Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 185,606	$ 35,688
Marketable securities		88,340
Restricted cash	101	101
Accounts receivable, net	6,483	3,313
Inventory	3,717
Prepaid expenses and other current assets	5,487	4,623
Total current assets	201,394	132,065
Restricted cash	584	584
Property and equipment, net	21,915	14,502
Other assets	27	25
Intangible assets, net	7,355	7,725
Goodwill	3,605	3,605
Total assets	234,880	158,506
Current liabilities:
Accounts payable, accrued expenses and other	52,082	37,236
Deferred revenues	50,137	59,275
Deferred rent	1,527	1,285
Long-term debt, current portion		13,315
Total current liabilities	103,746	111,111
Deferred revenues, net of current portion	51,197	35,682
Deferred rent, net of current portion	4,926	5,401
Deferred tax incentives, net of current portion	1,045	496
Long-term debt, net of current portion	257,655	106,687
Accrued interest		1,200
Total liabilities	$ 418,569	$ 260,577
Commitments and contingencies
Non-controlling interest	$ 239	$ 69
Stockholders' deficit:
Preferred stock, $0.01 par value: 10,000 shares authorized at December 31, 2015 and 2014; no shares issued or outstanding at December 31, 2015 or 2014
Common stock, $0.01 par value: 200,000 shares authorized at December 31, 2015 and 2014, 115,871 and 106,697 issued and outstanding at December 31, 2015 and 2014, respectively	$ 1,159	$ 1,067
Additional paid-in capital	617,145	552,037
Accumulated other comprehensive loss		(74)
Accumulated deficit	(802,232)	(655,170)
Total stockholders' deficit	(183,928)	(102,140)
Total liabilities, non-controlling interest and stockholders' deficit	$ 234,880	$ 158,506