Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue:
Products	$ 76,555	$ 92,708	$ 217,237	$ 257,415
Rentals	7,574	16,966	28,146	45,954
Services	3,813	7,087	11,963	21,284
Total revenue	87,942	116,761	257,346	324,653
Cost of revenue:
Products	49,520	57,315	145,387	155,048
Rentals	3,387	8,272	13,315	22,444
Services	2,160	3,074	6,283	9,042
Depreciation	1,648	2,022	5,355	6,051
Total cost of revenue	$ 56,715	$ 70,683	$ 170,340	$ 192,585