Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 33,642	$ 54,539
Investments	137,570	138,704
Prepaid expenses and other current assets	4,839	5,126
Total current assets	176,051	198,369
Property and equipment, net	34,813	36,125
Long-term investments	3,962	36,752
Restricted cash	1,513	1,400
Total assets	216,339	272,646
Current liabilities:
Accounts payable	3,889	7,587
Accrued expenses and other current liabilities	9,718	10,812
Deferred revenue - related party	12,058	12,058
Total current liabilities	25,665	30,457
Lease incentive obligation, net of current portion	9,859	10,730
Deferred rent	2,159	2,072
Deferred revenue, net of current portion - related party	90,727	96,756
Total liabilities	128,410	140,015
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at June 30, 2017 and December 31, 2016; no shares issued and outstanding at June 30, 2017 and December 31, 2016
Common stock, $0.001 par value; 200,000,000 shares authorized at June 30, 2017 and December 31, 2016; 40,412,035 and 40,355,753 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively	40	40
Additional paid-in capital	315,748	306,931
Accumulated other comprehensive loss	(176)	(149)
Accumulated deficit	(227,683)	(174,191)
Total stockholders’ equity	87,929	132,631
Total liabilities and stockholders’ equity	$ 216,339	$ 272,646