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Employee Benefit Plans (Narrative) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Pension Plan [Member]    
Employee benefit plans    
Contribution made by the entity under the pension plan $ 53,000 $ 55,000
401 (k) Plan [Member]    
Employee benefit plans    
Matching contribution by employer as a percentage of the employee's deferral 100.00%  
Matching contribution by employer as a percentage of U.S. employee's qualifying compensation 6.00%  
Statutorily prescribed annual limit of contributions made by an employee before attaining age of 50 years $ 19,000  
Statutorily prescribed annual limit of contributions made by an employee after attaining age of 50 years $ 25,000  
Specified age limit of employees for calculation of statutorily prescribed annual limit of contribution 50 years  
Contribution made by the entity under the 401(k) Plan $ 54,000 $ 36,000