CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 89,395	$ 93,108
Marketable securities	276,967	137,548
Restricted cash	33,312	34,964
Accounts receivable	363	2,320
Prepaid expenses and other current assets	19,944	19,317
Total current assets	419,981	287,257
Restricted cash	1,704	2,422
Property and equipment, net	39,668	32,342
Intangible assets, net	10,300	10,793
Goodwill	52,941	53,065
Other non-current assets	410	159
Total assets	525,004	386,038
Current liabilities:
Accounts payable	15,991	11,889
Accrued expenses	26,522	26,734
Accrued interest	5,146	0
Deferred revenue	32,807	34,469
Notes payable	149	395
Deferred rent	1,190	1,409
Other current liabilities	73	1,598
Total current liabilities	81,878	76,494
Deferred revenue	2,500	4,171
Convertible notes payable	315,627	0
Deferred rent	11,552	9,534
Other non-current liabilities	3,330	3,170
Total liabilities	414,887	93,369
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value, 2,000,000 shares authorized; no shares issued and outstanding as of June 30, 2016 and December 31, 2015, respectively	0	0
Common stock, $0.01 par value, 600,000,000 shares authorized at June 30, 2016 and December 31, 2015; 271,334,926 shares issued and 270,879,496 shares outstanding at June 30, 2016 and 270,426,662 shares issued and 269,971,232 shares outstanding at December 31, 2015	2,714	2,704
Additional paid-in capital	925,629	951,569
Accumulated deficit	(806,633)	(650,030)
Treasury stock, 455,430 shares, cost basis at both June 30, 2016 and December 31, 2015	(2,450)	(2,450)
Accumulated other comprehensive loss	(9,143)	(9,124)
Total stockholders’ equity	110,117	292,669
Total liabilities and stockholders’ equity	$ 525,004	$ 386,038