Significant Accounting Policies, Cash, Cash Equivalents and Investments (Details) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($) Company	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2020 Investment	Sep. 30, 2020 USD ($) Company	Sep. 30, 2019 USD ($)
Cash, Cash Equivalents and Investments [Abstract]
Number of publicly held companies in which there is an equity ownership interest of less than 20% | Company	2				2
Number of privately held companies in which there is an equity ownership interest of less than 20% | Company	5				5
Number of investments in privately held companies that were revalued | Investment				2
Gain on investment	$ 835		$ 0		$ 10,722	$ 0
Dynacure SAS [Member]
Cash, Cash Equivalents and Investments [Abstract]
Gain on investment		$ 6,300
Ribo [Member]
Cash, Cash Equivalents and Investments [Abstract]
Gain on investment		$ 3,000