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Cash Equivalents and Marketable Securities - Additional Information (Details) - U.S. government and agency securities
$ in Millions
Dec. 31, 2019
USD ($)
Security
Dec. 31, 2018
USD ($)
Security
Cash Equivalents And Marketable Securities [Line Items]    
Fair value of debt securities in an unrealized loss position | $ $ 13.0 $ 45.6
Number of securities in a significant unrealized loss position | Security 0 0