Schedule of Realized Gain (loss) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule of Investments [Abstract]
Sales proceeds	$ 1,400	$ 16,655	$ 16,623	$ 61,164
Realized gains	30	678	1,138	2,450
Realized losses				(2)
Net realized gains	$ 30	$ 678	$ 1,138	$ 2,448

Amount of cash outflow (inflow) through acquisition (sale) of short-term available-for-sale securities.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3098-108585

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585

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