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Balance Sheet Details - Short-Term Investments (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Short-term investments |  |
Amortized cost | $ 111,161 | $ 110,933
Unrealized gains | 409 | 45
Unrealized losses | (17) | (311)
Estimated fair value | 111,553 | 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 |  | $ 1,994
Unrealized losses |  | (12)
Estimated fair value |  | $ 1,982
U.S. Government agency bonds | Maximum |  |
Short-term investments |  |
Maturity |  | 1 year
Bank certificates of deposit |  |
Short-term investments |  |
Amortized cost | 12,999 | $ 15,201
Unrealized gains | 7 | 2
Unrealized losses |  | (3)
Estimated fair value | $ 13,006 | $ 15,200
Bank certificates of deposit | Maximum |  |
Short-term investments |  |
Maturity | 1 year | 2 years
Commercial paper |  |
Short-term investments |  |
Amortized cost | $ 7,475 | $ 9,597
Unrealized gains | 8 | 1
Unrealized losses |  | (5)
Estimated fair value | $ 7,483 | $ 9,593
Commercial paper | Maximum |  |
Short-term investments |  |
Maturity | 1 year | 1 year
Corporate notes |  |
Short-term investments |  |
Amortized cost | $ 65,354 | $ 60,923
Unrealized gains | 295 | 24
Unrealized losses | (10) | (194)
Estimated fair value | $ 65,639 | $ 60,753
Corporate notes | Maximum |  |
Short-term investments |  |
Maturity | 3 years | 3 years
Asset-backed securities |  |
Short-term investments |  |
Amortized cost | $ 25,333 | $ 21,918
Unrealized gains | 99 | 18
Unrealized losses | (7) | (94)
Estimated fair value | $ 25,425 | $ 21,842
Asset-backed securities | Maximum |  |
Short-term investments |  |
Maturity | 3 years | 3 years

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