Retirement Plans and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2022

Retirement Benefits [Abstract]

Summary of Retirement Plans and Other Postretirement Benefits

Information with respect to the Retirement Plans and Other Postretirement Benefits follows:

	Retirement Plans				Other Postretirement Benefits
(Dollars in thousands)	2022		2021		2022		2021
Change in benefit obligation:
Benefit obligation at beginning of year	$	57,698	$	59,431	$	3,536	$	3,540
Service cost	558		567		123		143
Interest cost	1,573		1,431		96		85
Actuarial gain	(9,776)		(1,043)		(1,136)		(124)
Benefits paid	(2,774)		(2,688)		(95)		(108)
Benefit obligation at end of year	$	47,279	$	57,698	$	2,524	$	3,536
Change in plan assets:
Fair value of plan assets at beginning of year	$	60,479	$	55,366	$	—	$	—
Actual (loss) return on plan assets	(8,463)		7,644		—		—
Benefits paid	(2,774)		(2,688)		(95)		(108)
Employer contribution and non-qualified benefit payments	157		157		95		108
Fair value of plan assets at end of year	$	49,399	$	60,479	$	—	$	—
Funded status	2,120		2,781		(2,524)		(3,536)
Unrecognized net actuarial loss (gain)	19,851		18,226		(371)		820
Net amount recognized	$	21,971	$	21,007	$	(2,895)	$	(2,716)

Components of Net Periodic Benefit Cost (Income)

Components of net periodic benefit (income) cost were as follows: 

	Retirement Plans						Other Postretirement Benefits
(Dollars in thousands)	2022		2021		2020		2022		2021		2020
Service cost	$	558	$	567	$	477	$	123	$	143	$	109
Interest cost	1,573		1,431		1,692		96		85		96
Expected loss on plan assets	(3,756)		(3,656)		(3,291)		—		—		—
Amortization of net actuarial loss	817		1,269		1,176		56		47		26
Net periodic benefit (income) cost	$	(808)	$	(389)	$	54	$	275	$	275	$	231

Expected Amortization Expense

(Dollars in thousands)	Retirement Plans		Other Postretirement Benefits
Expected amortization expense for 2023:
Amortization (accretion) of net actuarial loss (gain)	$	1,000	$	(15)

Summary of Benefit Payments Expected to be Paid

The following benefits payments, which reflect expected future service, as appropriate, are expected to be paid:

(Dollars in thousands)	Retirement Plans		Other Postretirement Benefits
For the fiscal year ending:
2023	$	3,112	$	130
2024	3,203		135
2025	3,210		137
2026	3,267		142
2027	3,279		150
Years 2028-2032	16,447		830
Total	$	32,518	$	1,524

Weighted-Average Assumptions Used to Determine Benefit Obligations

Weighted-average assumptions used to determine benefit obligations at December 31, 2022 and 2021 were as follows:

	Retirement Plans				Other Postretirement Benefits
	2022		2021		2022		2021
Assumed discount rate	5.2	%	2.8	%	5.2	%	2.8	%
Assumed salary increase rate	3%-6%		3%-6%		—		—

The benefit obligation for all plans at December 31, 2022 was based on the Pri-2012 White Collar Dataset Mortality Table with scale MP-2021 fully generational published by the Society of Actuaries. The discount rate is based on matching the Plan's projected cash flows to the spot rates in FTSE Pension Above Median Double-A Curve as of the disclosure date. The assumed salary increase considers available service years from the valuation date through the participant's normal retirement date.

Weighted-average assumptions used to determine net periodic costs for the years ended December 31, 2022 and 2021 were as follows:

	Retirement Plans				Other Postretirement Benefits
	2022		2021		2022		2021
Assumed discount rate	2.8	%	2.4	%	2.8	%	2.4	%
Assumed long-term rate of investment return	6.5	%	6.5	%	—		—
Assumed salary increase rate	3%-6%		3%-6%		—		—
Assumed cash balance interest crediting rate	2.6	%	2.0	%	—		—

Summary of Corporation's Pension Plan Asset Allocation

The Corporation's pension plan asset allocation at December 31, 2022 and 2021, by asset category was as follows:

	Percentage of Plan Assets at December 31,
	2022		2021
Asset Category:
Equity securities	62	%	64	%
Debt securities	36		34
Other	2		2
Total	100	%	100	%

Major Categories of Assets in Corporation's Pension Plan

The major categories of assets in the Corporation's pension plan at year-end are presented in the following table. Assets are segregated by the level of the valuation inputs within the fair value hierarchy described in Note 19, "Fair Value Disclosures."

	Fair Value Measurements at December 31,
(Dollars in thousands)	2022		2021
Level 1:
Mutual funds	$	32,982	$	41,951
Short-term investments	1,187		1,619
Level 2:
U.S. government obligations	6,629		7,050
Corporate bonds	5,427		6,536
Certificates of deposit	3,174		3,323
Total fair value of plan assets	$	49,399	$	60,479