Revenue Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Product sales, net									$ 90,857	$ 62,760	$ 54,383
Revenues	$ 31,335	$ 22,484	$ 19,011	$ 18,027	$ 14,260	$ 16,953	$ 9,361	$ 23,350	90,857	63,924	54,383
Sales Channel, Directly to Consumer [Member] | Biopsy Kits [Member]
Disaggregation of Revenue [Line Items]
Product sales, net									1,997	1,764	1,545
Sales Channel, Directly to Consumer [Member] | Epicel
Disaggregation of Revenue [Line Items]
Product sales, net									23,116	18,858	15,512
Revenue, Rights Granted [Member] | Epicel
Disaggregation of Revenue [Line Items]
Product sales, net									0	1,164	0
Fixed-price Contract [Member] | Sales Channel, Through Intermediary [Member] | Implants [Member]
Disaggregation of Revenue [Line Items]
Product sales, net									40,830	30,366	17,027
Time-and-materials Contract [Member] | Sales Channel, Through Intermediary [Member] | Implants [Member]
Disaggregation of Revenue [Line Items]
Product sales, net									25,096	12,122	20,299
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Product sales, net									$ (182)	$ (350)	$ 0