Revenue - Revenue by product and customer (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Product sales, net	$ 30,499	$ 22,484	$ 78,460	$ 59,522
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Disaggregation of Revenue [Line Items]
Product sales, net				(273)
Implants | Contracted rate | Third party distributor
Disaggregation of Revenue [Line Items]
Product sales, net	11,779	11,102	34,555	26,257
Implants | Contracted rate | Provider or Facility
Disaggregation of Revenue [Line Items]
Product sales, net	3,039	2,632	9,715	8,715
Implants | Time-and-materials Contract | Third party distributor
Disaggregation of Revenue [Line Items]
Product sales, net	4,030	1,612	10,584	5,468
Implants | Time-and-materials Contract | Time-and-materials Contract
Disaggregation of Revenue [Line Items]
Product sales, net	573	490	1,176	1,070
Biopsy kits | Direct bill
Disaggregation of Revenue [Line Items]
Product sales, net	533	488	1,632	1,392
Epicel | Direct bill
Disaggregation of Revenue [Line Items]
Product sales, net	$ 9,889	$ 6,035	$ 20,445	$ 16,893