CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue:
Research and development revenue under collaborative agreements	$ 119,658	$ 56,628	$ 181,551	$ 76,177
Licensing and royalty revenue	770	448	1,461	9,060
Total revenue	120,428	57,076	183,012	85,237
Expenses:
Research, development and patent expenses	68,007	59,264	132,454	112,712
General and administrative	7,775	4,462	15,241	8,842
Total operating expenses	75,782	63,726	147,695	121,554
Income (loss) from operations	44,646	(6,650)	35,317	(36,317)
Other income (expense):
Investment income	917	671	1,761	1,328
Interest expense	(9,127)	(4,961)	(18,148)	(9,904)
Gain (loss) on investments, net	1	(260)	1	137
Income (loss) before income tax (expense) benefit	36,437	(11,200)	18,931	(44,756)
Income tax (expense) benefit	(789)	(881)	0	1,395
Net income (loss)	$ 35,648	$ (12,081)	$ 18,931	$ (43,361)
Basic net income (loss) per share (in dollars per share)	$ 0.30	$ (0.10)	$ 0.16	$ (0.37)
Diluted net income (loss) per share (in dollars per share)	$ 0.29	$ (0.10)	$ 0.15	$ (0.37)
Shares used in computing basic net income (loss) per share (in shares)	119,742	117,588	119,348	117,359
Shares used in computing diluted net income (loss) per share (in shares)	127,779	117,588	124,061	117,359