Significant Accounting Policies (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 01, 2019	Mar. 31, 2019	Mar. 31, 2018
Finite-Lived Intangible Assets [Line Items]
GPO administrative fees as percent of purchase volume		3.00%
Capitalized patent costs		$ (174)	$ (38)
Right of use asset		4,075
Lease liability		$ 4,892
Accounting Standards Update 2016-02
Finite-Lived Intangible Assets [Line Items]
Right of use asset	$ 4,300
Rent credit	900
Lease liability	5,200
Effect on opening retained earnings	$ 0