Investments (Investments in Marketable Equity Securities) (Details 1) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Investments [Abstract]
Total Cost	$ 280,883	$ 232,847
Gross unrealized gains	419,469	340,255
Total Fair Value	$ 700,352	$ 573,102

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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