Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current Assets:
Cash and cash equivalents	$ 52,299	$ 256,965
Short-term investments	183,718	0
Accounts receivable	3,362	3,530
Restricted investments	4,000	7,250
Other current assets	26,436	3,061
Total Current Assets	269,815	270,806
Restricted investments	647	647
Property and equipment, net of accumulated depreciation and amortization of $18,865 and $17,328 as of September 30, 2014 and December 31, 2013, respectively	37,178	15,049
Patent costs, net of accumulated amortization of $1,972 and $1,622 as of September 30, 2014 and December 31, 2013, respectively	5,689	5,042
Other assets	5,729	25
Total Assets	319,058	291,569
Current Liabilities:
Accounts payable	967	8,080
Accrued expenses	14,824	14,601
Current portion of long-term debt	97	92
Current portion of notes payable	2,415	0
Warrant liability	0	9,006
Deferred revenue	3,362	3,299
Other liabilities	1,061	888
Total Current Liabilities	22,726	35,966
Long-term debt	1,501	1,576
Notes payable	2,262	0
Deferred rent	6,365	6,835
Total Liabilities	32,854	44,377
Commitments and contingencies
Stockholders' Equity:
Preferred stock, $.0001 par value, 3,333,333 shares authorized; none issued and outstanding	0	0
Common stock, $.0001 par value, 50,000,000 shares authorized; 41,304,851 and 37,751,920 issued and outstanding as of September 30, 2014 and December 31, 2013, respectively	4	4
Additional paid-in capital	920,864	790,424
Accumulated other comprehensive loss	(55)	0
Accumulated deficit	(634,609)	(543,236)
Total Stockholders' Equity	286,204	247,192
Total Liabilities and Stockholders' Equity	$ 319,058	$ 291,569