Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 77,751	$ 65,086
Available-for-sale securities	14,995	90,116
Restricted cash	101	101
Accounts receivable	6,605	5,857
Prepaid expenses and other current assets	4,396	5,484
Total current assets	103,848	166,644
Restricted cash	584	584
Property and equipment, net	13,731	13,364
Other assets	160	175
Intangible assets, net	1,685	1,845
In-process research and development	6,200	6,200
Goodwill	3,605	3,605
Total assets	129,813	192,417
Current liabilities:
Accounts payable, accrued expenses and other	32,208	38,814
Deferred revenues	46,283	9,336
Deferred rent	1,310	1,336
Long-term debt, current portion	11,052	8,248
Total current liabilities	90,853	57,734
Deferred revenues, net of current portion	3,023	66,139
Deferred rent, net of current portion	5,987	6,538
Deferred tax incentives, net of current portion	740	507
Long-term debt, net of current portion	105,135	103,427
Accrued interest	1,200	1,200
Total liabilities	206,938	235,545
Commitments and contingencies (Note 10)
Non-controlling interest	(13)	337
Stockholders' deficit:
Preferred stock, $0.01 par value: 10,000 shares authorized at June 30, 2014 and December 31, 2013; no shares issued or outstanding at June 30, 2014 or December 31, 2013
Common stock, $0.01 par value: 200,000 shares authorized at June 30, 2014 and December 31, 2013; 104,513 and 102,523 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively	1,045	1,025
Additional paid-in capital	539,785	527,779
Accumulated other comprehensive loss	(3)	(24)
Accumulated deficit	(617,939)	(572,245)
Total stockholders' deficit	(77,112)	(43,465)
Total liabilities, non-controlling interest and stockholders' deficit	$ 129,813	$ 192,417