Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Revenue	$ 17,423	$ 19,295
Related-party revenue from Roche	12,955
Total revenue	30,378	19,295
Costs and expenses:
Cost of revenue	10,028	8,916
Cost of Roche related-party revenue	1,362
Selling and marketing	13,793	9,821
General and administrative	9,224	8,842
Research and development	13,456	8,688
Total costs and expenses	47,863	36,267
Loss from operations	(17,485)	(16,972)
Other income:
Interest income	178	7
Total other income	178	7
Net loss	(17,307)	(16,965)
Other comprehensive income:
Unrealized gain on available-for-sale securities	164
Total other comprehensive income	164
Comprehensive loss	$ (17,143)	$ (16,965)
Net loss per common share, basic and diluted	$ (0.50)	$ (0.59)
Weighted-average common shares outstanding, basic and diluted	34,537,007	28,609,345