Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Marketable Available-for-Sale Securities (Detail)

v3.20.1
Summary of Significant Accounting Policies - Marketable Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
Mar. 31, 2020
Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]    
Estimated Fair Value $ 119,438 $ 166,076
Cash and Cash Equivalents [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 53,147 18,597
Estimated Fair Value 53,147 18,597
Cash and Cash Equivalents [Member] | Money Market Funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 53,147 18,597
Estimated Fair Value 53,147 18,597
Short-term Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 119,569 165,996
Gross Unrealized Gains 81 80
Gross Unrealized Losses (212)  
Estimated Fair Value 119,438 166,076
Short-term Investments [Member] | U.S. and Foreign Commercial Paper [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 52,278 51,102
Estimated Fair Value 52,278 51,102
Short-term Investments [Member] | U.S. and Foreign Corporate Debt Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 31,135 56,691
Gross Unrealized Gains   38
Gross Unrealized Losses (128)  
Estimated Fair Value 31,007 56,729
Short-term Investments [Member] | Asset-backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 18,153 39,756
Gross Unrealized Gains   33
Gross Unrealized Losses (84)  
Estimated Fair Value 18,069 39,789
Short-term Investments [Member] | U.S. Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 18,003 18,447
Gross Unrealized Gains 81 9
Estimated Fair Value 18,084 18,456
Maketable Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 172,715 184,593
Gross Unrealized Gains 81 80
Gross Unrealized Losses (212)  
Estimated Fair Value $ 172,585 $ 184,673