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Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis by Level Within Fair Value Hierarchy (Parenthetical) (Details) - USD ($)
$ in Millions
Mar. 31, 2021
Dec. 31, 2020
Level 1 | Money Market Funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Restricted cash equivalents $ 15.6 $ 14.9