Employee Benefits (Tables)

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Net Periodic Benefit Cost

The components of the net periodic benefit cost for our pension and postretirement benefit plans are as follows:

	Pension Plan				Postretirement Benefit Plan
Three Months Ended March 31,	2021		2020		2021		2020
Net periodic benefit cost
Service cost	$	3,020	$	2,707	$	148	$	432
Interest cost	1,728		2,066		69		253
Expected return on plan assets	(4,202)		(3,385)		—		—
Amortization of prior service credit	(809)		—		(3,196)		(2,021)
Amortization of net loss	999		979		492		94
Special event plan closure	—		—		(20,177)		—
Net periodic benefit cost	$	736	$	2,367	$	(22,664)	$	(1,242)