Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 33,664	$ 35,688
Available-for-sale securities	33,991	88,340
Restricted cash	101	101
Accounts receivable	1,762	3,313
Prepaid expenses and other current assets	5,366	4,654
Total current assets	74,884	132,096
Restricted cash	584	584
Property and equipment, net	18,273	14,502
Other assets	132	144
Intangible assets, net	1,365	1,525
In-process research and development	6,200	6,200
Goodwill	3,605	3,605
Total assets	105,043	158,656
Current liabilities:
Accounts payable, accrued expenses and other	46,626	37,236
Deferred revenues	59,346	59,275
Deferred rent	1,582	1,285
Long-term debt, current portion	1,058	13,346
Total current liabilities	108,612	111,142
Deferred revenues, net of current portion	9,109	35,682
Deferred rent, net of current portion	5,652	5,401
Deferred tax incentives, net of current portion	417	496
Long-term debt, net of current portion	123,117	106,806
Accrued interest	1,200	1,200
Total liabilities	$ 248,107	$ 260,727
Commitments and contingencies (Note 10)
Non-controlling interest	$ 273	$ 69
Stockholders' deficit:
Preferred stock, $0.01 par value: 10,000 shares authorized at June 30, 2015 and December 31, 2014; no shares issued or outstanding at June 30, 2015 or December 31, 2014
Common stock, $0.01 par value: 200,000 shares authorized at June 30, 2015 and December 31, 2014; 110,798 and 106,697 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	$ 1,108	$ 1,067
Additional paid-in capital	567,754	552,037
Accumulated other comprehensive loss	(6)	(74)
Accumulated deficit	(712,193)	(655,170)
Total stockholders' deficit	(143,337)	(102,140)
Total liabilities, non-controlling interest and stockholders' deficit	$ 105,043	$ 158,656