CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 71,167	$ 70,154
Marketable securities	0	21,980
Restricted cash	4,355	10,847
Prepaid expenses and other current assets	13,500	16,295
Total current assets	89,022	119,276
Restricted cash	408	958
Property and equipment, net	12,244	28,426
Intangible assets, net	5,469	6,541
Goodwill	50,305	51,967
Other non-current assets	7,362	810
Total assets	164,810	207,978
Current liabilities:
Accounts payable	4,210	9,301
Accrued expenses	11,553	19,550
Accrued interest	2,031	5,078
Deferred revenue	2,590	10,010
Other current liabilities	1,191	1,600
Total current liabilities	21,575	45,539
Deferred revenue	2,500	2,500
Convertible notes payable	320,255	319,187
Other non-current liabilities	10,318	8,687
Total liabilities	354,648	375,913
Commitments and contingencies
Stockholders' deficit:
Preferred stock, $0.01 par value, 2,000,000 shares authorized; no shares issued and outstanding as of September 30, 2019 and December 31, 2018, respectively	0	0
Common stock, $0.01 par value, 600,000,000 shares authorized at September 30, 2019 and December 31, 2018; 25,575,578 shares issued and 25,528,642 shares outstanding at September 30, 2019 and 19,245,302 shares issued and 19,222,410 shares outstanding at December 31, 2018	256	192
Additional paid-in capital	1,226,314	1,144,621
Accumulated deficit	(1,399,971)	(1,299,107)
Treasury stock, 46,936 shares, cost basis at September 30, 2019 and 22,892 shares, cost basis at December 31, 2018	(2,583)	(2,450)
Accumulated other comprehensive loss	(13,854)	(11,191)
Total stockholders' deficit	(189,838)	(167,935)
Total liabilities and stockholders' deficit	$ 164,810	$ 207,978