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Summary of Significant Accounting Policies - Financial Instruments and Concentration of Credit Risk (Details)
3 Months Ended
Mar. 31, 2020
USD ($)
item
Dec. 31, 2019
USD ($)
Financial Instruments and Concentration of Credit Risk    
Number of financial institutions in the U.S. in which cash and cash equivalents are primarily maintained | item 3  
Marketable securities held by entity | $ $ 0 $ 0