CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue, net	$ 382,329	$ 260,713	$ 189,903
Cost of goods sold	216,049	173,759	129,450
Gross profit	166,280	86,954	60,453
Operating expenses
Research and development	35,365	31,780	20,852
Sales and marketing	8,702	6,627	6,381
General and administrative	35,262	25,527	19,771
Total operating expenses	79,329	63,934	47,004
Income from operations	86,951	23,020	13,449
Other income (expense)
Interest income	221	247	328
Interest expense	(858)	(1,717)	(1,018)
Other income (expense), net	(1,788)	(547)	(1,591)
Total other income (expense)	(2,425)	(2,017)	(2,281)
Income before income taxes	84,526	21,003	11,168
Income tax (expense) benefit	(10,575)	10,231	(375)
Net income	$ 73,951	$ 31,234	$ 10,793
Net income per share basic	$ 3.87	$ 1.82	$ 0.69
Net income per share diluted	$ 3.67	$ 1.76	$ 0.65
Weighted average shares used to compute net income per share: basic	19,097,355	17,201,731	15,626,753
Weighted average shares used to compute net income per share: Diluted	20,139,105	17,712,928	16,532,850