Credit Facilities (Deerfield Revolver) (Details) - USD ($)				12 Months Ended
	Mar. 31, 2019	Aug. 09, 2018	Jan. 12, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 03, 2017
Line of Credit Facility [Line Items]
Cash paid for debt extinguishment				$ 0	$ 1,310,000	$ 2,515,000
Gain (loss) on extinguishment of debt				(11,756,000)	$ (2,270,000)	$ (6,512,000)
Revolving loan facility
Line of Credit Facility [Line Items]
Debt instrument, stated interest rate	5.50%
Debt issuance costs, noncurrent				600,000.0
Deferred financing cost				400,000.0
Deerfield ELGX Revolver, LLC | Revolving loan facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 50,000,000				$ 50,000,000
Debt issuance costs, gross							$ 1,200,000.0
Cash paid for debt extinguishment			1,310,000.000
Write off of deferred debt issuance cost			1,000,000
Gain (loss) on extinguishment of debt			$ (2,270,000.000)
Debt instrument face amount	$ 120,000,000.0
Commitment fee amount		$ 500,000
Global liquidity requirement	17,500,000.0	22,500,000.0		17,500,000.0
Revolving loan facility				0
Debt issuance costs, net				800,000
Remaining borrowing capacity	$ 24,000,000			$ 18,500,000.0
London Interbank Offered Rate (LIBOR) | Revolving loan facility
Line of Credit Facility [Line Items]
Variable rate, floor	1.00%
Interest accrued	$ 9,750,000
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
Third Anniversary
Line of Credit Facility [Line Items]
Termination fee	0.50%
Thereafter, Fee
Line of Credit Facility [Line Items]
Termination fee	0.00%