Commitments and Contingencies Schedules of Unfunded Commitments (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Healthcare Royalty Partners | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 5,867	[1]
Healthcare Royalty Partners | Commitment to Invest
Other Commitments [Line Items]
Commitments term	2 years
Eclipse Ventures Fund I, L.P. | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 98
Eclipse Ventures Fund I, L.P. | Commitment to Invest
Other Commitments [Line Items]
Commitments term	5 years
Lagunita Biosciences, LLC | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 500
Lagunita Biosciences, LLC | Commitment to Invest
Other Commitments [Line Items]
Commitments term	4 years
Eclipse Fund II, L.P. | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 225
Eclipse Fund II, L.P. | Commitment to Invest
Other Commitments [Line Items]
Commitments term	6 years
Eclipse Continuity Fund I, L.P. | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 175
Eclipse Continuity Fund I, L.P. | Commitment to Invest
Other Commitments [Line Items]
Commitments term	7 years
Cowen Healthcare Investments II LP | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 6,891
Cowen Healthcare Investments II LP | Commitment to Invest
Other Commitments [Line Items]
Commitments term	2 years
Cowen Healthcare Investments III LP | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 10,000
Cowen Healthcare Investments III LP | Commitment to Invest
Other Commitments [Line Items]
Commitments term	7 years
Cowen Sustainable Investments I LP | Unfunded Commitments
Other Commitments [Line Items]
Other commitments, unfunded amount	$ 25,000
Cowen Sustainable Investments I LP | Commitment to Invest
Other Commitments [Line Items]
Commitments term	10 years

[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.