Selected Quarterly Financial Data - Quarterly Financial Data (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Product sales	$ 8,040	$ 14,672	$ 10,324	$ 11,810	$ 10,405	$ 8,355	$ 9,694	$ 6,945	$ 44,846	$ 35,399	$ 24,864
Total revenue	31,146	60,909	33,862	23,004	21,146	18,412	23,684	17,949	148,921	81,191	71,480
Cost of goods sold	8,960	12,877	5,011	11,661	7,290	7,228	7,203	8,707	38,509	30,428	21,891
Research and development expenses	48,248	43,914	52,230	45,618	46,373	34,016	33,201	35,085	190,010	148,675	126,766
Operating loss	(35,894)	(6,525)	(32,605)	(45,106)	(43,381)	(32,900)	(26,988)	(37,932)	(120,130)	(141,201)	(123,937)
Net loss	$ (47,659)	$ (16,543)	$ (42,748)	$ (55,063)	$ (52,926)	$ (43,547)	$ (34,285)	$ (41,097)	$ (162,013)	$ (171,855)	$ (133,978)
Basic and diluted net loss per share	$ (0.41)	$ (0.14)	$ (0.37)	$ (0.48)	$ (0.46)	$ (0.38)	$ (0.30)	$ (0.36)	$ (1.40)	$ (1.50)	$ (1.19)