Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue:
Products	$ 67,176	$ 76,555	$ 200,206	$ 217,237
Rentals	4,168	7,574	11,366	28,146
Services	2,335	3,813	6,715	11,963
Total revenue	73,679	87,942	218,287	257,346
Cost of revenue:
Products	44,073	49,520	131,464	145,387
Rentals	1,379	3,387	3,704	13,315
Services	2,018	2,160	5,730	6,283
Depreciation	843	1,648	3,173	5,355
Total cost of revenue	$ 48,313	$ 56,715	$ 144,071	$ 170,340