CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 95,847	$ 144,353
Marketable securities	115,331	91,126
Restricted cash	27,319	30,314
Prepaid expenses and other current assets	19,952	22,037
Total current assets	258,449	287,830
Restricted cash	1,705	4,590
Property and equipment, net	39,439	40,184
Intangible assets, net	9,161	9,225
Goodwill	51,941	51,673
Other non-current assets	809	799
Total assets	361,504	394,301
Current liabilities:
Accounts payable	3,790	5,685
Accrued expenses	24,650	24,508
Accrued interest	2,031	5,078
Deferred revenue	24,679	30,079
Other current liabilities	1,348	1,056
Total current liabilities	56,498	66,406
Deferred revenue	2,500	2,500
Convertible notes payable	316,695	316,339
Other non-current liabilities	14,910	14,602
Total liabilities	390,603	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 March 31, 2017 and December 31, 2016, respectively	0	0
Common stock, $0.01 par value, 600,000,000 shares authorized at March 31, 2017 and December 31, 2016; 283,069,349 shares issued and 282,613,919 shares outstanding at March 31, 2017 and 271,701,397 shares issued and 271,245,967 shares outstanding at December 31, 2016	2,831	2,717
Additional paid-in capital	956,299	935,997
Accumulated deficit	(974,444)	(929,996)
Treasury stock, 455,430 shares, cost basis at both March 31, 2017 and December 31, 2016	(2,450)	(2,450)
Accumulated other comprehensive loss	(11,335)	(11,814)
Total stockholders’ deficit	(29,099)	(5,546)
Total liabilities and stockholders’ deficit	$ 361,504	$ 394,301