Commitments and Contingencies Schedules of Unfunded Commitments (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Healthcare Royalty Partners | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 7,816	[1]
Healthcare Royalty Partners | Commitment to Invest
Other Commitments [Line Items]
Commitments term	4 years 3 months 18 days
Eclipse Ventures Fund I, L.P. | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 59
Eclipse Ventures Fund I, L.P. | Commitment to Invest
Other Commitments [Line Items]
Commitments term	4 years 3 months 18 days
Lagunita Biosciences, LLC | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 250
Lagunita Biosciences, LLC | Commitment to Invest
Other Commitments [Line Items]
Commitments term	3 years 1 month 6 days
Eclipse Fund II, L.P. | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 110
Eclipse Fund II, L.P. | Commitment to Invest
Other Commitments [Line Items]
Commitments term	5 years 3 months 18 days
Eclipse Continuity Fund I, L.P. | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 58
Eclipse Continuity Fund I, L.P. | Commitment to Invest
Other Commitments [Line Items]
Commitments term	6 years 3 months 18 days
Cowen Healthcare Investments II LP | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 1,201
Cowen Healthcare Investments II LP | Commitment to Invest
Other Commitments [Line Items]
Commitments term	1 year 3 months 18 days
Cowen Healthcare Investments III LP | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 6,164
Cowen Healthcare Investments III LP | Commitment to Invest
Other Commitments [Line Items]
Commitments term	6 years 3 months 18 days
Cowen Sustainable Investments I LP | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 3,926
Cowen Sustainable Investments I LP | Commitment to Invest
Other Commitments [Line Items]
Commitments term	9 years 3 months 18 days

[1] The Company is a limited partner of the HealthCare Royalty Partners funds (which are managed by Healthcare Royalty Management) and is a member of HealthCare Royalty Partners General Partners. The Company will make its pro-rata investment in the HealthCare Royalty Partners funds along with the other limited partners.