Fair Value Measurements (Schedule of Financial Instruments, Measured at Fair Value on a Recurring Basis) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Assets
Assets, fair value	$ 17,566
Caelum [Member]
Assets
Assets, fair value	17,566
Level 3 [Member]
Assets
Assets, fair value	17,566
Level 3 [Member] \| Caelum [Member]
Assets
Assets, fair value	$ 17,566

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 http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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