Cash, cash equivalents and investments - Narrative (Details) - USD ($) |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
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| Cash and Cash Equivalents [Abstract] | |||||
| Cash equivalents | $ 34,900,000 | $ 34,900,000 | $ 64,000,000 | ||
| Realized gains (losses) recognized on available-for-sale investments | $ 0 | $ (200,000) | $ 0 | $ 0 | |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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