Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Product sales, net	$ 22,484	$ 14,260	$ 59,522	$ 40,574
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Disaggregation of Revenue [Line Items]
Product sales, net	125	372	(273)	230
Implants | Contracted rate | Third party distributor
Disaggregation of Revenue [Line Items]
Product sales, net	243	8,046	18,354	11,145
Implants | Third party reimbursement | Third party distributor
Disaggregation of Revenue [Line Items]
Product sales, net	15,593	1,079	23,156	15,172
Biopsy kits | Direct bill
Disaggregation of Revenue [Line Items]
Product sales, net	488	412	1,392	1,274
Epicel | Direct bill
Disaggregation of Revenue [Line Items]
Product sales, net	6,035	$ 4,351	16,893	$ 12,753
License Grants, Milestone and Royalty Payments | Innovative Cellular Therapeutics
Disaggregation of Revenue [Line Items]
Product sales, net					$ 1,200
Agreement with Orsini, Potential Payment if Minimum Payment Obligations Not Achieved
Disaggregation of Revenue [Line Items]
Incremental service fee	$ 1,300		$ 1,300