Employee Benefits - Schedule of Reconciliation of Changes in Benefit Obligation and Fair value of Plan Assets As Well As the Funded Status Recognized in the Consolidated Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Reconciliation of changes in benefit obligations
Benefit Obligation at Beginning of Year	$ 110,637	$ 102,662
Service Cost	0	0	$ 0
Interest Cost	3,627	4,401	4,193
Actuarial Losses (Gains)	10,364	10,359
Employer Benefits Paid	(6,981)	(6,785)
Benefit Obligation at End of Year	117,647	110,637	102,662
Reconciliation of changes in fair value of plan assets
Fair Value of Plan Assets at Beginning of Year	93,638	85,553
Actual Return on Plan Assets	10,764	14,400
Employer Contributions	469	470
Employer Benefits Paid	(6,981)	(6,785)
Fair Value of Plan Assets at End of Year	97,890	93,638	85,553
Funded Status at End of Year	(19,757)	(16,999)
Postretirement Benefits
Reconciliation of changes in benefit obligations
Benefit Obligation at Beginning of Year	27,571	23,452
Service Cost	578	455	457
Interest Cost	945	1,025	936
Actuarial Losses (Gains)	3,559	4,095
Employer Benefits Paid	(1,146)	(1,456)
Benefit Obligation at End of Year	31,507	27,571	$ 23,452
Reconciliation of changes in fair value of plan assets
Employer Contributions	1,146	1,456
Employer Benefits Paid	(1,146)	(1,456)
Funded Status at End of Year	$ (31,507)	$ (27,571)