CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 75,793	$ 144,353
Marketable securities	111,515	91,126
Restricted cash	30,188	30,314
Prepaid expenses and other current assets	19,187	22,037
Total current assets	236,683	287,830
Restricted cash	17,179	4,590
Property and equipment, net	38,531	40,184
Intangible assets, net	9,475	9,225
Goodwill	52,991	51,673
Other non-current assets	847	799
Total assets	355,706	394,301
Current liabilities:
Accounts payable	8,021	5,685
Accrued expenses	22,305	24,508
Accrued interest	5,078	5,078
Deferred revenue	30,028	30,079
Other current liabilities	1,359	1,056
Total current liabilities	66,791	66,406
Deferred revenue	15,477	2,500
Convertible notes payable	317,051	316,339
Other non-current liabilities	15,449	14,602
Total liabilities	414,768	399,847
Commitments and contingencies
Stockholders’ deficit:
Preferred stock, $0.01 par value, 2,000,000 shares authorized; no shares issued and outstanding as of June 30, 2017 and December 31, 2016, respectively	0	0
Common stock, $0.01 par value, 600,000,000 shares authorized at June 30, 2017 and December 31, 2016; 290,374,408 shares issued and 289,918,978 shares outstanding at June 30, 2017 and 271,701,397 shares issued and 271,245,967 shares outstanding at December 31, 2016	2,904	2,717
Additional paid-in capital	968,996	935,997
Accumulated deficit	(1,018,909)	(929,996)
Treasury stock, 455,430 shares, cost basis at both June 30, 2017 and December 31, 2016	(2,450)	(2,450)
Accumulated other comprehensive loss	(9,603)	(11,814)
Total stockholders’ deficit	(59,062)	(5,546)
Total liabilities and stockholders’ deficit	$ 355,706	$ 394,301