Retirement Benefits

3 Months Ended

Mar. 31, 2021

Employee Benefit Plans [Abstract]

Employee Benefit Plans

14.  RETIREMENT BENEFITS

The Company maintains both qualified and non-qualified defined benefit pension plans for its U.S. employees employed prior to April 1, 2010. Generally, the Company computes the benefits based on average earnings over a period prescribed by the plans and credited length of service. The Company’s non-qualified defined benefit pension plan provided compensating pension benefits for participants whose benefits have been curtailed under the qualified plan due to Internal Revenue Code limitations. Effective January 1, 2018, participants of the Company’s non-qualified defined benefit pension plan may no longer accrue additional service benefits.

Net periodic benefit cost for U.S. employees included the following components for the periods indicated:

Pension Benefits	Three Months Ended
	March 31,
(Dollars in thousands)	2021		2020
Service cost	$	2,738	$	4,011
Interest cost		1,999		2,483
Expected return on plan assets		(5,580)		(5,197)
Amortization of net (income) loss		2,730		1,213
Net periodic benefit cost	$	1,887	$	2,510

Other Benefits	Three Months Ended
	March 31,
(Dollars in thousands)	2021		2020
Service cost	$	281	$	141
Interest cost		181		215
Amortization of prior service cost		(144)		(48)
Net periodic benefit cost	$	318	$	308
(Some amounts may not reconcile due to rounding.)

The service cost component of net periodic benefit costs is included within other underwriting expenses on the consolidated statement of operations and comprehensive income (loss). In accordance with ASU 2017-07, other staff compensation costs are also primarily recorded within this line item.

The Company did not make any contributions to the qualified pension benefit plan for the three months ended March 31, 2021 and 2020, respectively.