Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Schedule of Amounts Recognized in Balance Sheet

Changes in benefit obligation and plan assets and amounts recognized in the Consolidated Balance Sheets at December 31 were as follows:

	Pension Benefits				Other Postretirement Benefits
	2023		2022		2023		2022
Change in benefit obligation:	(In thousands)
Benefit obligation at beginning of year	$	278,286	$	367,134	$	40,315	$	53,981
Service cost	—		—		534		894
Interest cost	13,521		9,396		1,956		1,383
Plan participants' contributions	—		—		479		566
Actuarial loss/(gain)	5,395		(76,130)		(215)		(13,083)
Benefits paid	(21,616)		(22,114)		(3,479)		(3,426)
Benefit obligation at end of year	275,586		278,286		39,590		40,315
Change in net plan assets:
Fair value of plan assets at beginning of year	242,031		333,764		76,640		99,844
Actual return on plan assets	20,576		(69,619)		5,518		(20,419)
Employer contribution	7,567		—		76		75
Plan participants' contributions	—		—		479		566
Benefits paid	(21,616)		(22,114)		(3,479)		(3,426)
Fair value of net plan assets at end of year	248,558		242,031		79,234		76,640
Funded status - (under) over	$	(27,028)	$	(36,255)	$	39,644	$	36,325
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent assets - other	$	—	$	—	$	39,644	$	36,325
Noncurrent liabilities - other	27,028		36,255		—		—
Benefit obligation (liabilities) assets - net amount recognized	$	(27,028)	$	(36,255)	$	39,644	$	36,325
Amounts recognized in accumulated other comprehensive loss:
Actuarial loss (gain)	$	32,273	$	32,378	$	(3,515)	$	(2,923)
Prior service credit	—		—		(115)		(289)
Total	$	32,273	$	32,378	$	(3,630)	$	(3,212)
Amounts recognized in regulatory assets or liabilities:
Actuarial loss (gain)	$	140,232	$	141,207	$	(1,146)	$	(1,439)
Prior service credit	—		—		(2,619)		(3,796)
Total	$	140,232	$	141,207	$	(3,765)	$	(5,235)

Schedule of Accumulated and Projected Benefit Obligations

The pension plans all have accumulated benefit obligations in excess of plan assets. The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans at December 31 were as follows:

	2023		2022
	(In thousands)
Projected benefit obligation	$	275,586	$	278,286
Accumulated benefit obligation	$	275,586	$	278,286
Fair value of plan assets	$	248,558	$	242,031

The projected benefit obligation and accumulated benefit obligation for these plans at December 31 were as follows:

	2023		2022
	(In thousands)
Projected benefit obligation	$	57,033	$	58,683
Accumulated benefit obligation	$	57,033	$	58,683

Schedule of Net Benefit Costs

The components of net periodic benefit cost (credit), other than the service cost component, are included in other income on the Consolidated Statements of Income. Prior service credit is amortized on a straight-line basis over the average remaining service period of active participants. These components related to the Company's pension and other postretirement benefit plans for the years ended December 31 were as follows:

	Pension Benefits						Other Postretirement Benefits
	2023		2022		2021		2023		2022		2021
Components of net periodic benefit credit:	(In thousands)
Service cost	$	—	$	—	$	—	$	534	$	894	$	1,033
Interest cost	13,521		9,396		8,767		1,956		1,383		1,370
Expected return on assets	(17,194)		(17,482)		(17,548)		(5,361)		(5,277)		(5,079)
Amortization of prior service credit	—		—		—		(1,318)		(1,318)		(1,318)
Recognized net actuarial loss (gain)	3,093		5,826		7,046		(504)		(570)		(111)
Net periodic benefit credit, including amount capitalized	(580)		(2,260)		(1,735)		(4,693)		(4,888)		(4,105)
Less amount capitalized	—		—		—		107		175		150
Net periodic benefit cost credit	(580)		(2,260)		(1,735)		(4,800)		(5,063)		(4,255)
Other changes in plan assets and benefit obligations recognized in accumulated comprehensive loss:
Net (gain) loss	187		2,369		(265)		(604)		(4,141)		(2,811)
Amortization of actuarial (loss) gain	(292)		(1,310)		(1,286)		108		(281)		(135)
Amortization of prior service credit	—		—		—		78		125		100
Reclassification of postretirement liability adjustment from regulatory asset	—		5,343		—		—		(992)		—
Total recognized in accumulated other comprehensive loss	(105)		6,402		(1,551)		(418)		(5,289)		(2,846)
Other changes in plan assets and benefit obligations recognized in regulatory assets or liabilities:
Net (gain) loss	1,826		9,757		(5,116)		(107)		11,920		(6,292)
Amortization of actuarial (loss) gain	(2,801)		(5,373)		(6,731)		304		500		110
Amortization of prior service credit	—		—		—		1,273		1,273		1,298
Reclassification of postretirement liability adjustment from regulatory asset	—		(5,343)		—		—		992		—
Total recognized in regulatory assets or liabilities	(975)		(959)		(11,847)		1,470		14,685		(4,884)
Total recognized in net periodic benefit credit, accumulated other comprehensive loss and regulatory assets or liabilities	$	(1,660)	$	3,183	$	(15,133)	$	(3,748)	$	4,333	$	(11,985)

The components of net periodic benefit cost are included in other income on the Consolidated Statements of Income. These components related to the Company's nonqualified defined benefit plans for the years ended December 31 were as follows:

	2023		2022		2021
	(In thousands)
Components of net periodic benefit cost:
Interest cost	2,740		1,681		1,505
Recognized net actuarial loss	273		911		942
Net periodic benefit cost	$	3,013	$	2,592	$	2,447

Defined Benefit Plan, Assumptions

Weighted average assumptions used to determine benefit obligations at December 31 were as follows:

	Pension Benefits				Other Postretirement Benefits
	2023		2022		2023		2022
Discount rate	4.84	%	5.06	%	4.85	%	5.07	%
Expected return on plan assets	6.50	%	6.50	%	6.00	%	6.00	%

Weighted average assumptions used to determine net periodic benefit cost (credit) for the years ended December 31 were as follows:

	Pension Benefits				Other Postretirement Benefits
	2023		2022		2023		2022
Discount rate	5.06	%	2.64	%	5.07	%	2.65	%
Expected return on plan assets	6.50	%	6.00	%	6.00	%	5.50	%

Weighted average assumptions used at December 31 were as follows:

	2023		2022
Benefit obligation discount rate	4.73	%	4.97	%
Benefit obligation rate of compensation increase	N/A		N/A
Net periodic benefit cost discount rate	4.97	%	2.40	%
Net periodic benefit cost rate of compensation increase	N/A		N/A

Schedule of Health Care Cost Trend Rates

Health care rate assumptions for the Company's other postretirement benefit plans as of December 31 were as follows:

	2023		2022
Health care trend rate assumed for next year	6.5	%	6.5	%
Health care cost trend rate - ultimate	4.5	%	4.5	%
Year in which ultimate trend rate achieved	2033		2032

Schedule of Expected Benefit Payments

The following benefit payments, which reflect future service, as appropriate, and expected Medicare Part D subsidies at December 31, 2023, are as follows:

Years	Pension Benefits		Other Postretirement Benefits		Expected Medicare Part D Subsidy
			(In thousands)
2024	$	22,050	$	3,498	$	50
2025	21,980		3,473		44
2026	21,810		3,359		39
2027	21,660		3,265		35
2028	21,320		3,171		29
2029-2033	99,970		14,580		94

The amount of future benefit payments for the unfunded, nonqualified defined benefit plans at December 31, 2023, are expected to aggregate as follows:

	2024		2025		2026		2027		2028		2029-2033
	(In thousands)
Nonqualified benefits	$	5,584	$	5,726	$	5,795	$	5,807	$	5,481	$	21,962

Schedule of Allocation of Plan Assets

The fair value of the Company's pension plans' assets (excluding cash) by class were as follows:

	Fair Value Measurements  at December 31, 2023, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable  Inputs  (Level 3)		Balance at December 31, 2023
	(In thousands)
Assets:
Cash equivalents	$	—	$	7,197	$	—	$	7,197
Equity securities:
U.S. companies	(2)		—		—		(2)
Collective and mutual funds (a)	84,761		88,219		—		172,980
U.S. Government securities	30,162		33,141		—		63,303
Investments measured at net asset value (b)	—		—		—		5,080
Total assets measured at fair value	$	114,921	$	128,557	$	—	$	248,558

(a)Collective and mutual funds invest approximately 51 percent in corporate bonds, 15 percent in common stock of international companies, 11 percent in common stock of large-cap and mid-cap U.S. companies, 7 percent cash and cash equivalents, 7 percent in U.S. Government securities and 9 percent in other investments.

(b)In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets.

	Fair Value Measurements  at December 31, 2022, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable  Inputs  (Level 3)		Balance at December 31, 2022
	(In thousands)
Assets:
Cash equivalents	$	—	$	7,311	$	—	$	7,311
Equity securities:
U.S. companies	6,611		—		—		6,611
International companies	—		418		—		418
Collective and mutual funds (a)	108,343		29,863		—		138,206
Corporate bonds	—		72,809		—		72,809
Municipal bonds	—		5,283		—		5,283
U.S. Government securities	2,724		788		—		3,512
Pooled separate accounts (b)	—		2,904		—		2,904
Investments measured at net asset value (c)	—		—		—		4,977
Total assets measured at fair value	$	117,678	$	119,376	$	—	$	242,031

(a)Collective and mutual funds invest approximately 29 percent in corporate bonds, 24 percent in common stock of large-cap U.S. companies, 16 percent in common stock of international companies, 7 percent cash and cash equivalents, 7 percent in U.S. Government securities and 17 percent in other investments.

(b)Pooled separate accounts are invested 100 percent in cash and cash equivalents.

(c)In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets.

The fair value of the Company's other postretirement benefit plans' assets (excluding cash) by asset class were as follows:

	Fair Value Measurements  at December 31, 2023, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable  Inputs  (Level 3)		Balance at December 31, 2023
	(In thousands)
Assets:
Cash equivalents	$	—	$	4,562	$	—	$	4,562
Equity securities:
U.S. companies	2,369		—		—		2,369
Insurance contract (a)	—		72,303		—		72,303
Total assets measured at fair value	$	2,369	$	76,865	$	—	$	79,234

(a)The insurance contract invests approximately 60 percent in corporate bonds, 16 percent in common stock of large-cap U.S. companies, 15 percent in U.S. Government securities, 5 percent in common stock of small-cap U.S. companies and 4 percent in other investments.

	Fair Value Measurements  at December 31, 2022, Using
	Quoted Prices in Active Markets for Identical Assets  (Level 1)		Significant Other Observable Inputs  (Level 2)		Significant Unobservable  Inputs  (Level 3)		Balance at December 31, 2022
	(In thousands)
Assets:
Cash equivalents	$	—	$	4,213	$	—	$	4,213
Equity securities:
U.S. companies	2,583		—		—		2,583
Collective and mutual funds (a)	5		5		—		10
Insurance contract (b)	—		69,834		—		69,834
Total assets measured at fair value	$	2,588	$	74,052	$	—	$	76,640

(a)Collective and mutual funds invest approximately 29 percent in corporate bonds, 24 percent in common stock of large-cap U.S. companies, 16 percent in common stock of international companies, 7 percent in cash and cash equivalents, 7 percent in U.S. Government securities and 17 percent in other investments.

(b)The insurance contract invests approximately 69 percent in corporate bonds, 14 percent in common stock of large-cap U.S. companies, 13 percent in U.S. Government securities and 4 percent in common stock of small-cap U.S. companies.

The amount of investments that the Company anticipates using to satisfy obligations under these plans at December 31 was as follows:

	2023		2022
	(In thousands)
Investments
Insurance contracts*	$	66,283	$	77,958
Life insurance**	31,303		31,214
Other	6,409		4,913
Total investments	$	103,995	$	114,085

*For more information on the insurance contracts, see Note 9.

**Investments of life insurance are carried on plan participants (payable upon the employee's death).

Schedule of Multiemployer Plans

	EIN/Pension Plan Number	Pension Protection Act Zone Status		FIP/RP Status Pending/Implemented	Contributions						Surcharge Imposed	Expiration Date of Collective Bargaining Agreement
Pension Fund		2023	2022		2023		2022		2021
					(In thousands)
Edison Pension Plan	936061681-001	Green	Green	No	$	16,957	$	18,750	$	18,331	No	12/31/2026
IBEW Local 212 Pension Trust	316127280-001	Green as of 4/30/2022	Green as of 4/30/2021	No	1,350		1,622		1,733		No	6/1/2025
IBEW Local 357 Pension Plan A	886023284-001	Green	Green	No	18,936		12,876		6,485		No	5/31/2024
IBEW Local 82 Pension Plan	316127268-001	Green as of 6/30/2023	Green as of 6/30/2022	No	2,149		1,854		1,353		No	12/6/2026
IBEW Local 683 Pension Fund Pension Plan	341442087-001	Green	Green	No	3,986		3,362		1,238		No	5/26/2024
Idaho Plumbers and Pipefitters Pension Plan	826010346-001	Green as of 5/31/2023	Green as of 5/31/2022	No	1,690		1,613		1,528		No	3/31/2027
National Electrical Benefit Fund	530181657-001	Green	Green	No	19,040		18,060		14,361		No	12/31/2023- 12/27/2027	*
Pension and Retirement Plan of Plumbers and Pipefitters Local 525	886003864-001	Green as of 6/30/2022	Green as of 6/30/2022	No	8,020		6,304		4,345		No	9/30/2024
Sheet Metal Workers Pension Plan of Southern CA, AZ, and NV	956052257-001	Green	Green	No	3,631		3,400		2,615		No	6/30/2024
Other funds					21,289		20,437		17,930
Total contributions					$	97,048	$	88,278	$	69,919

*Plan includes contributions required by collective bargaining agreements which have expired but contain provisions automatically renewing their terms in the absence of a subsequent negotiated agreement.

The Company was listed in the plans' Forms 5500 as providing more than 5 percent of the total contributions for the following plans and plan years:

Pension Fund	Year Contributions to Plan Exceeded More Than 5 Percent of Total Contributions (as of December 31 of the Plan's Year-End)
Edison Pension Plan	2022 and 2021
Eighth District Electrical Pension Fund	2022
Electrical Workers Local No. 26 Pension Fund	2022
IBEW Local 82 Pension Plan	2022 and 2021
IBEW Local 124 Pension Trust Fund	2022 and 2021
IBEW Local 212 Pension Trust Fund	2022 and 2021
IBEW Local 357 Pension Plan A	2021
IBEW Local 648 Pension Plan	2022 and 2021
IBEW Local 683 Pension Fund Pension Plan	2022 and 2021
Idaho Plumbers and Pipefitters Pension Plan	2022 and 2021
National Electrical Benefit Fund	2022
Pension and Retirement Plan of Plumbers and Pipefitters Local 525	2022 and 2021
Sheet Metal Workers Pension Plan of Southern CA, AZ, and NV	2022
Western States Insulators and Allied Workers' Pension Plan	2022