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Significant Accounting Policies - Description of Business (Details) - segment
3 Months Ended 12 Months Ended
Dec. 31, 2020
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Dec. 31, 2020
Significant Accounting Policies          
Number of operating segments         1
Fiscal period duration (in days) 91 days 91 days 91 days 91 days