Postretirement Benefits

6 Months Ended

Jun. 30, 2021

Retirement Benefits [Abstract]

Postretirement Benefits

Postretirement Benefits

Pension plans

Our pension plans consist of a noncontributory defined benefit pension plan covering substantially all employees and an unfunded supplemental employee retirement plan for certain members of executive and senior management. Although we are the sponsor of these postretirement plans and record the funded status of these plans, the Exchange and its subsidiaries reimburse us for approximately 58% of the annual benefit expense of these plans, which represents pension benefits for employees performing administrative services and their allocated share of costs for employees in departments that support the administrative functions.

The cost of our pension plans are as follows:

	Three months ended June 30,				Six months ended June 30,
(in thousands)	2021		2020		2021		2020
Service cost for benefits earned	$	13,260	$	10,874	$	26,520	$	21,747
Interest cost on benefits obligation	9,206		9,394		18,412		18,789
Expected return on plan assets	(12,568)		(12,353)		(25,137)		(24,706)
Prior service cost amortization	357		335		714		671
Net actuarial loss amortization	4,026		3,031		8,053		6,062
Pension plan cost (1)	$	14,281	$	11,281	$	28,562	$	22,563

(1)The components of pension plan costs other than the service cost component are included in the line item "Other expense" in the Statements of Operations after reimbursements from the Exchange and its subsidiaries.