Revenues - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenue Recognition [Abstract]
Fees to GPOs	$ 2,900	$ 2,200
Short-term deferred revenues, net	108,602		$ 90,894
Deferred cost of sales	15,400		13,100
Deferred revenues recognized	43,400
Short-term deferred revenues, gross			104,000
Long-term deferred revenues	$ 6,019		$ 7,083