Employee Benefit Plans - Schedule of amounts recognized in the balances sheets (Details) - Other Postretirement Benefit Plans, Defined Benefit - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Amounts recognized in the balances sheets
Long-term liabilities - retirement benefits and other	$ 2,529,000	$ 2,126,000
Accumulated other comprehensive loss, before income taxes:
Net actuarial loss	$ 1,716,000	$ 1,419,000

Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant