Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 222,629	$ 164,269
Marketable securities	353,170	353,680
Prepaid expenses and other current assets	7,087	6,016
Total current assets	582,886	523,965
Marketable securities	203,203	347,814
Property and equipment, net	109,299	82,614
Intangible assets, net	22,575	24,456
Goodwill	13,128	13,128
Restricted cash and other non-current assets	10,576	10,360
Total assets	941,667	1,002,337
Current liabilities:
Accounts payable	2,363	6,334
Accrued expenses and other current liabilities	31,810	28,145
Deferred revenue, current portion	6,209	5,889
Total current liabilities	40,382	40,368
Deferred rent, net of current portion	8,714	8,294
Deferred revenue, net of current portion	43,308	35,959
Contingent consideration, net of current portion	3,168	5,082
Construction financing lease obligation	86,626	61,901
Other non-current liabilities	179	237
Total liabilities	182,377	151,841
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.01 par value, 5,000 shares authorized; 0 shares issued and outstanding at June 30, 2016 and December 31, 2015
Common stock, $0.01 par value, 125,000 shares authorized; 37,002 and 36,894 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	370	369
Additional paid-in capital	1,188,847	1,166,585
Accumulated other comprehensive loss	(642)	(2,291)
Accumulated deficit	(429,285)	(314,167)
Total stockholders’ equity	759,290	850,496
Total liabilities and stockholders’ equity	$ 941,667	$ 1,002,337