XML 105 R62.htm IDEA: XBRL DOCUMENT v3.19.3
Short-term Investments - Summary of Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Short-term Investments (Details) - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 45,265 $ 119,749
Gross Unrealized Gains 20 0
Gross Unrealized Losses 0 (61)
Aggregate Fair Value 45,285 119,688
U.S. government debt securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 44,925 119,401
Gross Unrealized Gains 20 0
Gross Unrealized Losses 0 (61)
Aggregate Fair Value 44,945 119,340
Certificates of deposit    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 340 348
Gross Unrealized Gains 0 0
Gross Unrealized Losses 0 0
Aggregate Fair Value $ 340 $ 348