Significant Accounting Policies, Cash, Cash Equivalents and Investments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) Company	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Company	Jun. 30, 2019 USD ($)
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
Gain on investment | $	$ 9,625	$ 0	$ 9,887	$ 0
Dynacure SAS [Member]
Cash, Cash Equivalents and Investments [Abstract]
Gain on investment | $	$ 6,300