Pension Plans (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
The excess plan
Pension plans
Fair values of pension assets	$ 1,197,000	$ 1,182,000

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant