Revenues - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue Recognition [Abstract]
Fees to GPOs	$ 1,700	$ 2,600	$ 4,600	$ 4,800
Short-term deferred revenues, net	107,940		107,940		$ 90,894
Deferred cost of sales	19,600		19,600		13,100
Deferred revenues recognized	20,900		64,300
Short-term deferred revenues, gross					104,000
Long-term deferred revenues	$ 6,101		$ 6,101		$ 7,083