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Fair Value Measurements - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Transfers from level 1 to level 2 $ 0 $ 0
Transfers from level 2 to level 1 0 0
Transfers in or out of Level 3 0 0
Other current liabilities 9,987,000 $ 7,000,000
Merck, Sharp & Dohme Corp.    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Other current liabilities 7,000,000.0  
Merck, Sharp & Dohme Corp. | Fair Value, Inputs, Level 3    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Other current liabilities $ 6,900,000