Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 192,588	$ 164,269
Marketable securities	360,515	353,680
Prepaid expenses and other current assets	7,871	6,016
Total current assets	560,974	523,965
Marketable securities	273,762	347,814
Property and equipment, net	96,638	82,614
Intangible assets, net	23,516	24,456
Goodwill	13,128	13,128
Restricted cash and other non-current assets	10,686	10,360
Total assets	978,704	1,002,337
Current liabilities:
Accounts payable	3,136	6,334
Accrued expenses and other current liabilities	29,623	28,145
Deferred revenue, current portion	6,209	5,889
Total current liabilities	38,968	40,368
Deferred rent, net of current portion	8,498	8,294
Deferred revenue, net of current portion	44,861	35,959
Contingent consideration, net of current portion	5,248	5,082
Construction financing lease obligation	74,414	61,901
Other non-current liabilities	208	237
Total liabilities	$ 172,197	$ 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 March 31, 2016 and December 31, 2015
Common stock, $0.01 par value, 125,000 shares authorized; 36,937 and 36,894 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	$ 369	$ 369
Additional paid-in capital	1,177,551	1,166,585
Accumulated other comprehensive loss	(972)	(2,291)
Accumulated deficit	(370,441)	(314,167)
Total stockholders’ equity	806,507	850,496
Total liabilities and stockholders’ equity	$ 978,704	$ 1,002,337