Annual report pursuant to Section 13 and 15(d)

Short-term Investments (Details)

v3.19.1
Short-term Investments (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost $ 32,718 $ 32,424
Unrealized Gains 14 74
Unrealized Losses (15) (79)
Fair Value 32,717 32,419
Commercial paper    
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost 8,772 11,962
Unrealized Gains 0 0
Unrealized Losses 0 0
Fair Value 8,772 11,962
Overnight repurchase agreement    
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost 9,000 9,000
Unrealized Gains 0 0
Unrealized Losses 0 0
Fair Value 9,000 9,000
U.S. government securities    
Schedule of Held-to-maturity Securities [Line Items]    
Amortized Cost 14,946 11,462
Unrealized Gains 14 74
Unrealized Losses (15) (79)
Fair Value $ 14,945 $ 11,457