Condensed Consolidated Statements of Comprehensive Loss (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Net revenues from collaborators	$ 8,275		$ 18,642
Operating expenses:
Research and development	43,758	[1]	22,179	[1]
In-process research and development	224,656
General and administrative	8,925	[1]	6,267	[1]
Total operating expenses	277,339		28,446
Loss from operations	(269,064)		(9,804)
Other income (expense):
Interest income	333		224
Other (expense) income	(82)		5
Total other income	251		229
Loss before income taxes	(268,813)		(9,575)
Benefit from income taxes	17,870		562
Net loss	(250,943)		(9,013)
Net loss per common share - basic and diluted	$ (3.70)		$ (0.15)
Weighted average common shares used to compute basic and diluted net loss per common share	67,786		59,173
Comprehensive loss:
Net loss	(250,943)		(9,013)
Unrealized gain on marketable securities, net of tax	5,313		5,159
Comprehensive loss	$ (245,630)		$ (3,854)

[1] Non-cash stock-based compensation expenses included in operating expenses are as follows: Research and development $ 3,681 $ 2,087 General and administrative 1,910 988