
Current Portion	1.5	0
Long-Term	3.2	0
Total Operating Lease Liabilities	4.7	0
Finance Leases:
Right-of-use-Assets, Net	0	0
Current Portion	0	0
Long-Term	0	0
Total Finance Lease Liabilities	$ 0	$ 0

LEASES - Other Information Rela

LEASES - Other Information Related to Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Weighted-Average Remaining Lease Term (Years):
Operating Leases	9 years	11 years
Finance Leases	13 years	15 years
Weighted-Average Discount Rate (Percentage):
Operating Leases	4%	3.20%
Finance Leases	3.30%	2.70%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 10.5	$ 11.3	$ 12.1
Operating Cash Flows from Finance Leases	2	2	3.4
Financing Cash Flows from Finance Leases	3.9	3.9	4.1
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	12.8	18.9	2.1
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 18.5	$ 3.5	2.3
CL&P
Weighted-Average Remaining Lease Term (Years):
Operating Leases	4 years	4 years
Finance Leases	9 years
Weighted-Average Discount Rate (Percentage):
Operating Leases	5.20%	3.80%
Finance Leases	5.30%	0%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0.7	$ 0.3	0.3
Operating Cash Flows from Finance Leases	0	0	0.1
Financing Cash Flows from Finance Leases	0	0	1.4
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.6	2.4	0
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 18.3	$ 0	0
NSTAR Electric
Weighted-Average Remaining Lease Term (Years):
Operating Leases	13 years	17 years
Finance Leases	18 years	19 years
Weighted-Average Discount Rate (Percentage):
Operating Leases	4.20%	4%
Finance Leases	2.90%	2.90%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 2.5	$ 2.1	2.1
Operating Cash Flows from Finance Leases	0.6	0.6	0.6
Financing Cash Flows from Finance Leases	0	0	0
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	7	0	1.9
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0	$ 0	0
PSNH
Weighted-Average Remaining Lease Term (Years):
Operating Leases	3 years
Weighted-Average Discount Rate (Percentage):
Operating Leases	5.20%	0%
Finance Leases	0%	0%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0.4	$ 0.1	0.1
Operating Cash Flows from Finance Leases	0	0	0
Financing Cash Flows from Finance Leases	0	0.1	0.1
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	5	0	0
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0	$ 0	$ 0

LEASES - Future Minimum Lease P

LEASES - Future Minimum Lease Payments under Long-Term Leases (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating Leases
2024	$ 11.1
2025	8.3
2026	6.9
2027	4.3
2028	4.3
Thereafter	30.3
Future lease payments	65.2
Less amount representing interest	11.7
Present value of future minimum lease payments	53.5	$ 56.9
Finance Leases
2024	7.8
2025	8.2
2026	7.8
2027	7.9
2028	7.2
Thereafter	57.8
Future lease payments	96.7
Less amount representing interest	24
Present value of future minimum lease payments	72.7	58
CL&P
Operating Leases
2024	0.9
2025	0.9
2026	0.5
2027	0
2028	0
Thereafter	0
Future lease payments	2.3
Less amount representing interest	0.1
Present value of future minimum lease payments	2.2	2.2
Finance Leases
2024	1.9
2025	2.3
2026	2.4
2027	2.5
2028	2.6
Thereafter	11.5
Future lease payments	23.2
Less amount representing interest	4.9
Present value of future minimum lease payments	18.3	0
NSTAR Electric
Operating Leases
2024	3.4
2025	3
2026	3
2027	2.3
2028	2.4
Thereafter	24.6
Future lease payments	38.7
Less amount representing interest	11
Present value of future minimum lease payments	27.7	22.5
Finance Leases
2024	0.6
2025	0.7
2026	0.7
2027	0.7
2028	0.7
Thereafter	11
Future lease payments	14.4
Less amount representing interest	9.5
Present value of future minimum lease payments	4.9	4.9
PSNH
Operating Leases
2024	1.7
2025	1.7
2026	1.5
2027	0.1
2028	0
Thereafter	0
Future lease payments	5
Less amount representing interest	0.3
Present value of future minimum lease payments	4.7	0
Finance Leases
Present value of future minimum lease payments	$ 0	$ 0

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	$ 155,569	$ 155,570
Rate Reduction Bonds	367,282	410,492
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	24,413,500	21,044,100
Rate Reduction Bonds	410,500	453,700
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	122,200	136,700
Long-Term Debt	22,855,200	18,891,300
Rate Reduction Bonds	395,000	424,700
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	4,814,400	4,216,500
Rate Reduction Bonds	0	0
CL&P | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	90,400	99,200
Long-Term Debt	4,572,000	3,828,300
CL&P | Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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	4,496,900	4,425,100
Rate Reduction Bonds	0	0
NSTAR Electric | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	31,800	37,500
Long-Term Debt	4,273,700	4,091,800
NSTAR Electric | Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate Reduction Bonds	0	0
PSNH
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate Reduction Bonds	367,282	410,492
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	1,431,600	1,164,600
Rate Reduction Bonds	410,500	453,700
PSNH | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	0	0
Long-Term Debt	1,292,600	970,500
Rate Reduction Bonds	$ 395,000	$ 424,700

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Schedule of Changes in AOCI By Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 15,473,158	$ 14,599,844	$ 14,063,566
OCI Before Reclassifications	(8,800)	(4,100)
Amounts Reclassified from AOCI	14,500	7,000
Other Comprehensive Income/(Loss), Net of Tax	5,700	2,900
Ending balance	14,173,892	15,473,158	14,599,844
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(39,421)	(42,275)	(76,411)
Ending balance	(33,737)	(39,421)	(42,275)
Qualified Cash Flow Hedging Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(400)	(400)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	0	0
Other Comprehensive Income/(Loss), Net of Tax	0	0
Ending balance	(400)	(400)	(400)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(1,200)	400
OCI Before Reclassifications	0	(1,600)
Amounts Reclassified from AOCI	1,200	0
Other Comprehensive Income/(Loss), Net of Tax	1,200	(1,600)
Ending balance	0	(1,200)	400
Defined Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(37,800)	(42,300)
OCI Before Reclassifications	(8,800)	(2,500)
Amounts Reclassified from AOCI	13,300	7,000
Other Comprehensive Income/(Loss), Net of Tax	4,500	4,500
Ending balance	$ (33,300)	$ (37,800)	$ (42,300)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity [Abstract]
Related tax effect recognized in AOCI	$ 4.9	$ 1.3	$ 8.3

ACCUMULATED OTHER COMPREHENSI_5

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Schedule of Amounts Reclassified From AOCI By Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Income, Net	$ 348,069	$ 346,088	$ 161,282
Tax Effect	(159,684)	(453,574)	(344,223)
Net (Loss)/Income Attributable to Common Shareholders	(442,240)	1,404,875	1,220,527
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (Loss)/Income Attributable to Common Shareholders	(14,500)	(7,000)	(10,700)
Qualified Cash Flow Hedging Instruments, Net of Tax | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense	0	0	(1,700)
Tax Effect	0	0	700
Net (Loss)/Income Attributable to Common Shareholders	0	0	(1,000)
Unrealized Gains/(Losses) on Marketable Securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Income, Net	(1,600)	0	0
Tax Effect	400	0	0
Net (Loss)/Income Attributable to Common Shareholders	(1,200)	0	0
Defined Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total pre-tax amount	(19,700)	(9,300)	(13,100)
Tax Effect	6,400	2,300	3,400
Net (Loss)/Income Attributable to Common Shareholders	(13,300)	(7,000)	(9,700)
Amortization of Actuarial Losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Income, Net	(7,000)	(9,000)	(13,100)
Amortization of Prior Service Cost | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Income, Net	(300)	(300)	0
Settlement Loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Income, Net	$ (12,400)	$ 0	$ 0

DIVIDEND RESTRICTIONS (Details)

DIVIDEND RESTRICTIONS (Details) $ in Millions	Dec. 31, 2023 USD ($)
Schedule of Restrictions on Retained Earnings [Line Items]
Consolidated total debt to total capital ratio (as a percentage)	0.70
Retained earnings subject to restrictions	$ 4,140
CL&P
Schedule of Restrictions on Retained Earnings [Line Items]
Consolidated total debt to total capital ratio (as a percentage)	0.65
Retained earnings subject to restrictions	$ 2,650
NSTAR Electric
Schedule of Restrictions on Retained Earnings [Line Items]
Retained earnings subject to restrictions	$ 3,140
PSNH
Schedule of Restrictions on Retained Earnings [Line Items]
Consolidated total debt to total capital ratio (as a percentage)	0.65
Retained earnings subject to restrictions	$ 655.8
Yankee Gas
Schedule of Restrictions on Retained Earnings [Line Items]
Consolidated total debt to total capital ratio (as a percentage)	0.65
EGMA
Schedule of Restrictions on Retained Earnings [Line Items]
Consolidated total debt to total capital ratio (as a percentage)	0.65
Aquarion Water Company
Schedule of Restrictions on Retained Earnings [Line Items]
Consolidated total debt to total capital ratio (as a percentage)	0.65
NSTAR Gas
Schedule of Restrictions on Retained Earnings [Line Items]
Consolidated total debt to total capital ratio (as a percentage)	0.65

COMMON SHARES - Common Shares A

COMMON SHARES - Common Shares Authorized and Issued (Details) - $ / shares	Dec. 31, 2023	May 03, 2023	May 02, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Per share par value (in dollars per share)	$ 5			$ 5
Authorized (in shares)	410,000,000	410,000,000	380,000,000	380,000,000
Issued (in shares)	359,984,073			359,984,073
CL&P
Class of Stock [Line Items]
Per share par value (in dollars per share)	$ 10			$ 10
Authorized (in shares)	24,500,000			24,500,000
Issued (in shares)	6,035,205			6,035,205
NSTAR Electric
Class of Stock [Line Items]
Per share par value (in dollars per share)	$ 1			$ 1
Authorized (in shares)	100,000,000			100,000,000
Issued (in shares)	200			200
PSNH
Class of Stock [Line Items]
Per share par value (in dollars per share)	$ 1			$ 1
Authorized (in shares)	100,000,000			100,000,000
Issued (in shares)	301			301

COMMON SHARES - Narrative (Deta

COMMON SHARES - Narrative (Details) - USD ($) $ in Thousands				12 Months Ended
	Oct. 03, 2022	May 11, 2022	Dec. 01, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	May 03, 2023	May 02, 2023	Dec. 31, 2020
Class of Stock [Line Items]
Maximum amount of stock to be issued		$ 1,200,000
Equity offering (in shares)				0	2,165,671
Consideration received from sale of stock					$ 197,100
Treasury stock, common (in shares)				10,443,807	11,540,218
Common stock outstanding (in shares)				349,540,266	348,443,855
Issuance of treasury shares for acquisition			$ 38,100		$ 72,133	$ 38,051
Authorized (in shares)				410,000,000	380,000,000		410,000,000	380,000,000
Subsidiaries | The Torrington Water Company (TWC)
Class of Stock [Line Items]
Purchase price	$ 72,100
Common Shares
Class of Stock [Line Items]
Common stock outstanding (in shares)				349,540,266	348,443,855	344,403,196			342,954,023
Issuance of treasury shares for acquisition (in shares)	925,264		462,517		925,264	462,517

PREFERRED STOCK NOT SUBJECT T_3

PREFERRED STOCK NOT SUBJECT TO MANDATORY REDEMPTION - Narrative (Details)	Dec. 31, 2023 $ / shares shares
CL&P
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares) | shares	9,000,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 50
NSTAR Electric
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares) | shares	2,890,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 100

PREFERRED STOCK NOT SUBJECT T_4

PREFERRED STOCK NOT SUBJECT TO MANDATORY REDEMPTION - Schedule of Preferred Stock by Class (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Preferred stock value outstanding	$ 155.6	$ 155.6
CL&P
Class of Stock [Line Items]
Shares outstanding (in shares)	2,324,000	2,324,000
Preferred stock value outstanding	$ 116.2	$ 116.2
CL&P | Series of 1947 Preferred Stock at $1.90
Class of Stock [Line Items]
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)	$ 1,900,000	$ 1,900,000
Redemption Price Per Share (in dollars per share)	$ 52.50
Shares outstanding (in shares)	163,912	163,912
Preferred stock value outstanding	$ 8.2	$ 8.2
CL&P | Series of 1947 Preferred Stock at $2.00
Class of Stock [Line Items]
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)	$ 2,000,000	$ 2,000,000
Redemption Price Per Share (in dollars per share)	$ 54
Shares outstanding (in shares)	336,088	336,088
Preferred stock value outstanding	$ 16.8	$ 16.8
CL&P | Series of 1949 Preferred Stock at $2.04
Class of Stock [Line Items]
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)	$ 2,040,000	$ 2,040,000
Redemption Price Per Share (in dollars per share)	$ 52
Shares outstanding (in shares)	100,000	100,000
Preferred stock value outstanding	$ 5	$ 5
CL&P | Series of 1949 Preferred Stock at $2.20
Class of Stock [Line Items]
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)	$ 2,200,000	$ 2,200,000
Redemption Price Per Share (in dollars per share)	$ 52.50
Shares outstanding (in shares)	200,000	200,000
Preferred stock value outstanding	$ 10	$ 10
CL&P | Series of 1949 Preferred Stock at 3.90%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	3.90%	3.90%
Redemption Price Per Share (in dollars per share)	$ 50.50
Shares outstanding (in shares)	160,000	160,000
Preferred stock value outstanding	$ 8	$ 8
CL&P | Series E of 1954 Preferred Stock at $2.06
Class of Stock [Line Items]
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)	$ 2,060,000	$ 2,060,000
Redemption Price Per Share (in dollars per share)	$ 51
Shares outstanding (in shares)	200,000	200,000
Preferred stock value outstanding	$ 10	$ 10
CL&P | Series F of 1955 Preferred Stock at $2.09
Class of Stock [Line Items]
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)	$ 2,090,000	$ 2,090,000
Redemption Price Per Share (in dollars per share)	$ 51
Shares outstanding (in shares)	100,000	100,000
Preferred stock value outstanding	$ 5	$ 5
CL&P | Series of 1956 Preferred Stock at 4.5%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	4.50%	4.50%
Redemption Price Per Share (in dollars per share)	$ 50.75
Shares outstanding (in shares)	104,000	104,000
Preferred stock value outstanding	$ 5.2	$ 5.2
CL&P | Series of 1958 Preferred Stock at 4.96%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	4.96%	4.96%
Redemption Price Per Share (in dollars per share)	$ 50.50
Shares outstanding (in shares)	100,000	100,000
Preferred stock value outstanding	$ 5	$ 5
CL&P | Series of 1963 Preferred Stock at 4.5%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	4.50%	4.50%
Redemption Price Per Share (in dollars per share)	$ 50.50
Shares outstanding (in shares)	160,000	160,000
Preferred stock value outstanding	$ 8	$ 8
CL&P | Series of 1967 Preferred Stock at 5.28%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	5.28%	5.28%
Redemption Price Per Share (in dollars per share)	$ 51.43
Shares outstanding (in shares)	200,000	200,000
Preferred stock value outstanding	$ 10	$ 10
CL&P | Series G of 1968 Preferred Stock at $3.24
Class of Stock [Line Items]
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)	$ 3,240,000	$ 3,240,000
Redemption Price Per Share (in dollars per share)	$ 51.84
Shares outstanding (in shares)	300,000	300,000
Preferred stock value outstanding	$ 15	$ 15
CL&P | Series of 1968 Preferred Stock at 6.56%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	6.56%	6.56%
Redemption Price Per Share (in dollars per share)	$ 51.44
Shares outstanding (in shares)	200,000	200,000
Preferred stock value outstanding	$ 10	$ 10
NSTAR Electric
Class of Stock [Line Items]
Shares outstanding (in shares)	430,000	430,000
Preferred stock value outstanding	$ 43	$ 43
NSTAR Electric | Preferred Stock 4.25%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	4.25%	4.25%
Redemption Price Per Share (in dollars per share)	$ 103.625
Shares outstanding (in shares)	180,000	180,000
Preferred stock value outstanding	$ 18	$ 18
NSTAR Electric | Preferred Stock 4.78%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	4.78%	4.78%
Redemption Price Per Share (in dollars per share)	$ 102.80
Shares outstanding (in shares)	250,000	250,000
Preferred stock value outstanding	$ 25	$ 25
Aquarion Water Company | Series of Preferred Stock at 6%
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percentage)	6%
Redemption Price Per Share (in dollars per share)	$ 100
Shares outstanding (in shares)	13	23
Preferred stock value outstanding	$ 0	$ 0
Fair Value Adjustment | NSTAR Electric
Class of Stock [Line Items]
Preferred stock value outstanding	$ 3.6	$ 3.6

COMMON SHAREHOLDERS' EQUITY A_2

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Noncontrolling Interest [Line Items]
Dividends on preferred stock	$ 7,519	$ 7,519	$ 7,519
Noncontrolling interest - preferred stock of subsidiaries	155,569	155,570
CL&P and NSTAR Electric
Noncontrolling Interest [Line Items]
Dividends on preferred stock	$ 7,500	$ 7,500	$ 7,500

EARNINGS_(LOSS) PER SHARE - Nar

EARNINGS/(LOSS) PER SHARE - Narrative (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Antidilutive share awards excluded from the EPS computation (in shares)	0	0	0

EARNINGS_(LOSS) PER SHARE - Com

EARNINGS/(LOSS) PER SHARE - Components of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net (Loss)/Income Attributable to Common Shareholders	$ (442,240)	$ 1,404,875	$ 1,220,527
Weighted Average Common Shares Outstanding:
Basic (in shares)	349,580,638	346,783,444	343,972,926
Weighted Average Number of Shares Outstanding, Diluted, Adjustment [Abstract]
Share-Based Compensation Awards and Other (in shares)	259,843	463,324	658,130
Diluted (in shares)	349,840,481	347,246,768	344,631,056
Basic (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.27)	$ 4.05	$ 3.55
Diluted (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.26)	$ 4.05	$ 3.54

REVENUES - Operating Revenues D

REVENUES - Operating Revenues Disaggregated by Revenue Source (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	$ 11,890,600	$ 12,270,200	$ 9,815,000
Alternative Revenue Programs	(6,000)	5,300	41,700
Other Revenues	26,100	13,800	6,400
Operating Revenues	11,910,705	12,289,336	9,863,085
Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	6,344,300	6,142,700	5,123,600
Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,595,900	3,614,200	3,041,400
Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	524,000	559,200	499,700
Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	10,464,200	10,316,100	8,664,700
Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	467,000	436,000	453,200
Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	835,600	1,335,500	661,800
Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	119,500	110,600	114,000
Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	4,300	72,000	(78,700)
CL&P
Disaggregation of Revenue [Line Items]
Operating Revenues	4,578,804	4,817,744	3,637,412
NSTAR Electric
Disaggregation of Revenue [Line Items]
Operating Revenues	3,515,539	3,583,070	3,056,350
PSNH
Disaggregation of Revenue [Line Items]
Operating Revenues	1,447,873	1,474,799	1,177,248
Operating Segments | Electric Distribution
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	9,007,400	9,409,500	7,404,000
Alternative Revenue Programs	(54,300)	(15,400)	14,700
Other Revenues	20,400	11,200	4,900
Operating Revenues	8,973,500	9,405,300	7,423,600
Operating Segments | Electric Distribution | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	5,054,200	4,796,100	3,989,800
Operating Segments | Electric Distribution | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,893,200	2,903,300	2,486,100
Operating Segments | Electric Distribution | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	352,400	374,900	345,300
Operating Segments | Electric Distribution | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	8,299,800	8,074,300	6,821,200
Operating Segments | Electric Distribution | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Electric Distribution | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	625,000	1,190,900	575,800
Operating Segments | Electric Distribution | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	82,600	72,300	78,100
Operating Segments | Electric Distribution | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	72,000	(71,100)
Operating Segments | Natural Gas Distribution
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,182,200	2,199,500	1,752,300
Alternative Revenue Programs	35,500	14,800	37,000
Other Revenues	4,000	1,300	300
Operating Revenues	2,221,700	2,215,600	1,789,600
Operating Segments | Natural Gas Distribution | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,145,400	1,204,900	1,000,300
Operating Segments | Natural Gas Distribution | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	637,700	648,500	497,600
Operating Segments | Natural Gas Distribution | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	186,800	199,700	167,200
Operating Segments | Natural Gas Distribution | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,969,900	2,053,100	1,665,100
Operating Segments | Natural Gas Distribution | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Natural Gas Distribution | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	206,700	140,800	82,100
Operating Segments | Natural Gas Distribution | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	5,600	5,600	5,100
Operating Segments | Natural Gas Distribution | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Electric Transmission
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,796,400	1,715,300	1,759,900
Alternative Revenue Programs	118,900	92,700	(126,100)
Other Revenues	600	700	800
Operating Revenues	1,915,900	1,808,700	1,634,600
Operating Segments | Electric Transmission | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Electric Transmission | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Electric Transmission | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Electric Transmission | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Electric Transmission | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,777,500	1,700,500	1,751,300
Operating Segments | Electric Transmission | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Electric Transmission | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	14,600	14,100	13,600
Operating Segments | Electric Transmission | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	4,300	700	(5,000)
Operating Segments | Water Distribution
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	231,000	224,400	209,400
Alternative Revenue Programs	400	(2,500)	1,500
Other Revenues	1,100	600	400
Operating Revenues	232,500	222,500	211,300
Operating Segments | Water Distribution | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	144,700	141,700	133,500
Operating Segments | Water Distribution | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	69,800	66,500	62,800
Operating Segments | Water Distribution | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	4,500	4,700	4,300
Operating Segments | Water Distribution | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	219,000	212,900	200,600
Operating Segments | Water Distribution | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | Water Distribution | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,900	3,800	3,900
Operating Segments | Water Distribution | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	8,100	8,400	7,500
Operating Segments | Water Distribution | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	(700)	(2,600)
Operating Segments | CL&P
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	5,077,600	5,343,200	4,238,900
Alternative Revenue Programs	66,800	56,500	(78,900)
Other Revenues	9,600	1,800	400
Operating Segments | CL&P | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	2,597,800	2,397,200	1,994,200
Operating Segments | CL&P | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,082,100	1,067,900	890,600
Operating Segments | CL&P | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	137,200	146,400	131,400
Operating Segments | CL&P | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,817,100	3,611,500	3,016,200
Operating Segments | CL&P | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	794,700	755,100	863,300
Operating Segments | CL&P | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	429,100	873,700	408,800
Operating Segments | CL&P | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	32,400	30,200	26,700
Operating Segments | CL&P | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	4,300	72,700	(76,100)
Operating Segments | NSTAR Electric
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	4,129,400	4,127,300	3,541,600
Alternative Revenue Programs	(52,000)	700	(15,100)
Other Revenues	8,400	7,200	3,400
Operating Segments | NSTAR Electric | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,691,000	1,601,800	1,375,800
Operating Segments | NSTAR Electric | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,442,300	1,457,400	1,265,000
Operating Segments | NSTAR Electric | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	123,200	135,800	119,100
Operating Segments | NSTAR Electric | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,256,500	3,195,000	2,759,900
Operating Segments | NSTAR Electric | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	692,000	670,400	616,300
Operating Segments | NSTAR Electric | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	131,800	215,000	109,200
Operating Segments | NSTAR Electric | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	49,100	46,900	56,200
Operating Segments | NSTAR Electric | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Operating Segments | PSNH
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,600,000	1,659,600	1,387,600
Alternative Revenue Programs	49,800	20,100	(17,400)
Other Revenues	3,000	2,900	1,900
Operating Segments | PSNH | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	765,400	797,100	619,800
Operating Segments | PSNH | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	369,600	380,800	332,200
Operating Segments | PSNH | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	92,000	92,700	94,800
Operating Segments | PSNH | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,227,000	1,270,600	1,046,800
Operating Segments | PSNH | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	290,800	275,000	271,700
Operating Segments | PSNH | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	64,100	102,200	57,800
Operating Segments | PSNH | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	18,100	11,800	11,300
Operating Segments | PSNH | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Other
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,636,600	1,435,500	1,354,000
Alternative Revenue Programs	0	0	0
Other Revenues	0	0	0
Operating Revenues	1,636,600	1,435,500	1,354,000
Other | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Other | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Other | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Other | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Other | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	86,600
Other | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Other | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,636,600	1,435,500	1,267,400
Other | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(2,963,000)	(2,714,000)	(2,664,600)
Alternative Revenue Programs	(106,500)	(84,300)	114,600
Other Revenues	0	0	0
Operating Revenues	(3,069,500)	(2,798,300)	(2,550,000)
Eliminations | Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Eliminations | Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(4,800)	(4,100)	(5,100)
Eliminations | Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(19,700)	(20,100)	(17,100)
Eliminations | Total Retail Tariff Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(24,500)	(24,200)	(22,200)
Eliminations | Wholesale Transmission Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(1,310,500)	(1,264,500)	(1,384,700)
Eliminations | Wholesale Market Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Eliminations | Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(1,628,000)	(1,425,300)	(1,257,700)
Eliminations | Amortization of Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0
Consolidations Eliminations | CL&P
Disaggregation of Revenue [Line Items]
Operating Revenues	(575,200)	(583,800)	(523,000)
Consolidations Eliminations | NSTAR Electric
Disaggregation of Revenue [Line Items]
Operating Revenues	(570,300)	(552,100)	(473,500)
Consolidations Eliminations | PSNH
Disaggregation of Revenue [Line Items]
Operating Revenues	$ (204,900)	$ (207,800)	$ (194,900)

REVENUES - Narrative (Details)

REVENUES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Apr. 28, 2021
Loss Contingencies [Line Items]
Revenue	$ 11,890,600	$ 12,270,200	$ 9,815,000
Loss related to litigation settlement	0	(72,041)	81,274
Lease revenue	$ 4,600	$ 4,000	$ 4,800
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Income, Net	Other Income, Net	Other Income, Net
CL&P
Loss Contingencies [Line Items]
Loss related to litigation settlement	$ 0	$ (72,041)	$ 81,274
Lease revenue	700	800	800
NSTAR Electric
Loss Contingencies [Line Items]
Lease revenue	2,500	2,500	3,100
Amortization of Revenues Subject to Refund
Loss Contingencies [Line Items]
Revenue	4,300	72,000	(78,700)
Operating Segments | CL&P
Loss Contingencies [Line Items]
Revenue	5,077,600	5,343,200	4,238,900
Operating Segments | NSTAR Electric
Loss Contingencies [Line Items]
Revenue	4,129,400	4,127,300	3,541,600
Operating Segments | Amortization of Revenues Subject to Refund | CL&P
Loss Contingencies [Line Items]
Revenue	4,300	72,700	(76,100)
Operating Segments | Amortization of Revenues Subject to Refund | NSTAR Electric
Loss Contingencies [Line Items]
Revenue	$ 0	$ 0	0
Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Loss related to litigation settlement			103,600
Unfavorable Regulatory Action | CL&P
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact, non-compliance with performance standards				$ 28,400
Unfavorable Regulatory Action | Operating Segments | Amortization of Revenues Subject to Refund | CL&P
Loss Contingencies [Line Items]
Revenue			93,400
Sales | Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Loss related to litigation settlement			65,000
Sales | Unfavorable Regulatory Action | CL&P
Loss Contingencies [Line Items]
Loss related to litigation settlement			$ 65,000

SEGMENT INFORMATION - Narrative

SEGMENT INFORMATION - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) reportableSegment
Segment Reporting Information [Line Items]
Number of reportable segments	1
Yankee Gas, NSTAR Gas and EGMA
Segment Reporting Information [Line Items]
Amount of natural gas transmission purchased | $	$ 77.7
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

SEGMENT INFORMATION - Schedule

SEGMENT INFORMATION - Schedule of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating Revenues			$ 11,910,705	$ 12,289,336	$ 9,863,085
Depreciation and Amortization			(815,700)	(1,643,100)	(1,335,000)
Other Operating Expenses			(8,695,700)	(8,448,000)	(6,534,800)
Operating Income			2,399,335	2,198,154	1,993,321
Interest Expense			(855,441)	(678,274)	(582,334)
Impairments of Offshore Wind Investments	$ (1,766,000)	$ (401,000)	(2,167,000)	0	0
Interest Income			94,200	50,500	25,600
Other Income, Net			253,900	295,600	135,700
Income Tax (Expense)/Benefit			(159,684)	(453,574)	(344,223)
Net (Loss)/Income			(434,700)	1,412,400	1,228,000
Net Income Attributable to Noncontrolling Interests			(7,519)	(7,519)	(7,519)
Net Income Attributable to Common Shareholders			(442,240)	1,404,875	1,220,527
Total Assets (as of)	55,612,245		55,612,245	53,230,900
Cash Flows Used for Investments in Plant			4,336,800	3,441,900	3,175,100
Operating Segments | Electric Distribution
Segment Reporting Information [Line Items]
Operating Revenues			8,973,500	9,405,300	7,423,600
Depreciation and Amortization			(18,200)	(970,400)	(737,800)
Other Operating Expenses			(8,104,600)	(7,663,700)	(5,970,000)
Operating Income			850,700	771,200	715,800
Interest Expense			(291,700)	(253,100)	(236,400)
Impairments of Offshore Wind Investments			0
Interest Income			74,500	45,100	20,700
Other Income, Net			136,200	180,400	78,100
Income Tax (Expense)/Benefit			(157,100)	(146,200)	(103,500)
Net (Loss)/Income			612,600	597,400	474,700
Net Income Attributable to Noncontrolling Interests			(4,600)	(4,600)	(4,600)
Net Income Attributable to Common Shareholders			608,000	592,800	470,100
Total Assets (as of)	29,426,400		29,426,400	27,365,000
Cash Flows Used for Investments in Plant			1,668,100	1,172,600	1,053,300
Operating Segments | Natural Gas Distribution
Segment Reporting Information [Line Items]
Operating Revenues			2,221,700	2,215,600	1,789,600
Depreciation and Amortization			(214,200)	(157,600)	(142,300)
Other Operating Expenses			(1,662,600)	(1,727,000)	(1,345,400)
Operating Income			344,900	331,000	301,900
Interest Expense			(85,700)	(71,400)	(58,600)
Impairments of Offshore Wind Investments			0
Interest Income			18,200	10,200	4,500
Other Income, Net			20,400	33,600	17,900
Income Tax (Expense)/Benefit			(73,000)	(69,200)	(60,900)
Net (Loss)/Income			224,800	234,200	204,800
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			224,800	234,200	204,800
Total Assets (as of)	8,775,300		8,775,300	8,084,900
Cash Flows Used for Investments in Plant			844,100	710,300	721,100
Operating Segments | Electric Transmission
Segment Reporting Information [Line Items]
Operating Revenues			1,915,900	1,808,700	1,634,600
Depreciation and Amortization			(371,200)	(337,400)	(300,300)
Other Operating Expenses			(550,500)	(548,400)	(496,200)
Operating Income			994,200	922,900	838,100
Interest Expense			(163,700)	(145,500)	(133,200)
Impairments of Offshore Wind Investments			0
Interest Income			400	500	2,200
Other Income, Net			41,200	37,900	19,800
Income Tax (Expense)/Benefit			(225,800)	(216,300)	(179,400)
Net (Loss)/Income			646,300	599,500	547,500
Net Income Attributable to Noncontrolling Interests			(2,900)	(2,900)	(2,900)
Net Income Attributable to Common Shareholders			643,400	596,600	544,600
Total Assets (as of)	14,806,500		14,806,500	13,369,500
Cash Flows Used for Investments in Plant			1,406,300	1,144,000	1,024,100
Operating Segments | Water Distribution
Segment Reporting Information [Line Items]
Operating Revenues			232,500	222,500	211,300
Depreciation and Amortization			(56,000)	(50,900)	(46,100)
Other Operating Expenses			(117,100)	(111,800)	(101,400)
Operating Income			59,400	59,800	63,800
Interest Expense			(38,500)	(34,700)	(32,000)
Impairments of Offshore Wind Investments			0
Interest Income			0	0	0
Other Income, Net			5,900	8,500	3,300
Income Tax (Expense)/Benefit			6,300	3,200	1,700
Net (Loss)/Income			33,100	36,800	36,800
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			33,100	36,800	36,800
Total Assets (as of)	2,944,800		2,944,800	2,783,800
Cash Flows Used for Investments in Plant			167,000	154,400	137,200
Other
Segment Reporting Information [Line Items]
Operating Revenues			1,636,600	1,435,500	1,354,000
Depreciation and Amortization			(158,800)	(132,600)	(113,100)
Other Operating Expenses			(1,329,800)	(1,189,100)	(1,170,400)
Operating Income			148,000	113,800	70,500
Interest Expense			(425,300)	(247,800)	(168,800)
Impairments of Offshore Wind Investments			(2,167,000)
Interest Income			150,600	66,300	46,000
Other Income, Net			(261,800)	1,600,800	1,363,900
Income Tax (Expense)/Benefit			289,900	(25,100)	(2,100)
Net (Loss)/Income			(2,265,600)	1,508,000	1,309,500
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			(2,265,600)	1,508,000	1,309,500
Total Assets (as of)	26,337,700		26,337,700	26,365,200
Cash Flows Used for Investments in Plant			251,300	260,600	239,400
Eliminations
Segment Reporting Information [Line Items]
Operating Revenues			(3,069,500)	(2,798,300)	(2,550,000)
Depreciation and Amortization			2,700	5,800	4,600
Other Operating Expenses			3,068,900	2,792,000	2,548,600
Operating Income			2,100	(500)	3,200
Interest Expense			149,500	74,200	46,600
Impairments of Offshore Wind Investments			0
Interest Income			(149,500)	(71,600)	(47,800)
Other Income, Net			312,000	(1,565,600)	(1,347,300)
Income Tax (Expense)/Benefit			0	0	0
Net (Loss)/Income			314,100	(1,563,500)	(1,345,300)
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			314,100	(1,563,500)	(1,345,300)
Total Assets (as of)	$ (26,678,500)		(26,678,500)	(24,737,500)
Cash Flows Used for Investments in Plant			$ 0	$ 0	$ 0

GOODWILL - Summary of Goodwill

GOODWILL - Summary of Goodwill by Reportable Segment (Details) - USD ($) $ in Thousands		12 Months Ended
	Oct. 03, 2022	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Roll Forward]
Beginning Balance		$ 4,522,632	$ 4,477,300
Ending Balance		4,532,100	4,522,632
New England Service Company (NESC)
Goodwill [Roll Forward]
Measurement Period Adjustments			500
The Torrington Water Company (TWC)
Goodwill [Roll Forward]
Goodwill acquired			44,800
Water Acquisitions
Goodwill [Roll Forward]
Goodwill acquired		9,500
Electric Distribution
Goodwill [Roll Forward]
Beginning Balance		2,543,600	2,543,600
Ending Balance		2,543,600	2,543,600
Electric Distribution | New England Service Company (NESC)
Goodwill [Roll Forward]
Measurement Period Adjustments			0
Electric Distribution | The Torrington Water Company (TWC)
Goodwill [Roll Forward]
Goodwill acquired			0
Electric Distribution | Water Acquisitions
Goodwill [Roll Forward]
Goodwill acquired		0
Electric Transmission
Goodwill [Roll Forward]
Beginning Balance		576,800	576,800
Ending Balance		576,800	576,800
Electric Transmission | New England Service Company (NESC)
Goodwill [Roll Forward]
Measurement Period Adjustments			0
Electric Transmission | The Torrington Water Company (TWC)
Goodwill [Roll Forward]
Goodwill acquired			0
Electric Transmission | Water Acquisitions
Goodwill [Roll Forward]
Goodwill acquired		0
Natural Gas Distribution
Goodwill [Roll Forward]
Beginning Balance		451,000	451,000
Ending Balance		451,000	451,000
Natural Gas Distribution | New England Service Company (NESC)
Goodwill [Roll Forward]
Measurement Period Adjustments			0
Natural Gas Distribution | The Torrington Water Company (TWC)
Goodwill [Roll Forward]
Goodwill acquired			0
Natural Gas Distribution | Water Acquisitions
Goodwill [Roll Forward]
Goodwill acquired		0
Water Distribution
Goodwill [Roll Forward]
Beginning Balance		951,200	905,900
Ending Balance		960,700	951,200
Water Distribution | New England Service Company (NESC)
Goodwill [Roll Forward]
Measurement Period Adjustments		500	500
Goodwill acquired		22,200
Water Distribution | The Torrington Water Company (TWC)
Goodwill [Roll Forward]
Goodwill acquired	$ 44,800		$ 44,800
Water Distribution | Water Acquisitions
Goodwill [Roll Forward]
Goodwill acquired		$ 9,500

GOODWILL - Narrative (Details)

GOODWILL - Narrative (Details)			12 Months Ended
	Oct. 01, 2023 USD ($)	Oct. 03, 2022 USD ($)	Dec. 31, 2023 USD ($) acquistion	Dec. 31, 2022 USD ($)
Goodwill [Line Items]
Impairment loss	$ 0
The Torrington Water Company (TWC)
Goodwill [Line Items]
Goodwill acquired				$ 44,800,000
New England Service Company (NESC)
Goodwill [Line Items]
NESC Measurement Period Adjustments				500,000
Water Acquisitions
Goodwill [Line Items]
Goodwill acquired			$ 9,500,000
Water Distribution | The Torrington Water Company (TWC)
Goodwill [Line Items]
Goodwill acquired		$ 44,800,000		44,800,000
Water Distribution | New England Service Company (NESC)
Goodwill [Line Items]
Goodwill acquired			22,200,000
NESC Measurement Period Adjustments			500,000	$ 500,000
Water Distribution | Water Acquisitions
Goodwill [Line Items]
Goodwill acquired			$ 9,500,000
Number of water acquisitions | acquistion			2

SCHEDULE I - FINANCIAL INFORM_2

SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - BALANCE SHEET (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current Assets:
Cash	$ 53,873	$ 47,597
Accounts Receivable from Subsidiaries	1,431,531	1,517,138
Prepayments and Other Current Assets	355,762	382,603
Total Current Assets	4,247,994	4,223,198
Deferred Debits and Other Assets:
Carrying Value as of December 31, 2023	660,473	2,176,080
Goodwill	4,532,100	4,522,632	$ 4,477,300
Other Long-Term Assets	592,080	541,344
Total Deferred Debits and Other Assets	11,865,644	12,894,882
Total Assets (as of)	55,612,245	53,230,900
Current Liabilities:
Notes Payable	1,930,422	1,442,200
Long-Term Debt – Current Portion	824,847	1,320,129
Accounts Payable to Subsidiaries	1,869,187	2,113,905
Other Current Liabilities	1,081,981	989,053
Total Current Liabilities	6,341,397	6,799,283
Liabilities, Noncurrent [Abstract]
Other Long-Term Liabilities	961,239	888,081
Total Deferred Credits and Other Liabilities	10,985,489	10,668,403
Capitalization:
Long-Term Debt	23,588,616	19,723,994
Common Shareholders' Equity:
Capital Surplus, Paid in	8,460,876	8,401,731
Retained Earnings	4,142,515	5,527,153
Accumulated Other Comprehensive Loss	(33,737)	(39,421)
Treasury Stock	(195,682)	(216,225)
Common Shareholders' Equity	14,173,892	15,473,158	$ 14,599,844	$ 14,063,566
Total Liabilities and Capitalization	55,612,245	53,230,900
Eversource
Current Assets:
Cash	542	971
Accounts Receivable from Subsidiaries	60,191	53,338
Notes Receivable from Subsidiaries	2,045,570	1,074,800
Prepayments and Other Current Assets	103,735	23,597
Total Current Assets	2,210,038	1,152,706
Deferred Debits and Other Assets:
Carrying Value as of December 31, 2023	17,977,812	18,379,840
Notes Receivable from Subsidiaries	2,296,500	1,896,500
Accumulated Deferred Income Taxes	10,131	0
Goodwill	3,852,524	3,852,524
Other Long-Term Assets	28,287	108,867
Total Deferred Debits and Other Assets	24,165,254	24,237,731
Total Assets (as of)	26,375,292	25,390,437
Current Liabilities:
Notes Payable	1,564,575	1,442,200
Long-Term Debt – Current Portion	364,653	1,207,047
Accounts Payable to Subsidiaries	38,051	33,530
Accrued Interest	106,070	72,951
Other Current Liabilities	41,268	39,856
Total Current Liabilities	2,114,617	2,795,584
Liabilities, Noncurrent [Abstract]
Accumulated Deferred Income Taxes	0	8,498
Other Long-Term Liabilities	134,432	140,393
Total Deferred Credits and Other Liabilities	134,432	148,891
Capitalization:
Long-Term Debt	9,952,351	6,972,804
Common Shareholders' Equity:
Common Shares	1,799,920	1,799,920
Capital Surplus, Paid in	8,460,876	8,401,731
Retained Earnings	4,142,515	5,527,153
Accumulated Other Comprehensive Loss	(33,737)	(39,421)
Treasury Stock	(195,682)	(216,225)
Common Shareholders' Equity	14,173,892	15,473,158
Total Liabilities and Capitalization	$ 26,375,292	$ 25,390,437

SCHEDULE I - FINANCIAL INFORM_3

SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - STATEMENTS OF (LOSS)/INCOME (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Income Statements, Captions [Line Items]
Operating Revenues	$ 11,910,705	$ 12,289,336	$ 9,863,085
Operating Expenses:
Other	1,895,703	1,865,328	1,739,685
Operating Income (Loss)	2,399,335	2,198,154	1,993,321
Interest Expense	855,441	678,274	582,334
Other Income, Net:
Equity in (Losses)/Earnings of Subsidiaries	15,500	22,900	14,200
Other (Loss)/Income, Net	348,069	346,088	161,282
(Loss)/Income Before Income Tax Benefit	(275,037)	1,865,968	1,572,269
Income Tax Benefit	159,684	453,574	344,223
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Basic (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.27)	$ 4.05	$ 3.55
Diluted (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.26)	$ 4.05	$ 3.54
Weighted Average Common Shares Outstanding:
Basic (in shares)	349,580,638	346,783,444	343,972,926
Diluted (in shares)	349,840,481	347,246,768	344,631,056
Eversource
Condensed Income Statements, Captions [Line Items]
Operating Revenues	$ 840	$ 0	$ 0
Operating Expenses:
Other	12,769	26,708	43,048
Operating Income (Loss)	(11,929)	(26,708)	(43,048)
Interest Expense	397,281	237,773	163,613
Other Income, Net:
Equity in (Losses)/Earnings of Subsidiaries	(312,040)	1,565,474	1,345,199
Other, Net	188,003	79,383	47,802
Other (Loss)/Income, Net	(124,037)	1,644,857	1,393,001
(Loss)/Income Before Income Tax Benefit	(533,247)	1,380,376	1,186,340
Income Tax Benefit	(91,007)	(24,499)	(34,187)
Net (Loss)/Income	$ (442,240)	$ 1,404,875	$ 1,220,527
Basic (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.27)	$ 4.05	$ 3.55
Diluted (Loss)/Earnings Per Common Share (in dollars per share)	$ (1.26)	$ 4.05	$ 3.54
Weighted Average Common Shares Outstanding:
Basic (in shares)	349,580,638	346,783,444	343,972,926
Diluted (in shares)	349,840,481	347,246,768	344,631,056

SCHEDULE I - FINANCIAL INFORM_4

SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - STATEMENTS OF COMPREHENSIVE (LOSS)/INCOME (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Statement of Income Captions [Line Items]
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Other Comprehensive Income/(Loss), Net of Tax:
Qualified Cash Flow Hedging Instruments	20	20	972
Changes in Unrealized Gains/(Losses) on Marketable Securities	1,252	(1,636)	(671)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	4,412	4,470	33,835
Other Comprehensive Income, Net of Tax	5,684	2,854	34,136
Comprehensive (Loss)/Income	(436,556)	1,407,729	1,254,663
Eversource
Condensed Statement of Income Captions [Line Items]
Net (Loss)/Income	(442,240)	1,404,875	1,220,527
Other Comprehensive Income/(Loss), Net of Tax:
Qualified Cash Flow Hedging Instruments	20	20	972
Changes in Unrealized Gains/(Losses) on Marketable Securities	1,252	(1,636)	(671)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	4,412	4,470	33,835
Other Comprehensive Income, Net of Tax	5,684	2,854	34,136
Comprehensive (Loss)/Income	$ (436,556)	$ 1,407,729	$ 1,254,663

SCHEDULE I - FINANCIAL INFORM_5

SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - STATEMENT OF CASH FLOW (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net (Loss)/Income	$ (434,700)	$ 1,412,400	$ 1,228,000
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Equity in Losses/(Earnings) of Subsidiaries	(15,500)	(22,900)	(14,200)
Deferred Income Taxes	85,405	346,779	347,056
Other	(53,026)	(39,192)	(64,640)
Receivables and Unbilled Revenues, Net	(124,393)	(470,593)	(135,505)
Taxes Receivable/Accrued, Net	36,357	18,358	(110,621)
Other Current Assets and Liabilities, Net	(66,202)	(45,583)	3,710
Net Cash Flows Provided by Operating Activities	1,646,161	2,401,293	1,962,600
Investing Activities:
Other Investing Activities	(2,897)	20,420	22,178
Net Cash Flows Used in Investing Activities	(4,870,732)	(4,130,490)	(3,447,374)
Financing Activities:
Issuance of Common Shares, Net of Issuance Costs	0	197,058	0
Cash Dividends on Common Shares	(918,995)	(860,033)	(805,439)
Issuance of Long-Term Debt	5,198,345	4,045,000	3,230,000
Retirement of Long-Term Debt	(2,008,470)	(1,175,000)	(1,142,500)
Other Financing Activities	(46,466)	(48,185)	(46,625)
Net Cash Flows Provided by Financing Activities	2,869,237	2,029,941	1,440,832
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(355,334)	300,744	(43,942)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	521,752	221,008	264,950
Cash, Cash Equivalents and Restricted Cash - End of Year	166,418	521,752	221,008
Cash Paid/(Received) During the Year for:
Interest	783,200	636,200	568,700
Income Taxes	39,200	77,900	121,600
Eversource
Operating Activities:
Net (Loss)/Income	(442,240)	1,404,875	1,220,527
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Equity in Losses/(Earnings) of Subsidiaries	312,040	(1,565,474)	(1,345,199)
Cash Dividends Received from Subsidiaries	1,027,400	855,600	1,037,100
Deferred Income Taxes	(22,256)	25,823	20,293
Other	(12,834)	26,455	36,910
Receivables and Unbilled Revenues, Net	(6,853)	(9,935)	(3,758)
Taxes Receivable/Accrued, Net	(80,968)	(21,627)	(19,455)
Accounts Payable to Subsidiaries	4,521	(4,079)	19,185
Other Current Assets and Liabilities, Net	35,357	35,090	8,144
Net Cash Flows Provided by Operating Activities	814,167	746,728	973,747
Investing Activities:
Capital Contributions to Subsidiaries	(1,369,700)	(1,499,300)	(1,033,000)
Return of Capital from Subsidiaries	438,000	12,000	178,800
Increase in Notes Receivable from Subsidiaries	(1,578,100)	(724,400)	(140,200)
Other Investing Activities	147,567	(1,289)	(3,196)
Net Cash Flows Used in Investing Activities	(2,362,233)	(2,212,989)	(997,596)
Financing Activities:
Issuance of Common Shares, Net of Issuance Costs	0	197,058	0
Cash Dividends on Common Shares	(918,995)	(860,033)	(805,439)
Issuance of Long-Term Debt	3,350,000	2,800,000	1,000,000
Retirement of Long-Term Debt	(1,200,000)	(750,000)	(450,000)
Increase (Decrease) in Notes Payable to Eversource Parent	329,705	99,250	288,625
Other Financing Activities	(13,076)	(19,193)	(9,545)
Net Cash Flows Provided by Financing Activities	1,547,634	1,467,082	23,641
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(432)	821	(208)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	1,047	226	434
Cash, Cash Equivalents and Restricted Cash - End of Year	615	1,047	226
Cash Paid/(Received) During the Year for:
Interest	366,645	215,053	164,568
Income Taxes	$ 23,984	$ (20,992)	$ (51,277)

SCHEDULE II - VALUATION AND Q_2

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 486,297	$ 417,406	$ 358,851
Additions, Charged to Costs and Expense	72,468	61,876	60,886
Additions, Charged to Other Accounts	158,205	112,533	110,572
Deductions	162,515	105,518	112,903
Balance at end of period	554,455	486,297	417,406
CL&P
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	225,320	181,319	157,447
Additions, Charged to Costs and Expense	11,675	15,578	13,495
Additions, Charged to Other Accounts	126,360	59,485	57,779
Deductions	67,325	31,062	47,402
Balance at end of period	296,030	225,320	181,319
NSTAR Electric
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	94,958	97,005	91,583
Additions, Charged to Costs and Expense	22,791	21,550	16,649
Additions, Charged to Other Accounts	17,488	12,412	20,064
Deductions	38,211	36,009	31,291
Balance at end of period	97,026	94,958	97,005
PSNH
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	29,236	24,331	17,157
Additions, Charged to Costs and Expense	3,989	9,211	13,113
Additions, Charged to Other Accounts	(8,735)	2,539	3,135
Deductions	10,168	6,845	9,074
Balance at end of period	$ 14,322	$ 29,236	$ 24,331