XML 39 R30.htm IDEA: XBRL DOCUMENT v3.19.3
Balance Sheet Details - Short-Term Investments (Details) - USD ($)
$ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2019
Dec. 31, 2018
Short-term investments    
Amortized cost $ 112,916 $ 110,933
Unrealized gains 479 45
Unrealized losses (10) (311)
Estimated fair value 113,385 110,667
U.S. Government bonds    
Short-term investments    
Amortized cost   1,300
Unrealized losses   (3)
Estimated fair value   $ 1,297
U.S. Government bonds | Maximum    
Short-term investments    
Maturity   1 year
U.S. Government agency bonds    
Short-term investments    
Amortized cost 500 $ 1,994
Unrealized losses   (12)
Estimated fair value $ 500 $ 1,982
U.S. Government agency bonds | Maximum    
Short-term investments    
Maturity 1 year 1 year
Bank certificates of deposit    
Short-term investments    
Amortized cost $ 10,500 $ 15,201
Unrealized gains 12 2
Unrealized losses   (3)
Estimated fair value $ 10,512 $ 15,200
Bank certificates of deposit | Maximum    
Short-term investments    
Maturity 1 year 2 years
Commercial paper    
Short-term investments    
Amortized cost $ 9,442 $ 9,597
Unrealized gains 12 1
Unrealized losses   (5)
Estimated fair value $ 9,454 $ 9,593
Commercial paper | Maximum    
Short-term investments    
Maturity 1 year 1 year
Corporate notes    
Short-term investments    
Amortized cost $ 66,697 $ 60,923
Unrealized gains 331 24
Unrealized losses (2) (194)
Estimated fair value $ 67,026 $ 60,753
Corporate notes | Maximum    
Short-term investments    
Maturity 3 years 3 years
Asset-backed securities    
Short-term investments    
Amortized cost $ 25,777 $ 21,918
Unrealized gains 124 18
Unrealized losses (8) (94)
Estimated fair value $ 25,893 $ 21,842
Asset-backed securities | Maximum    
Short-term investments    
Maturity 3 years 3 years