Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 46,025	$ 54,539
Investments	125,274	138,704
Prepaid expenses and other current assets	5,346	5,126
Total current assets	176,645	198,369
Property and equipment, net	33,724	36,125
Long-term investments		36,752
Restricted cash	1,513	1,400
Total assets	211,882	272,646
Current liabilities:
Accounts payable	5,380	7,587
Accrued expenses and other current liabilities	9,594	10,812
Deferred revenue - related party	12,058	12,058
Total current liabilities	27,032	30,457
Lease incentive obligation, net of current portion	9,424	10,730
Deferred rent	2,202	2,072
Deferred revenue, net of current portion - related party	87,712	96,756
Total liabilities	126,370	140,015
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at September 30, 2017 and December 31, 2016; no shares issued and outstanding at September 30, 2017 and December 31, 2016
Common stock, $0.001 par value; 200,000,000 shares authorized at September 30, 2017 and December 31, 2016; 40,512,639 and 40,355,753 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively	40	40
Additional paid-in capital	320,189	306,931
Accumulated other comprehensive loss	(99)	(149)
Accumulated deficit	(234,618)	(174,191)
Total stockholders’ equity	85,512	132,631
Total liabilities and stockholders’ equity	$ 211,882	$ 272,646