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Summary of Significant Accounting Policies - Patent Costs (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Dec. 31, 2020
Dec. 31, 2019
Accounting Policies [Abstract]        
Patent costs $ 0.2 $ 1.0 $ 2.1 $ 2.0