Marketable Securities - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Marketable securities, realized gain	$ 11	$ 276
Marketable securities, realized loss	$ 68	$ 872

Amount of realized gain 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/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563

Name:	us-gaap_DebtSecuritiesAvailableForSaleRealizedGain
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration