Fair value measurements - Balance sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair value, balance sheet
Cash and cash equivalents	$ 45,095	$ 194,952
Available-For-Sale (Current)	74,200
Estimated Fair Value	151,583
Commercial paper
Fair value, balance sheet
Estimated Fair Value	51,219
Corporate notes / bonds
Fair value, balance sheet
Estimated Fair Value	38,703
Debt security
Fair value, balance sheet
Estimated Fair Value	1,000
Money market funds
Fair value, balance sheet
Estimated Fair Value	2,020
U.S. govt. agencies
Fair value, balance sheet
Estimated Fair Value	33,944
U.S. treasuries
Fair value, balance sheet
Estimated Fair Value	24,697
Recurring
Fair value, balance sheet
Cash and cash equivalents	38,186
Available-For-Sale (Current)	74,200
Available-For-Sale (Non-Current)	39,197
Estimated Fair Value	151,583
Recurring \| Commercial paper
Fair value, balance sheet
Cash and cash equivalents	8,993
Available-For-Sale (Current)	42,226
Estimated Fair Value	51,219
Recurring \| Corporate notes / bonds
Fair value, balance sheet
Available-For-Sale (Current)	17,256
Available-For-Sale (Non-Current)	21,447
Estimated Fair Value	38,703
Recurring \| Debt security
Fair value, balance sheet
Available-For-Sale (Non-Current)	1,000
Estimated Fair Value	1,000
Recurring \| Money market funds
Fair value, balance sheet
Cash and cash equivalents	2,020
Estimated Fair Value	2,020
Recurring \| U.S. govt. agencies
Fair value, balance sheet
Cash and cash equivalents	15,192
Available-For-Sale (Current)	7,881
Available-For-Sale (Non-Current)	10,871
Estimated Fair Value	33,944
Recurring \| U.S. treasuries
Fair value, balance sheet
Cash and cash equivalents	11,981
Available-For-Sale (Current)	6,837
Available-For-Sale (Non-Current)	5,879
Estimated Fair Value	$ 24,697

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
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- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes 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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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