v3.26.1
Components of Net Periodic Benefit Cost
 3 Months Ended
Mar. 31, 2026
Retirement Benefits [Abstract]  
Components of Net Periodic Benefit Cost Components of Net Periodic Benefit Cost
    Pension Plan, Retirement Income Maintenance Plan (the "RIM Plan") Post-retirement Plan, and Split-Dollar Life Insurance Plans

    The Company maintains a single employer, tax-qualified defined benefit pension plan (the "Pension Plan") which covers full-time employees hired prior to October 1, 2018, that satisfied the Pension Plan's eligibility requirements. The benefits are based on years of service and the employee's average compensation for the highest five consecutive years of employment.

The Company's policy is to fund at least the minimum contribution required by the Employee Retirement Income Security Act of 1974. GAAP requires an employer to: (a) recognize in its statement of financial position the over-funded or under-funded status of a defined benefit post-retirement plan measured as the difference between the fair value of plan assets and the benefit obligation; (b) measure a plan’s assets and its obligations that determine its funded status at the end of the employer’s fiscal year (with limited exceptions); and (c) recognize as a component of other comprehensive income (loss), net of tax, the actuarial gains and losses and the prior service costs and credits that arise during the period. The assets of the plan are primarily invested in fixed income and equity funds.

The Company also maintains a Retirement Income Maintenance Plan (the "RIM Plan") which is a non-qualified defined benefit plan which provides benefits to all employees of the Company if their benefits under the Pension Plan are limited by Internal Revenue Code Sections 415 and 401(a)(17).    

In addition, the Company provides certain health care and life insurance benefits to eligible retired employees under a Post-retirement Plan. The Company accrues the cost of retiree health care and other benefits during the employee's period of active service. Effective January 1, 2019, the Post-retirement Plan was closed to new hires.

The Company also provides life insurance benefits to eligible employees under an endorsement split-dollar life insurance program. The Company recognizes a liability for future benefits applicable to endorsement split-dollar life insurance arrangements that provide death benefits post-retirement. Through its mergers, the Company recognized additional liability for future benefits applicable to endorsement split-dollar life insurance arrangements that provide death benefits post-retirement under the programs of certain other previously acquired banks.
13.    Components of Net Periodic Benefit Cost

    Pension Plan, Retirement Income Maintenance Plan (the "RIM Plan") Post-retirement Plan, and Split-Dollar Life Insurance Plans (continued)

Net periodic (income) benefit cost for the Pension Plan, RIM Plan, Post-retirement Plan and Split-Dollar Life Insurance plan benefits for the three months ended March 31, 2026 and 2025, includes the following components:

 For the Three Months Ended March 31,
Pension PlanRIM PlanPost-retirement PlanSplit-Dollar Life Insurance
20262025202620252026202520262025 Affected Line Item in the Consolidated Statements of Income
(In thousands)
Service cost$887 $1,017 $44 $52 $50 $51 $47 $57 Compensation and employee benefits
Interest cost3,133 3,293 162 169 260 287 231 216 Other non-interest expense
Expected return on plan assets(9,508)(8,607)— — — — — — Other non-interest expense
Amortization:
Prior service cost— — — — — — 10 13 Other non-interest expense
Net loss— — — — — — — (22)Other non-interest expense
Net periodic (income) benefit cost$(5,488)$(4,297)$206 $221 $310 $338 $288 $264 
For the three months ended March 31, 2026 and 2025, no contributions were made to the Pension Plan. The net periodic (income) cost for pension benefits, other post-retirement and split-dollar life insurance benefits for the three months ended March 31, 2026 was calculated using the most recent available benefit valuations.