Retirement plans (Tables)

12 Months Ended

Dec. 31, 2024

Retirement Benefits [Abstract]

Schedule of Pension Costs

Pension costs, which primarily include costs for our qualified TRP and non-qualified SERP, are presented in the following table (in thousands):

	2024			2023			2022
Interest cost on benefit obligation	$	22,756		$	24,183		$	16,830
Expected return on plan assets		(22,066	)		(20,940	)		(19,502	)
Amortization of prior service cost		90			90			90
Amortization of actuarial loss		5,942			6,059			4,583
Pension settlement charge		10,316			—			300
Expense for (income from) company-sponsored retirement plans	$	17,038		$	9,392		$	2,301

Schedule of Changes in Projected Benefit Obligations

The following table provides a reconciliation of pension benefit obligations (on a projected benefit obligation measurement basis), plan assets and funded status of company-sponsored retirement plans, along with the related amounts that are recognized in the Consolidated Balance Sheets (in thousands).

	Dec. 31,
	2024			2023
Change in benefit obligations
Benefit obligations as of beginning of year	$	462,466		$	464,309
Interest cost		22,756			24,183
Actuarial (gain) loss		(14,400	)		9,443
Benefits paid		(32,666	)		(35,469	)
Pension settlements (1)		(28,334	)		—
Benefit obligations as of end of year	$	409,822		$	462,466
Change in plan assets
Fair value of plan assets as of beginning of year	$	386,108		$	385,005
Actual gains experienced by plan assets		5,270			32,739
Employer contributions		7,524			3,833
Benefits paid		(32,666	)		(35,469	)
Pension settlements (1)		(28,334	)		—
Fair value of plan assets as of end of year	$	337,902		$	386,108
Funded status as of end of year	$	(71,920	)	$	(76,358	)
Amounts recognized in Consolidated Balance Sheets
Accrued liabilities other—current	$	(5,964	)	$	(5,875	)
Pension liabilities—non-current	$	(65,956	)	$	(70,483	)

(1) Settlements represent lump sum benefit payments to certain TRP participants. When aggregate lump sums exceed the settlement threshold, pension settlement charges are incurred, and the lump sum payments prompting the charge are shown on a separate line from other benefit payments.

Schedule of Net Funded Status

The funded status (on a projected benefit obligation basis) of our principal retirement plans as of December 31, 2024, is as follows (in thousands):

	Fair Value of Plan Assets		Benefit Obligation		Funded Status
TRP	$	337,902	$	365,381	$	(27,479	)
SERP (1)		—		44,162		(44,162	)
All other		—		279		(279	)
Total	$	337,902	$	409,822	$	(71,920	)

(1) The SERP is an unfunded, unsecured liability.

Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets

The following table presents information for our retirement plans for which accumulated benefit obligation exceed assets (in thousands):

	Dec. 31,
	2024		2023
Accumulated benefit obligation	$	409,822	$	462,466
Fair value of plan assets	$	337,902	$	386,108

Schedule of Benefit Obligations in Excess of Fair Value of Plan Assets

The following table presents information for our retirement plans for which projected benefit obligations exceed assets (in thousands):

	Dec. 31,
	2024		2023
Projected benefit obligation	$	409,822	$	462,466
Fair value of plan assets	$	337,902	$	386,108

Schedule of Net Periodic Benefit Cost Not Yet Recognized

The following table summarizes the pre-tax amounts recorded in accumulated other comprehensive loss that have not yet been recognized as a component of pension expense (in thousands):

	Dec. 31,
	2024			2023
Net actuarial losses	$	(145,225	)	$	(159,086	)
Prior service cost		(1,346	)		(1,436	)
Amounts in accumulated other comprehensive loss	$	(146,571	)	$	(160,522	)

Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss)

Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss), pre-tax, consist of the following (in thousands):

	2024			2023		2022
Current year net actuarial (loss)/gain	$	(2,392	)	$	2,356	$	(23,688	)
Amortization of actuarial loss		5,942			6,059		4,583
Amortization of previously deferred prior service costs		90			90		90
Pension settlement charge		10,316			—		300
Total	$	13,956		$	8,505	$	(18,715	)

Schedule of Assumptions Used

Pension costs: The following assumptions were used to determine net pension costs:

	2024	2023	2022
Discount rate	5.20%	5.50%	2.89%
Expected return on plan assets	6.00%	5.75%	3.75%

Schedule of Assumptions Used in Calculating Pension Benefit Obligations Table

The following assumptions were used to determine the year-end benefit obligations:

	Dec. 31,
	2024	2023
Discount rate	5.60%	5.20%

Schedule of Allocation of Plan Assets

The asset allocation for the TRP as of the end of 2024 and 2023, and target allocations for 2024, by asset category, are presented in the table below:

	Target Allocation	Actual allocation of Plan Assets
	2025	2024	2023
Equity securities	33%	20%	17%
Debt securities	67%	80%	83%
Total	100%	100%	100%

Schedule of Expected Benefit Payments

We estimate we will make the following benefit payments from either retirement plan assets or directly from our funds (in thousands):

Future Period	Cash Payments
2025	$	48,697
2026		41,456
2027		36,796
2028		36,465
2029		35,309
2030 through 2034	$	159,004