Employee Benefit Plans and Other Postretirement Benefits - Schedule Of Pension Plans With PBO And ABO In Excess Of Fair value Of Plan Assets (Details) - Pension and SERPA Benefits - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract]
PBO	$ 38,996	$ 58,804
Fair value of plan assets	0	0
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
ABO	30,598	44,232
Fair value of plan assets	$ 0	$ 0