CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Revenue from collaborative arrangements (including amounts from a related party: three months-2013-$1,322; 2012-$1,430; six months-2013-$2,644; 2012-$2,860)	$ 1,327	$ 1,430	$ 2,671	$ 128,529
Operating expenses:
Research and development	31,739	29,549	58,155	62,751
General and administrative	11,374	7,590	19,689	15,447
Total operating expenses	43,113	37,139	77,844	78,198
Income (loss) from operations	(41,786)	(35,709)	(75,173)	50,331
Other income (expense), net	8,192		6,770
Interest income	189	90	375	145
Interest expense	(3,024)	(1,501)	(5,761)	(3,002)
Net income (loss)	$ (36,429)	$ (37,120)	$ (73,789)	$ 47,474
Net income (loss) per share:
Basic net income (loss) per share (in dollars per share)	$ (0.37)	$ (0.42)	$ (0.76)	$ 0.55
Diluted net income (loss) per share (in dollars per share)	$ (0.37)	$ (0.42)	$ (0.76)	$ 0.53
Shares used to compute basic earnings per share (in shares)	97,603	89,169	96,964	86,379
Shares used to compute diluted earnings per share (in shares)	97,603	89,169	96,964	95,044