XML 41 R31.htm IDEA: XBRL DOCUMENT v3.20.1
Cash Equivalents and Marketable Securities - Additional Information (Details) - US Government Agencies Debt Securities
$ in Thousands
3 Months Ended
Mar. 31, 2020
USD ($)
Security
Dec. 31, 2019
USD ($)
Security
Mar. 31, 2020
USD ($)
Security
Mar. 31, 2019
USD ($)
Cash Equivalents And Marketable Securities [Line Items]        
Number of debt securities held | Security 25 13 25  
Allowance for Credit Loss $ 0 $ 0 $ 0  
Impairment of marketable securities 0 0    
Realized gains or losses on marketable securities     0 $ 0
Accrued interest receivable on available-for-sale debt securities $ 200 $ 300 $ 200