Fair Value Measurements (Details) - USD ($)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Fair value measurements
Short term investments:	$ 239,575,000	$ 281,783,000
Transfer of assets between levels	0	0
Transfer of liabilities between levels	0	0
Recurring fair value measurement
Fair value measurements
Total assets at fair value	239,575,000	281,743,000
Recurring fair value measurement \| Money market funds
Fair value measurements
Cash equivalents:	188,734,000	281,743,000
Recurring fair value measurement \| Certificates of deposit
Fair value measurements
Cash equivalents:	400,000
Recurring fair value measurement \| U.S. treasury notes
Fair value measurements
Short term investments:	50,441,000
Recurring fair value measurement \| Level 1
Fair value measurements
Total assets at fair value	239,575,000	281,743,000
Recurring fair value measurement \| Level 1 \| Money market funds
Fair value measurements
Cash equivalents:	188,734,000	281,743,000
Recurring fair value measurement \| Level 1 \| Certificates of deposit
Fair value measurements
Cash equivalents:	400,000
Recurring fair value measurement \| Level 1 \| U.S. treasury notes
Fair value measurements
Short term investments:	50,441,000
Recurring fair value measurement \| Level 2
Fair value measurements
Total assets at fair value	0	0
Recurring fair value measurement \| Level 2 \| Money market funds
Fair value measurements
Cash equivalents:	0	0
Recurring fair value measurement \| Level 2 \| Certificates of deposit
Fair value measurements
Cash equivalents:	0
Recurring fair value measurement \| Level 2 \| U.S. treasury notes
Fair value measurements
Short term investments:	0
Recurring fair value measurement \| Level 3
Fair value measurements
Total assets at fair value	0	0
Recurring fair value measurement \| Level 3 \| Money market funds
Fair value measurements
Cash equivalents:	0	$ 0
Recurring fair value measurement \| Level 3 \| Certificates of deposit
Fair value measurements
Cash equivalents:	0
Recurring fair value measurement \| Level 3 \| U.S. treasury notes
Fair value measurements
Short term investments:	$ 0

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- Definition

Represents the transfer of liabilities between the levels of fair value hierarchy that have taken place during the period.

+ References

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
-Paragraph 2
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- Definition

Amount 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/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section S99
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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Fair value portion 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.

+ References

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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.

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No definition available.

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