Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue:
Products	$ 65,874	$ 66,160
Rentals	4,052	11,824
Services	2,363	4,389
Total revenue	72,289	82,373
Cost of revenue:
Products	42,474	45,624
Rentals	1,299	6,285
Services	2,096	2,042
Depreciation	1,491	1,895
Total cost of revenue	$ 47,360	$ 55,846