Annual report pursuant to Section 13 and 15(d)

Nature of Operations And Accounting Policies (Summary of Contract Liabilities) (Details)

v3.20.4
Nature of Operations And Accounting Policies (Summary of Contract Liabilities) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Change in Contract with Customer, Liability [Roll Forward]    
Balance at beginning of period $ 794 $ 968
Previously deferred revenues recognized upon completion of performance obligations during the period (794) (968)
Net contract liabilities arising during the period 596 794
Balance at end of period $ 596 $ 794