Financial Instruments and Fair Value Measurements - Measurements on Recurring Basis (Details) - Recurring basis - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financial instruments and fair value measurements
Cash equivalents	$ 3,240	$ 44,412
Total	117,527	133,818
Level 1
Financial instruments and fair value measurements
Cash equivalents	3,240	44,412
Total	117,017	133,368
Level 2
Financial instruments and fair value measurements
Total	510	450
Available-for-sale, Debt securities
Financial instruments and fair value measurements
Investments	113,777	88,956
Available-for-sale, Debt securities \| Level 1
Financial instruments and fair value measurements
Investments	113,777	88,956
Equity securities
Financial instruments and fair value measurements
Investments	510	450
Equity securities \| Level 2
Financial instruments and fair value measurements
Investments	510	450
Money market fund
Financial instruments and fair value measurements
Cash equivalents	3,240	40,412
Money market fund \| Level 1
Financial instruments and fair value measurements
Cash equivalents	3,240	40,412
U.S. Treasury Bills
Financial instruments and fair value measurements
Cash equivalents		4,000
U.S. Treasury Bills \| Level 1
Financial instruments and fair value measurements
Cash equivalents		4,000
U.S. Treasury Bills \| Available-for-sale, Debt securities
Financial instruments and fair value measurements
Investments	113,777	88,956
U.S. Treasury Bills \| Available-for-sale, Debt securities \| Level 1
Financial instruments and fair value measurements
Investments	113,777	88,956
Preferred stock \| Equity securities
Financial instruments and fair value measurements
Investments	510	450
Preferred stock \| Equity securities \| Level 2
Financial instruments and fair value measurements
Investments	$ 510	$ 450

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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.

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_PreferredStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: