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Basis of Presentation - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]        
Research and development expenses $ 24.5 $ 23.1 $ 67.6 $ 64.4