Credit Facilities (Deerfield Revolver) (Details) - USD ($)				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2019	Aug. 09, 2018	Jun. 30, 2020	Jun. 30, 2019	Jan. 12, 2018
Line of Credit Facility [Line Items]
Commitment fee amount			$ 500,000
Revolving loan facility	$ 0.0			$ 0.0
Credit Agreement
Line of Credit Facility [Line Items]
Debt instrument face amount						$ 50,000,000.0
Global liquidity requirement				17,500,000
Closing
Line of Credit Facility [Line Items]
Commitment fee amount			200,000
First Anniversary
Line of Credit Facility [Line Items]
Commitment fee amount			200,000
Termination fee					2.50%
Second Anniversary
Line of Credit Facility [Line Items]
Commitment fee amount			100,000
Termination fee					1.50%
Expiration
Line of Credit Facility [Line Items]
Commitment fee amount			1,000,000.0
Third Anniversary
Line of Credit Facility [Line Items]
Termination fee					0.50%
Thereafter, Fee
Line of Credit Facility [Line Items]
Termination fee					0.00%
Revolving loan facility
Line of Credit Facility [Line Items]
Debt instrument, stated interest rate					5.50%
Debt issuance costs, noncurrent	600,000			600,000
Deferred financing cost	400,000			400,000
Revolving loan facility | Deerfield ELGX Revolver, LLC
Line of Credit Facility [Line Items]
Debt instrument face amount		$ 120,000,000.0
Global liquidity requirement		$ 17,500,000	$ 22,500,000
Debt issuance costs	$ 600,000			600,000
Revolving loan facility | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Variable rate, floor	1.00%
Interest accrued	$ 9,750,000			$ 9,750,000