v3.19.3.a.u2

Financial Instruments (Tables) | 12 Months Ended
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Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract] |
Summary of Cash and Available-for-Sale Securities by Significant Investment Category | The following tables summarize our cash and available-for-sale securities by significant investment category at December 31, 2019 and 2018 (in thousands):
|  | December 31, 2019
|  | Amortized Cost |  | Unrealized Gains |  | Unrealized Losses |  | Fair Value |  | Cash and Cash Equivalents |  | Current Marketable Securities |  | Non- Current Marketable Securities
Cash and cash equivalents |  | $ | 225,874 |  |  | $ | — |  |  | $ | — |  |  | $ | 225,874 |  |  | $ | 225,874 |  |  | $ | — |  |  | $ | — |
Available-for-sale: |  |  |  |  |  |  |  |  |  |  |  |  |  |
Level 2: |  |  |  |  |  |  |  |  |  |  |  |  |  |
Certificates of deposit |  | 82,028 |  |  | 79 |  |  | (6 | ) |  | 82,101 |  |  | 10,002 |  |  | 69,197 |  |  | 2,902 |
U.S. treasury securities |  | 117,891 |  |  | 260 |  |  | (2 | ) |  | 118,149 |  |  | — |  |  | 110,186 |  |  | 7,963 |
Debt securities of U.S. government agencies and corporate entities |  | 834,187 |  |  | 2,708 |  |  | (32 | ) |  | 836,863 |  |  | — |  |  | 687,741 |  |  | 149,122 |
|  | $ | 1,259,980 |  |  | $ | 3,047 |  |  | $ | (40 | ) |  | $ | 1,262,987 |  |  | $ | 235,876 |  |  | $ | 867,124 |  |  | $ | 159,987 |
|  | December 31, 2018
|  | Amortized Cost |  | Unrealized Gains |  | Unrealized Losses |  | Fair Value |  | Cash and Cash Equivalents |  | Current Marketable Securities |  | Non- Current Marketable Securities
Cash and cash equivalents |  | $ | 658,365 |  |  | $ | 20 |  |  | $ | (21 | ) |  | $ | 658,364 |  |  | $ | 658,364 |  |  | $ | — |  |  | $ | — |
Available-for-sale: |  |  |  |  |  |  |  |  |  |  |  |  |  |
Level 2: |  |  |  |  |  |  |  |  |  |  |  |  |  |
Certificates of deposit |  | 173,102 |  |  | 42 |  |  | (36 | ) |  | 173,108 |  |  | — |  |  | 157,920 |  |  | 15,188 |
U.S. treasury securities |  | 152,205 |  |  | 18 |  |  | (48 | ) |  | 152,175 |  |  | — |  |  | 152,175 |  |  | — |
Debt securities of U.S. government agencies and corporate entities |  | 712,065 |  |  | 40 |  |  | (1,335 | ) |  | 710,770 |  |  | — |  |  | 552,968 |  |  | 157,802 |
|  | $ | 1,695,737 |  |  | $ | 120 |  |  | $ | (1,440 | ) |  | $ | 1,694,417 |  |  | $ | 658,364 |  |  | $ | 863,063 |  |  | $ | 172,990 |
Amortized Cost and Estimated Fair Value of Marketable Securities, by Contractual Maturity | The amortized cost and estimated fair value of marketable securities, by contractual maturity at December 31, 2019 and 2018 are as follows (in thousands):
|  | December 31, 2019
|  | Amortized Cost |  | Estimated Fair Value
Due in one year or less |  | $ | 864,958 |  |  | $ | 867,124 |
Due after one year through five years |  | 159,148 |  |  | 159,987 |
Total |  | $ | 1,024,106 |  |  | $ | 1,027,111 |
|  | December 31, 2018
|  | Amortized Cost |  | Estimated Fair Value
Due in one year or less |  | $ | 864,003 |  |  | $ | 863,063 |
Due after one year through five years |  | 173,369 |  |  | 172,990 |
Total |  | $ | 1,037,372 |  |  | $ | 1,036,053 |

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