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Employee Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Schedule of Target and Tactical Allocation of Plan Assets

The following table presents our target asset allocation permitted range along with the actual asset allocation as of December 31, 2023 and 2022:

			Permitted												Actual Allocation
Asset Class			Range												2023						2022
Return Enhancement			35			–			60%						48		%				48		%
Risk Management			40			–			80%						51						51
Alternatives			0			–			20%						1						1
Total															100		%				100		%

Schedule of Allocation of Plan Assets

The following presents the fair value inputs classified within the fair value hierarchy used to measure Pension Plan assets at December 31, 2023 and 2022 and assets measured using the net asset value (NAV) practical expedient:

(in thousands)			Level 1						Level 2						Level 3						NAV						Total
December 31, 2023
Equity Funds			$	127,159					$	—					$	—					$	—					$	127,159
Fixed Income Funds			167,604						—						—						—						167,604
Hybrid Funds			10,980						—						—						—						10,980
U.S. Treasury Securities			23,218						—						—						—						23,218
SEI Energy Debt Collective Fund			—						—						—						1,518						1,518
Total			328,961						—						—						1,518						330,479
December 31, 2022
Equity Funds			124,327						—						—						—						124,327
Fixed Income Funds			156,424						—						—						—						156,424
Hybrid Funds			9,756						—						—						—						9,756
U.S. Treasury Securities			19,587						—						—						—						19,587
SEI Energy Debt Collective Fund			—						—						—						3,703						3,703
Total			$	310,094					$	—					$	—					$	3,703					$	313,797

Schedule of Changes in Projected Benefit Obligations and Changes in Plan Assets

The following table provides a reconciliation of the changes in the fair value of plan assets and the actuarially computed benefit obligation for the years ended December 31, 2023 and 2022 and the funded status of the plans as of December 31, 2023 and 2022:

			Pension Benefits (Pension Plan)												Pension Benefits (ESSRP)												Postretirement Benefits
(in thousands)			2023						2022						2023						2022						2023						2022
Change in Fair Value of Plan Assets:
Fair Value of Plan Assets at January 1			$	313,797					$	387,212					$	—					$	—					$	—					$	—
Actual Return on Plan Assets			34,196						(76,485)						—						—						—						—
Company Contributions			—						20,000						2,197						2,205						3,167						2,294
Benefit Payments			(17,514)						(16,930)						(2,197)						(2,205)						(8,900)						(8,173)
Participant Premium Payments			—						—						—						—						5,733						5,879
Fair Value of Plan Assets at December 31			330,479						313,797						—						—						—						—
Change in Benefit Obligation:
Benefit Obligation at January 1			308,055						416,697						35,624						46,840						49,947						69,311
Service Cost			3,698						6,576						72						195						565						1,338
Interest Cost			16,436						12,344						1,889						1,341						2,416						2,041
Benefit Payments			(17,514)						(16,930)						(2,197)						(2,205)						(8,900)						(8,172)
Participant Premium Payments			—						—						—						—						5,733						5,879
Plan Amendments			—						—						—						—						(17,493)						—
Actuarial (Gain) Loss			8,126						(110,632)						392						(10,547)						(2,123)						(20,450)
Benefit Obligation at December 31			318,801						308,055						35,780						35,624						30,145						49,947
Funded Status			$	11,678					$	5,742					$	(35,780)					$	(35,624)					$	(30,145)					$	(49,947)
Amounts Recognized in Consolidated Balance Sheets at December 31:
Noncurrent Assets			$	11,678					$	5,742					$	—					$	—					$	—					$	—
Current Liabilities			—						—						(2,679)						(2,414)						(2,469)						(2,970)
Noncurrent Liabilities and Deferred Credits			—						—						(33,101)						(33,210)						(27,676)						(46,977)
Net Asset (Liability)			$	11,678					$	5,742					$	(35,780)					$	(35,624)					$	(30,145)					$	(49,947)

Schedule of Assumptions Used in Calculating Net Periodic Benefit Cost

The following assumptions were used to determine benefit obligations as of December 31, 2023 and 2022:

			Pension Benefits (Pension Plan)												Pension Benefits (ESSRP)												Postretirement Benefits
			2023						2022						2023						2022						2023						2022
Discount Rate			5.57		%				5.51		%				5.53		%				5.51		%				5.53		%				5.52		%
Long-Term Rate of Compensation Increase			n/a						n/a						3.00		%				3.00		%				n/a						n/a
Participants up to Age 39(1)			4.50		%				4.50		%				n/a						n/a						n/a						n/a
Participants Ages 40 to 49(2)			4.50		%				3.50		%				n/a						n/a						n/a						n/a
Participants Age 50 and Older(3)			3.75		%				2.75		%				n/a						n/a						n/a						n/a
Healthcare Cost Immediate Trend Rate			n/a						n/a						n/a						n/a						6.97		%				7.50		%
Healthcare Cost Ultimate Trend Rate			n/a						n/a						n/a						n/a						4.00		%				4.00		%
Year the Rate Reaches the Ultimate Trend Rate			n/a						n/a						n/a						n/a						2048						2048
(1) Amount reflects rate of compensation increases for both union and non-union employees.
(2) Amount reflects rate of compensation increases for union employees. The rate of compensation increases for non-union employees is 3.50%.
(3) Amount reflects rate of compensation increases for union employees. The rate of compensation increases for non-union employees is 3.00%.

The following assumptions were used to determine net periodic benefit cost for the years ended December 31, 2023, 2022 and 2021:

			Pension Benefits (Pension Plan)																		Pension Benefits (ESSRP)																		Postretirement Benefits
			2023						2022						2021						2023						2022						2021						2023						2022						2021
Discount Rate			5.51		%				3.03		%				2.78		%				5.51		%				2.93		%				2.61		%				5.52		%				3.01		%				2.75		%
Long-Term Rate of Return on Plan Assets			7.00		%				6.30		%				6.51		%				n/a						n/a						n/a						n/a						n/a						n/a
Long-Term Rate of Compensation Increase			n/a						n/a						n/a						3.00		%				3.00		%				3.00		%				n/a						n/a						n/a
Participants to Age 39			4.50		%				4.50		%				4.50		%				n/a						n/a						n/a						n/a						n/a						n/a
Participants Ages 40 to 49			3.50		%				3.50		%				3.50		%				n/a						n/a						n/a						n/a						n/a						n/a
Participants Age 50 and Older			2.75		%				2.75		%				2.75		%				n/a						n/a						n/a						n/a						n/a						n/a

Schedule of Net Benefit Costs

The following table lists the components of net periodic benefit cost of our defined benefit pension plans and other postretirement benefits for the years ended December 31, 2023, 2022 and 2021:

			Pension Benefits (Pension Plan)																		Pension Benefits (ESSRP)																		Postretirement Benefits
(in thousands)			2023						2022						2021						2023						2022						2021						2023						2022						2021
Service Cost			$	3,698					$	6,576					$	7,462					$	72					$	195					$	187					$	565					$	1,338					$	1,722
Interest Cost			16,436						12,344						11,660						1,889						1,341						1,228						2,416						2,041						1,891
Expected Return on Assets			(25,914)						(23,684)						(22,359)						—						—						—						—						—						—
Amortization of Prior Service Cost			—						—						—						—						—						—						(6,649)						(5,733)						(5,733)
Amortization of Net Actuarial Loss			—						7,865						10,914						—						567						620						—						3,063						3,774
Net Periodic Benefit Cost			$	(5,780)					$	3,101					$	7,677					$	1,961					$	2,103					$	2,035					$	(3,668)					$	709					$	1,654

The following table includes the impact of regulation on the recognition of periodic benefit cost arising from pension and other postretirement benefits for the years ended December 31, 2023, 2022 and 2021:

(in thousands)			2023						2022						2021
Net Periodic Benefit Cost			$	(7,487)					$	5,913					$	11,366
Net Amount Amortized Due to the Effect of Regulation			1,225						1,121						21
Net Periodic Benefit Cost Recognized			$	(6,262)					$	7,034					$	11,387

Schedule of Amounts Recognized in Balance Sheet

The following table presents the amounts not yet recognized as components of net periodic benefit cost as of December 31, 2023 and 2022:

			Pension Benefits (Pension Plan)												Pension Benefits (ESSRP)												Postretirement Benefits
(in thousands)			2023						2022						2023						2022						2023						2022
Regulatory Assets (Liabilities):
Unrecognized Prior Service Cost			$	—					$	—					$	—					$	—					$	(18,845)					$	(8,400)
Unrecognized Actuarial Loss			85,227						85,367						1,061						979						1,759						3,993
Net Regulatory Assets (Liabilities)			85,227						85,367						1,061						979						(17,086)						(4,407)
Accumulated Other Comprehensive Income (Loss):
Unrecognized Prior Service Cost			—						—						—						—						498						99
Unrecognized Actuarial Gain (Loss)			1,994						1,978						(1,403)						(1,093)						707						818
Total Accumulated Other Comprehensive Income (Loss)			$	1,994					$	1,978					$	(1,403)					$	(1,093)					$	1,205					$	917

Schedule of Expected Benefit Payments

The following reflects anticipated benefit payments to be paid in each of the next five years and in the aggregate for the five year period thereafter under our pension plans and postretirement healthcare plan:

(in thousands)			2024						2025						2026						2027						2028						2029-2033
Projected Pension Plan Benefit Payments			$	18,851					$	19,274					$	19,828					$	20,318					$	20,882					$	110,291
Projected ESSRP Benefit Payments			2,747						2,697						2,823						2,994						2,938						14,437
Projected Postretirement Benefit Payments			2,469						2,497						2,544						2,547						2,476						12,045
Total			$	24,067					$	24,468					$	25,195					$	25,859					$	26,296					$	136,773

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