Credit Facilities (Deerfield Warrants Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
2017 Deerfield Warrants
Line of Credit Facility [Line Items]
Fair Value Adjustment of Warrants	$ 2.1
2018 Deerfield Warrants
Line of Credit Facility [Line Items]
Fair Value Adjustment of Warrants	$ 2.7
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%