Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment manager business_activity	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Segment Reporting Information [Line Items]
Number of business activities | business_activity									1
Number of segment managers held accountable for operations | manager									0
Number of reportable segments | segment									1
Revenue	$ 78,225	$ 61,202	$ 64,431	$ 51,558	$ 50,772	$ 45,670	$ 47,061	$ 30,975	$ 255,416	$ 174,478	$ 111,626
Systems Revenue [Member]
Segment Reporting Information [Line Items]
Revenue									130,698	93,015	61,359
Consumable Revenues [Member]
Segment Reporting Information [Line Items]
Revenue									124,718	81,463	50,267
North America [Member]
Segment Reporting Information [Line Items]
Revenue									193,376	134,434	89,150
United States [Member]
Segment Reporting Information [Line Items]
Revenue									180,500	125,000	83,700
International [Member]
Segment Reporting Information [Line Items]
Revenue									$ 62,040	$ 40,044	$ 22,476