Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product Revenue	$ 107,783	$ 102,932	$ 87,696
Licensing, milestone and contract revenue	5,637	447	5,303
Total revenue	113,420	103,379	92,999
Operating expenses:
Cost of product revenue	27,364	24,027	21,053
Research & development	18,787	10,732	8,987
Selling, general & administrative	21,540	18,013	14,825
Total operating expenses	67,691	52,772	44,865
Income from operations	45,729	50,607	48,134
Interest income, net	473	263	120
Income before income taxes	46,202	50,870	48,254
Provision for income taxes	14,386	18,323	17,496
Net income	$ 31,816	$ 32,547	$ 30,758
Basic net income per share:
Net income (in dollars per share)	$ 2.18	$ 2.22	$ 2.06
Basic weighted average common shares outstanding (in shares)	14,575	14,682	14,934
Diluted net income per share:
Net income (in dollars per share)	$ 2.11	$ 2.15	$ 2.01
Diluted weighted average common shares outstanding (in shares)	15,068	15,116	15,321
Net income	$ 31,816	$ 32,547	$ 30,758
Foreign currency translation adjustment	2,533	(668)	(2,154)
Comprehensive income	$ 34,349	$ 31,879	$ 28,604