Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue Recognition
Product revenues	$ 95,619	$ 85,487	$ 188,244	$ 169,467
Operating expenses:
Cost of product revenues	14,383	13,798	33,116	27,471
Research and development	15,312	15,781	32,119	30,655
Selling and marketing	40,337	40,656	82,092	82,163
General and administrative	18,487	18,395	38,205	35,146
Total operating expenses	88,519	88,630	185,532	175,435
Income (loss) from operations	7,100	(3,143)	2,712	(5,968)
Interest income	400	206	817	364
Gain on sale of equity securities				2,807
Unrealized gain on equity securities	1,283		1,410
Other income (expense), net	(248)	357	61	452
Income (loss) before income taxes	8,535	(2,580)	5,000	(2,345)
Income tax expense	218	159	458	1,200
Net income (loss)	$ 8,317	$ (2,739)	$ 4,542	$ (3,545)
Basic net income (loss) per share (in dollars per share)	$ 0.23	$ (0.08)	$ 0.13	$ (0.10)
Diluted net income (loss) per share (in dollars per share)	$ 0.23	$ (0.08)	$ 0.12	$ (0.10)
Shares used in computing basic net income (loss) per share (in shares)	35,544	34,428	35,372	34,219
Shares used in computing diluted net income (loss) per share (in shares)	36,716	34,428	36,360	34,219