Significant Accounting Policies, Cash, Cash Equivalents and Investments (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) Company	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) Company	Dec. 31, 2020 USD ($) Investment	Sep. 30, 2020 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	3		3
Number of privately held companies in which there is an equity ownership interest of less than 20% | Company	7		7
Number of investments in privately held companies that were revalued | Investment				3
Gain on investment	$ 4,013	$ 835	$ 4,885		$ 10,722
Dynacure [Member]
Cash, Cash Equivalents and Investments [Abstract]
Gain on investment				$ 6,300
Suzhou-Ribo [Member]
Cash, Cash Equivalents and Investments [Abstract]
Gain on investment				3,000
Aro Biotherapeutics [Member]
Cash, Cash Equivalents and Investments [Abstract]
Gain on investment				$ 5,500