Credit Facilities (Deerfield Warrants Narrative) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Line of Credit Facility [Line Items]
Fair value of warrants issued in connection with the Facility Agreement	$ 0	$ 10,406,000
2017 Deerfield Warrants
Line of Credit Facility [Line Items]
Fair value of warrants issued in connection with the Facility Agreement	2,100,000.0
2018 Deerfield Warrants
Line of Credit Facility [Line Items]
Fair value of warrants issued in connection with the Facility Agreement	$ 2,700,000.0
Facility Agreement, Due 2023 | Facility Agreement, Due 2023, Deerfield Warrants
Line of Credit Facility [Line Items]
Class of warrant or right, expiration date	7 years
Class of warrant or right, exercise limitation threshold	4.985%