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Investments - Additional Information (Detail) - USD ($)
$ in Millions
Mar. 31, 2020
Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]    
Cash and cash equivalents $ 104.6 $ 99.2
Held-to-Maturity Securities [Member]    
Schedule of Held-to-maturity Securities [Line Items]    
Investments $ 26.5 $ 38.0