Revenue from Contracts with Customers (Details)		3 Months Ended		6 Months Ended
	Apr. 12, 2019 USD ($) day	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues		$ 21,792,000	$ 0	$ 21,792,000	$ 0
Contract with customer, asset		12,718,000		12,718,000		$ 0
Contract asset - long term		4,279,000		4,279,000
Allowance for credit loss		0		0
Revenue recognized, previously included in contract liability		0		0
Castle Creek Pharmaceuticals, LLC Co-Development And License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract with customer, asset		13,500,000		13,500,000
Remaining performance obligation	$ 10,700,000	9,900,000		9,900,000
Castle Creek Pharmaceuticals, LLC Co-Development And License Agreement | Castle Creek Pharmaceuticals, LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum development costs payable by other party	$ 20,000,000
Excess costs payable by other party (percent)	70.00%
Excess costs payable (percent)	30.00%
Upfront payment received	$ 7,500,000
Value of development services	21,700,000
First milestone payment receivable	2,500,000
Total transaction price at inception	31,700,000
Second milestone payment receivable	30,000,000
Maximum sales milestone payments receivable	75,000,000
First sales milestone payment receivable	25,000,000
First product sales threshold for sales milestone payments	250,000,000
Second sales milestone receivable	50,000,000
Second product sales threshold for sales milestone payments	$ 750,000,000
Gross profit receivable from other party (percent of product sales)	30.00%
Payments due to third party	50.00%
Term of arrangement (years)	40 years
Days written notice required to terminate (days) | day	180
Gross profit owed in event of termination (percentage)	5.00%
Initial transaction price	$ 29,200,000
Maximum payable period (days)	60
Intellectual Property | Castle Creek Pharmaceuticals, LLC Co-Development And License Agreement | Castle Creek Pharmaceuticals, LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Intangible asset	$ 21,000,000
Revenues		21,000,000		21,000,000
License Services | Castle Creek Pharmaceuticals, LLC Co-Development And License Agreement | Castle Creek Pharmaceuticals, LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Fair value (as a percent of overall value)	72.00%
Research and development services
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues		$ 813,000	$ 0	$ 813,000	$ 0
Research and development services | Castle Creek Pharmaceuticals, LLC Co-Development And License Agreement | Castle Creek Pharmaceuticals, LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Fair value (as a percent of overall value)	28.00%
Intangible asset	$ 8,200,000