Quarterly report pursuant to Section 13 or 15(d)

Available-for-Sale Securities - Summary of Available-For-Sale Securities Recorded in Cash and Cash Equivalents or Marketable Securities (Details)

v3.19.1
Available-for-Sale Securities - Summary of Available-For-Sale Securities Recorded in Cash and Cash Equivalents or Marketable Securities (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Amortized Cost $ 82,619  
Fair Value 82,664  
Fair Value, Measurements, Recurring    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Amortized Cost 100,969 $ 106,427
Unrealized Gains 45 4
Unrealized Losses   (25)
Fair Value 101,014 106,406
Fair Value, Measurements, Recurring | Money Market Funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Amortized Cost 18,349 23,156
Fair Value 18,349 23,156
Fair Value, Measurements, Recurring | U.S. Treasury Securities    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Amortized Cost 13,691 25,698
Unrealized Gains 4  
Unrealized Losses   (6)
Fair Value 13,695 25,692
Fair Value, Measurements, Recurring | Commercial paper    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Amortized Cost 19,342 19,203
Unrealized Gains 15  
Unrealized Losses   (13)
Fair Value 19,357 19,190
Fair Value, Measurements, Recurring | Corporate debt securities    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Amortized Cost 20,521 20,449
Unrealized Gains 17 4
Unrealized Losses   (2)
Fair Value 20,538 20,451
Fair Value, Measurements, Recurring | Government agency bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Amortized Cost 29,066 17,921
Unrealized Gains 9  
Unrealized Losses   (4)
Fair Value $ 29,075 $ 17,917