Retirement Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2021

Compensation And Retirement Disclosure [Abstract]

Changes in Benefit Obligations and Plan Assets

The following tables detail the changes in the benefit obligations and plan assets of the defined benefit plans for the years ended December 31, 2021 and 2020, as well as the funded status of the plans at each year end and the amounts recognized in the Company’s consolidated balance sheets. The Company uses a December 31 measurement date for all defined benefit pension plans and other postretirement benefit plans.

	2021			2020			2021			2020
(in thousands)	Pension Benefits						Other Post- Retirement Benefits
Change in benefit obligation
Benefit obligation at beginning of year	$	660,309		$	581,866		$	18,330		$	16,713
Service cost		11,616			12,898			93			105
Interest cost		13,476			16,207			348			484
Plan participants' contributions		—			—			778			538
Net actuarial gain (loss)		(16,000	)		70,777			(1,506	)		1,910
Special termination benefits		16,052			—			4,173			—
Benefits paid		(38,621	)		(21,439	)		(1,934	)		(1,420	)
Benefit obligation, end of year		646,832			660,309			20,282			18,330
Change in plan assets
Fair value of plan assets at beginning of year		815,304			752,138			—			—
Actual return on plan assets		83,939			84,810			—			—
Employer contributions		1,181			1,178			1,156			882
Plan participants' contributions		—			—			778			538
Benefit payments		(38,621	)		(21,439	)		(1,934	)		(1,420	)
Expenses		(1,920	)		(1,383	)		—			—
Fair value of plan assets, end of year		859,883			815,304			—			—
Funded status at end of year - net asset (liability)	$	213,051		$	154,995		$	(20,282	)	$	(18,330	)
Amounts recognized in accumulated other    comprehensive loss
Unrecognized loss at beginning of year	$	164,770		$	136,252		$	(2,804	)	$	(5,369	)
Net actuarial loss (gain)		(56,649	)		28,518			(777	)		2,565
Unrecognized gain (loss) at end of year	$	108,121		$	164,770		$	(3,581	)	$	(2,804	)
Projected benefit obligation	$	646,832		$	660,309
Accumulated benefit obligation		607,408			624,999
Fair value of plan assets		859,883			815,304

Components of Net Periodic Benefits Cost

The following table shows net periodic benefit cost included in expense and the changes in the amounts recognized in AOCI during 2021, 2020, and 2019.

	Years Ended December 31,
	2021				2020				2019				2021				2020				2019
($ in thousands)	Pension Benefits												Other Post-Retirement Benefits
Net periodic benefit cost
Service cost	$		11,616		$		12,898		$		10,981		$		93		$		105		$		95
Interest cost			13,476				16,207				18,843				348				484				621
Expected return on plan assets			(46,654	)			(48,191	)			(45,199	)			—				—				—
Special termination benefits			16,052				—				—				4,173
Amortization of net (gain) loss/ prior service cost			5,284				7,021				10,087				(729	)			(653	)			(913	)
Net periodic benefit cost/benefit			(226	)			(12,065	)			(5,288	)			3,885				(64	)			(197	)
Other changes in plan assets and benefit    obligations recognized in other    comprehensive income, before taxes
Net (loss) gain recognized during the year			(5,284	)			(7,021	)			(10,087	)			729				653				913
Net actuarial loss (gain)			(51,365	)			35,539				(3,131	)			(1,506	)			1,912				733
Total recognized in other comprehensive    Income/loss			(56,649	)			28,518				(13,218	)			(777	)			2,565				1,646
Total recognized in net periodic benefit    cost and other comprehensive income/loss	$		(56,875	)	$		16,453		$		(18,506	)	$		3,108		$		2,501		$		1,449
Discount rate for benefit obligations			2.77	%			2.40	%			3.14	%			2.32	%			2.31	%			3.11	%
Discount rate for net periodic benefit cost			2.40	%			3.14	%			4.14	%			2.31	%			3.11	%			4.10	%
Expected long-term return on plan assets			5.75	%			6.50	%			7.25	%		n/a				n/a				n/a
Rate of compensation increase		scaled **				scaled *				scaled *				n/a				n/a				n/a

* Graded scale, declining from 7.25% at age 20 to 2.25% at age 60

** Graded scale, declining from 7.25% at age 20 to 2.25% at age 65

Expected Plan Benefit Payments

The following table presents expected plan benefit payments over the ten years succeeding December 31, 2021:

(in thousands)	Pension		Post-Retirement		Total
2022	$	25,683	$	1,950	$	27,633
2023		26,386		1,889		28,275
2024		27,566		1,555		29,121
2025		28,945		1,251		30,196
2026		30,336		997		31,333
2027-2031		168,868		4,680		173,548
.	$	307,784	$	12,322	$	320,106

Fair Values of Pension Plan Assets

For all investments, the plan attempts to use quoted market prices of identical assets on active exchanges, or Level 1 measurements. Where such quoted market prices are not available, the plan will use quoted prices for similar instruments or discounted cash flows to estimate the value, reported as Level 2

	December 31, 2021
Fair Value Measurements by Asset Category / Fund		Level 1			Level 2			Level 3		Total
(in thousands)
Cash and equivalents	$		21,280	$		—	$		—	$	21,280
Total cash and cash equivalents			21,280			—			—		21,280
Fixed income securities			29,687			40,254			—		69,941
Mutual fund-fixed income			20,428			—			—		20,428
Exchange Traded Fund (ETF)-Fixed income			4,049			—			—		4,049
Total fixed income			54,164			40,254			—		94,418
Domestic and foreign stock			109,610			—			—		109,610
Mutual funds-equity			270,863			—			—		270,863
Total equity			380,473						—		380,473
Total assets at fair value			455,917			40,254			—		496,171
Common trust funds (fixed income)			—			—			—		294,112
Common trust fund (real assets)			—			—			—		69,600
Total	$		455,917	$		40,254	$		—	$	859,883

	December 31, 2020
Fair Value Measurements by Asset Category / Fund		Level 1			Level 2			Level 3			Total
(in thousands)
Cash and equivalents	$		3,778	$		—	$		—	$		3,778
Total cash and cash equivalents			3,778			—			—			3,778
Fixed income securities			29,527			43,076			—			72,603
Mutual fund-fixed income			22,087			—			—			22,087
Exchange Traded Fund (ETF)-Fixed income			3,750			—			—			3,750
Total fixed income			55,364			43,076			—			98,440
Domestic and foreign stock			97,966			—			—			97,966
Mutual funds-equity			260,019			—			—			260,019
Total equity			357,985						—			357,985
Total assets at fair value			417,127			43,076			—			460,203
Common trust funds (fixed income)			—			—			—			298,694
Common trust fund (real assets)			—			—			—			56,407
Total	$		417,127	$		43,076	$		—	$		815,304

Percentage and Target Allocations

The following table presents the percentage allocation of the plan assets by asset category and corresponding target allocations at December 31, 2021 and 2020.

	Plan Assets						Target Allocation
	at December 31,						at December 31,
Asset category	2021			2020			2021	2020
Cash and equivalents		3	%		0	%	0 - 5%	0 - 5%
Fixed income securities		45			49		41-47%	41-57%
Equity securities		44			44		35-51%	35 - 51%
Real assets		8			7		0-12%	0 - 12%
		100	%		100	%