XML 29 R21.htm IDEA: XBRL DOCUMENT
v3.19.3

Short-Term Investments (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2019
Short Term Investments [Abstract] |
Summary of Short-Term Investments | The following is a summary of our short-term investments (in thousands):
|  | September 30, 2019 |
|  |  |  |  |  | Gross |  |  | Gross |  |  |  |  |
|  | Amortized |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
|  | Cost |  |  | Gains |  |  | Losses |  |  | Fair Value |
U.S. treasury bills and government agency obligations |  | $ | 69,702 |  |  | $ | 57 |  |  | $ | — |  |  | $ | 69,759 |
U.S. corporate debt securities |  |  | 29,078 |  |  |  | 23 |  |  |  | — |  |  |  | 29,101 |
Foreign corporate debt securities |  |  | 10,670 |  |  |  | 18 |  |  |  | — |  |  |  | 10,688 |
U.S. commercial paper |  |  | 32,363 |  |  |  | 5 |  |  |  | — |  |  |  | 32,368 |
Foreign commercial paper |  |  | 54,254 |  |  |  | — |  |  |  | — |  |  |  | 54,254 |
Total |  | $ | 196,067 |  |  | $ | 103 |  |  | $ | — |  |  | $ | 196,170 |
|  | December 31, 2018 |
|  |  |  |  |  | Gross |  |  | Gross |  |  |  |  |
|  | Amortized |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
|  | Cost |  |  | Gains |  |  | Losses |  |  | Fair Value |
U.S. treasury bills and government agency obligations |  | $ | 59,747 |  |  | $ | — |  |  | $ | (6 | ) |  | $ | 59,741 |
U.S. corporate debt securities |  |  | 59,164 |  |  |  | — |  |  |  | (77 | ) |  |  | 59,087 |
Foreign corporate debt securities |  |  | 5,041 |  |  |  | 5 |  |  |  | — |  |  |  | 5,046 |
U.S. commercial paper |  |  | 52,800 |  |  |  | — |  |  |  | — |  |  |  | 52,800 |
Foreign commercial paper |  |  | 123,870 |  |  |  | — |  |  |  | (9 | ) |  |  | 123,861 |
Total |  | $ | 300,622 |  |  | $ | 5 |  |  | $ | (92 | ) |  | $ | 300,535 |

X
- Definition Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -URI http://asc.fasb.org/topic&trid=2196928 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_ShortTermInvestmentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration