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Investments (Tables) | 9 Months Ended
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Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract] |
Short-Term and Long-Term Investments Available-for-Sale and Cost Method Investments | The fair value of investments classified as short-term consists of the following:
|  | September 30, 2019 |  |  | December 31, 2018 |
Available-for-sale investments: |  |  |  |  |  |  |  |
Time deposits and certificates of deposit |  | $ | 6,262 |  |  | $ | 102 |
Bankers’ acceptance drafts |  |  | 4,540 |  |  |  | 989 |
Asset-backed securities |  |  | — |  |  |  | 9,113 |
Commercial paper |  |  | 44,981 |  |  |  | 19,359 |
Corporate obligations |  |  | — |  |  |  | 9,352 |
U.S. treasury obligations |  |  | 3,602 |  |  |  | 13,298 |
U.S. agency obligations |  |  | 29,462 |  |  |  | 21,613 |
|  | $ | 88,847 |  |  | $ | 73,826 |
Investments classified as long-term consist of the following:
|  | September 30, 2019 |  |  | December 31, 2018 |
Available-for-sale investments: |  |  |  |  |  |  |  |
Group insurance contracts |  | $ | 5,746 |  |  | $ | 5,890 |
Cost method investments: |  |  |  |  |  |  |  |
Minority interest in a private company |  |  | 4,400 |  |  |  | 4,400 |
|  | $ | 10,146 |  |  | $ | 10,290 |
Gross Unrealized Gains and (Losses) Aggregated by Investment Category | The following tables show the gross unrealized gains and (losses) aggregated by investment category for available-for-sale investments:
As of September 30 , 2019: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Short-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Time deposits and certificates of deposit |  | $ | 6,261 |  |  | $ | 1 |  |  | $ | — |  |  | $ | 6,262 |
Bankers’ acceptance drafts |  |  | 4,540 |  |  |  | — |  |  |  | — |  |  |  | 4,540 |
Commercial paper |  |  | 45,342 |  |  |  | — |  |  |  | (361 | ) |  |  | 44,981 |
U.S. treasury obligations |  |  | 3,601 |  |  |  | 1 |  |  |  | — |  |  |  | 3,602 |
U.S. agency obligations |  |  | 29,460 |  |  |  | 4 |  |  |  | (2 | ) |  |  | 29,462 |
|  | $ | 89,204 |  |  | $ | 6 |  |  | $ | (363 | ) |  | $ | 88,847 |
As of September 30 , 2019: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Long-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Group insurance contracts |  | $ | 5,329 |  |  | $ | 417 |  |  | $ | — |  |  | $ | 5,746 |
As of December 31 , 2018: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Short-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Time deposits and certificates of deposit |  | $ | 102 |  |  | $ | — |  |  | $ | — |  |  | $ | 102 |
Bankers’ acceptance drafts |  |  | 989 |  |  |  | — |  |  |  | — |  |  |  | 989 |
Asset-backed securities |  |  | 9,121 |  |  |  | 1 |  |  |  | (9 | ) |  |  | 9,113 |
Commercial paper |  |  | 19,504 |  |  |  | — |  |  |  | (145 | ) |  |  | 19,359 |
Corporate obligations |  |  | 9,367 |  |  |  | — |  |  |  | (15 | ) |  |  | 9,352 |
U.S. treasury obligations |  |  | 13,294 |  |  |  | 4 |  |  |  | — |  |  |  | 13,298 |
U.S. agency obligations |  |  | 21,617 |  |  |  | 2 |  |  |  | (6 | ) |  |  | 21,613 |
|  | $ | 73,994 |  |  | $ | 7 |  |  | $ | (175 | ) |  | $ | 73,826 |
As of December 31 , 2018: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Long-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Group insurance contracts |  | $ | 5,546 |  |  | $ | 344 |  |  | $ | — |  |  | $ | 5,890 |

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- Definition Investments classified as short-term and long-term available-for-sale investments and long-term cost method investments. + References No definition available. + Details
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- Definition Tabular disclosure of the reconciliation of available-for-sale securities from cost basis to fair value. + References No definition available. + Details
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