Components of Net Periodic Benefit Cost (Tables)

3 Months Ended

Mar. 31, 2024

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

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, 2024 and 2023, includes the following components:

	For the Three Months Ended March 31,
	Pension Plan(1)				RIM Plan				Post-retirement Plan				Split-Dollar Life Insurance
	2024		2023		2024		2023		2024		2023		2024		2023		Affected Line Item in the Consolidated Statements of Income
	(In thousands)
Service cost	$	1,212	$	1,199	$	61	$	69	$	54	$	54	$	57	$	69	Compensation and employee benefits
Interest cost	3,100		2,790		162		158		248		242		208		204		Other non-interest expense
Expected return on plan assets	(8,119)		(7,479)		—		—		—		—		—		—		Other non-interest expense
Amortization:
Prior service cost	—		—		—		—		—		—		14		14		Other non-interest expense
Net loss	512		—		28		14		—		—		—		—		Other non-interest expense
Net periodic (income) benefit cost	$	(3,295)	$	(3,490)	$	251	$	241	$	302	$	296	$	279	$	287
(1) Effective September 30, 2023, the RSI Pension Plan was merged into the Columbia Bank Pension Plan.

Net periodic (income) benefit cost for the Pension Plan and Post-retirement Plan for the three months ended March 31, 2024 and 2023, includes the following components:

	For the Three Months Ended March 31,
	Pension Plan (1)				Post-retirement Plan				Affected Line Item in the Consolidated Statements of Income
	2024		2023		2024		2023
	(In thousands)
Service cost	$	—	$	—	$	13	$	17	Compensation and employee benefits
Interest cost	—		76		31		27		Other non-interest expense
Expected return on plan assets	—		(122)		—		—		Other non-interest expense
Amortization:
Net (gain)	—		—		(5)		(15)		Other non-interest expense
Net periodic (income) benefit cost	$	—	$	(46)	$	39	$	29
(1) Effective September 30, 2023, the RSI Pension Plan was merged into the Columbia Bank Pension Plan.