Quarterly report pursuant to Section 13 or 15(d)

Short-term Investments (Details)

v3.19.2
Short-term Investments (Details) - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost $ 16,080 $ 32,718
Unrealized Gains 10 14
Unrealized Losses (6) (15)
Fair Value 16,084 32,717
Commercial paper    
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost 2,094 8,772
Unrealized Gains 0 0
Unrealized Losses 0 0
Fair Value 2,094 8,772
Overnight repurchase agreement    
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost 3,500 9,000
Unrealized Gains 0 0
Unrealized Losses 0 0
Fair Value 3,500 9,000
U.S. government securities    
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost 10,486 14,946
Unrealized Gains 10 14
Unrealized Losses (6) (15)
Fair Value $ 10,490 $ 14,945