EMPLOYEE BENEFITS (Tables)

12 Months Ended

Dec. 31, 2022

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,
	2022								2021
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Change in Benefit Obligation:
Benefit Obligation as of Beginning of Year	$	(6,729.7)	$	(1,330.9)	$	(1,448.4)	$	(721.0)	$	(7,045.3)	$	(1,477.3)	$	(1,517.9)	$	(748.7)
Service Cost	(70.1)		(18.7)		(13.8)		(6.9)		(85.8)		(23.0)		(15.8)		(8.9)
Interest Cost	(154.5)		(31.3)		(32.8)		(16.9)		(130.0)		(27.3)		(26.8)		(14.5)
Actuarial Gain	1,385.8		284.1		295.5		156.7		177.1		127.8		20.8		14.7
Benefits Paid - Pension	302.5		63.3		68.4		33.9		309.5		64.6		68.7		34.7
Benefits Paid - Lump Sum	33.0		—		14.8		1.0		34.7		—		15.6		—
Benefits Paid - SERP	12.9		0.3		0.2		0.4		10.1		0.3		0.2		0.4
Employee Transfers	—		3.2		5.7		(3.4)		—		4.0		6.8		1.3
Benefit Obligation as of End of Year	$	(5,220.1)	$	(1,030.0)	$	(1,110.4)	$	(556.2)	$	(6,729.7)	$	(1,330.9)	$	(1,448.4)	$	(721.0)
Change in Pension Plan Assets:
Fair Value of Pension Plan Assets as of   Beginning of Year	$	6,495.5	$	1,323.8	$	1,596.0	$	694.6	$	5,409.2	$	1,043.1	$	1,345.1	$	593.7
Employer Contributions	80.0		—		15.0		—		180.0		98.9		30.0		—
Actual Return on Pension Plan Assets	(433.6)		(85.3)		(103.3)		(45.1)		1,250.5		250.4		312.0		136.9
Benefits Paid - Pension	(302.5)		(63.3)		(68.4)		(33.9)		(309.5)		(64.6)		(68.7)		(34.7)
Benefits Paid - Lump Sum	(33.0)		—		(14.8)		(1.0)		(34.7)		—		(15.6)		—
Employee Transfers	—		(3.2)		(5.7)		3.4		—		(4.0)		(6.8)		(1.3)
Fair Value of Pension Plan Assets as of End of Year	$	5,806.4	$	1,172.0	$	1,418.8	$	618.0	$	6,495.5	$	1,323.8	$	1,596.0	$	694.6
Funded Status as of December 31st	$	586.3	$	142.0	$	308.4	$	61.8	$	(234.2)	$	(7.1)	$	147.6	$	(26.4)

	PBOP
	As of December 31,
	2022								2021
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Change in Benefit Obligation:
Benefit Obligation as of Beginning of Year	$	(884.3)	$	(165.5)	$	(238.4)	$	(92.3)	$	(993.9)	$	(178.6)	$	(260.5)	$	(109.5)
Service Cost	(11.6)		(2.0)		(2.0)		(1.1)		(13.5)		(2.3)		(2.4)		(1.2)
Interest Cost	(20.2)		(3.7)		(5.3)		(2.2)		(17.4)		(3.2)		(4.4)		(1.8)
Actuarial Gain	173.6		33.0		39.4		15.2		81.4		5.8		11.5		14.6
Benefits Paid	52.1		10.4		16.6		6.0		51.7		10.9		16.3		5.6
Employee Transfers	—		(0.1)		0.2		(0.2)		—		1.9		1.1		—
Impact of Acquisitions	(3.3)		—		—		—		7.4		—		—		—
Benefit Obligation as of End of Year	$	(693.7)	$	(127.9)	$	(189.5)	$	(74.6)	$	(884.3)	$	(165.5)	$	(238.4)	$	(92.3)
Change in Plan Assets:
Fair Value of Plan Assets as of Beginning of Year	$	1,138.3	$	145.7	$	530.0	$	88.0	$	1,004.1	$	134.1	$	464.6	$	79.4
Actual Return on Plan Assets	(119.6)		(15.0)		(57.0)		(9.8)		183.2		24.1		84.2		14.2
Employer Contributions	3.1		—		—		—		2.3		—		—		—
Benefits Paid	(51.7)		(10.4)		(16.6)		(6.0)		(51.3)		(10.9)		(16.3)		(5.6)
Employee Transfers	—		0.3		(0.3)		0.1		—		(1.6)		(2.5)		—
Fair Value of Plan Assets as of End of Year	$	970.1	$	120.6	$	456.1	$	72.3	$	1,138.3	$	145.7	$	530.0	$	88.0
Funded Status as of December 31st	$	276.4	$	(7.3)	$	266.6	$	(2.3)	$	254.0	$	(19.8)	$	291.6	$	(4.3)

Schedule of Defined Benefit Plans

As of December 31, 2022 and 2021, the accumulated benefit obligation for the Pension and SERP Plans is as follows:

(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2022	$	4,911.6	$	960.7	$	1,055.1	$	516.9
2021	6,337.3		1,241.1		1,376.1		670.3

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,
	2022								2021
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Prepaid Pension	$	756.7	$	147.9	$	310.2	$	66.4	$	—	$	0.4	$	149.8	$	—
Prepaid PBOP	288.8		—		266.6		—		272.0		—		291.6		—
Prepaid Pension and PBOP	$	1,045.5	$	147.9	$	576.8	$	66.4	$	272.0	$	0.4	$	441.4	$	—
Accrued Pension	$	3.7	$	—	$	—	$	—	$	58.1	$	—	$	—	$	20.6
Accrued SERP	166.7		5.9		1.8		4.6		176.1		7.5		2.2		5.8
Accrued PBOP	12.4		7.3		—		2.3		18.0		19.8		—		4.3
Less: Accrued SERP - current portion	(47.3)		(0.3)		(0.2)		(0.4)		(9.7)		(0.5)		(0.2)		(0.5)
Accrued Pension, SERP and PBOP	$	135.5	$	12.9	$	1.6	$	6.5	$	242.5	$	26.8	$	2.0	$	30.2

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,
		2022			2021			2022	2021
Discount Rate		5.1%	—	5.2%	2.8%	—	3.0%	5.2%	2.91%	—	2.92%
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,
	2022			2021			2020			2022			2021			2020
Discount Rate	2.2%	—	3.2%	1.5%	—	3.0%	2.6%	—	3.5%	2.3%	—	3.3%	1.8%	—	3.1%	2.7%	—	3.6%
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, 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)

	Pension and SERP								PBOP
	For the Year Ended December 31, 2020								For the Year Ended December 31, 2020
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Service Cost	$	76.2	$	21.8	$	15.4	$	8.2	$	10.2	$	1.7	$	2.1	$	0.9
Interest Cost	177.8		37.3		38.6		19.4		24.6		4.4		6.6		2.8
Expected Return on Plan Assets	(400.3)		(79.2)		(103.0)		(44.7)		(73.6)		(9.9)		(34.0)		(5.7)
Actuarial Loss	202.0		39.2		55.2		15.6		8.4		1.1		2.5		0.8
Prior Service Cost/(Credit)	1.2		—		0.3		—		(21.2)		1.1		(17.0)		0.4
Total Net Periodic Benefit Plan Expense/(Income)	$	56.9	$	19.1	$	6.5	$	(1.5)	$	(51.6)	$	(1.6)	$	(39.8)	$	(0.8)
Intercompany Expense/(Income) Allocations	N/A		$	9.1	$	8.9	$	2.9	N/A		$	(1.1)	$	(1.4)	$	(0.5)

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)	2022		2021		2022		2021		2022		2021		2022		2021
Actuarial (Gains)/Losses Arising During the Year	$	(431.6)	$	(961.7)	$	4.6	$	(28.4)	$	36.8	$	(181.5)	$	(0.8)	$	(4.0)
Actuarial Losses Reclassified as Net Periodic Benefit Expense	(107.0)		(231.2)		(9.0)		(12.7)		—		(8.5)		—		(0.4)
Prior Service (Cost)/Credit Reclassified as Net Periodic   Benefit (Expense)/Income	(1.2)		(1.3)		(0.2)		(0.1)		21.8		21.1		(0.1)		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, 2022 and 2021:

	Regulatory Assets as of December 31,				AOCI as of December 31,
(Millions of Dollars)	2022		2021		2022		2021
Pension and SERP
Actuarial Loss	$	888.7	$	1,427.3	$	61.9	$	66.3
Prior Service Cost	4.1		5.3		0.4		0.6
PBOP
Actuarial Loss	$	81.8	$	45.0	$	2.7	$	3.5
Prior Service (Credit)/Cost	(108.3)		(130.1)		0.9		1.0

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)	2023		2024		2025		2026		2027		2028 - 2032
Pension and SERP	$	401.4	$	374.4	$	380.1	$	383.0	$	384.1	$	1,901.7
PBOP	57.9		57.3		56.6		55.5		54.4		253.7

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,
	2022				2021
	Eversource Pension Plan and PBOP Plan				Eversource Pension Plan and PBOP Plan
	Target Asset Allocation		Assumed Rate of Return		Target Asset Allocation		Assumed Rate of Return
Equity Securities:
United States	15.0	%	8.5	%	15.0	%	8.5	%
Global	10.0	%	8.75	%	10.0	%	8.75	%
Non-United States	8.0	%	8.5	%	8.0	%	8.5	%
Emerging Markets	4.0	%	10.0	%	4.0	%	10.0	%
Debt Securities:
Fixed Income	13.0	%	4.0	%	13.0	%	4.0	%
Public High Yield Fixed Income	4.0	%	6.5	%	4.0	%	6.5	%
Private Debt	13.0	%	9.0	%	13.0	%	9.0	%
Private Equity	18.0	%	12.0	%	18.0	%	12.0	%
Real Assets	15.0	%	7.5	%	15.0	%	7.5	%

The following table presents, 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)	2022								2021
Asset Category:	Level 1		Level 2		Uncategorized		Total		Level 1		Level 2		Uncategorized		Total
Equity Securities	$	407.7	$	—	$	1,102.2	$	1,509.9	$	722.5	$	—	$	1,385.2	$	2,107.7
Fixed Income (1)	277.1		78.5		1,598.8		1,954.4		139.6		233.8		1,689.1		2,062.5
Private Equity	—		—		1,684.9		1,684.9		—		—		1,702.7		1,702.7
Real Assets	181.8		—		731.0		912.8		218.3		—		702.8		921.1
Total	$	866.6	$	78.5	$	5,116.9	$	6,062.0	$	1,080.4	$	233.8	$	5,479.8	$	6,794.0
Less:  401(h) PBOP Assets (2)							(255.6)								(298.5)
Total Pension Assets							$	5,806.4							$	6,495.5

	PBOP Plan
	Fair Value Measurements as of December 31,
(Millions of Dollars)	2022								2021
Asset Category:	Level 1		Level 2		Uncategorized		Total		Level 1		Level 2		Uncategorized		Total
Equity Securities	$	153.2	$	—	$	183.5	$	336.7	$	191.4	$	—	$	248.3	$	439.7
Fixed Income	18.2		40.2		141.1		199.5		49.7		45.2		125.5		220.4
Private Equity	—		—		70.9		70.9		—		—		58.7		58.7
Real Assets	71.2		—		36.2		107.4		90.0		—		31.0		121.0
Total	$	242.6	$	40.2	$	431.7	$	714.5	$	331.1	$	45.2	$	463.5	$	839.8
Add:  401(h) PBOP Assets (2)							255.6								298.5
Total PBOP Assets							$	970.1							$	1,138.3

(1)     Fixed Income investments classified as Level 1 as of December 31, 2022 include pending redemption settlements of $138 million.

(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
2022	$	59.9	$	7.7	$	12.8	$	4.8
2021	55.5		7.0		12.2		4.3
2020	49.4		6.6		11.8		4.1

Summary of Share Transactions

A summary of RSU transactions is as follows:

	RSUs (Units)	Weighted Average Grant-Date Fair Value
Outstanding as of December 31, 2021	594,623	$	65.70
Granted	218,005	$	85.96
Shares Issued	(174,633)	$	79.89
Forfeited	(8,261)	$	85.87
Outstanding as of December 31, 2022	629,734	$	68.52

A summary of performance share transactions is as follows:

	Performance Shares (Units)	Weighted Average Grant-Date Fair Value
Outstanding as of December 31, 2021	464,507	$	80.54
Granted	337,406	$	83.34
Shares Issued	(248,981)	$	68.96
Forfeited	(5,642)	$	85.28
Outstanding as of December 31, 2022	547,290	$	87.49

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)	2022		2021		2020
Compensation Expense	$	33.4	$	28.2	$	33.9
Future Income Tax Benefit	8.7		7.3		8.9

	For the Years Ended December 31,
	2022						2021						2020
(Millions of Dollars)	CL&P		NSTAR Electric		PSNH		CL&P		NSTAR Electric		PSNH		CL&P		NSTAR Electric		PSNH
Compensation Expense	$	10.0	$	10.7	$	3.6	$	8.8	$	9.0	$	3.0	$	10.9	$	11.3	$	3.6
Future Income Tax Benefit	2.6		2.8		0.9		2.3		2.3		0.8		2.9		3.0		1.0

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,
	2022		2021		2020
Actuarially-Determined Liability	$	43.4	$	42.8	$	45.7
Other Retirement Benefits Expense (1)	10.9		2.2		3.3

	As of and For the Years Ended December 31,
	2022						2021						2020
(Millions of Dollars)	CL&P		NSTAR Electric		PSNH		CL&P		NSTAR Electric		PSNH		CL&P		NSTAR Electric		PSNH
Actuarially-Determined Liability	$	0.2	$	0.1	$	1.3	$	0.2	$	0.1	$	1.5	$	0.2	$	0.1	$	1.7
Other Retirement Benefits Expense (1)	4.0		3.7		1.3		0.7		0.7		0.3		1.2		1.1		0.5

(1)    Other Retirement Benefits Expense in 2022 includes a one-time special retirement benefit payable of $9.2 million.