Revenue from Contracts with Customers - Revenue Recognition Schedule (Details) - Castle Creek Pharmaceuticals, LLC Co-Development And License Agreement - USD ($) $ in Millions	Jun. 30, 2019	Apr. 12, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 9.9	$ 10.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation satisfaction period (in months or years)	6 months
Remaining performance obligation	$ 4.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation satisfaction period (in months or years)	1 year
Remaining performance obligation	$ 4.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation satisfaction period (in months or years)	1 year
Remaining performance obligation	$ 0.9