Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 41,899	$ 54,539
Investments	145,174	138,704
Prepaid expenses and other current assets	5,188	5,126
Total current assets	192,261	198,369
Property and equipment, net	36,089	36,125
Long-term investments	15,099	36,752
Restricted cash	1,401	1,400
Total assets	244,850	272,646
Current liabilities:
Accounts payable	5,636	7,587
Accrued expenses and other current liabilities	9,550	10,812
Deferred revenue - related party	12,058	12,058
Total current liabilities	27,244	30,457
Lease incentive obligation, net of current portion	10,295	10,730
Deferred rent	2,117	2,072
Deferred revenue, net of current portion - related party	93,741	96,756
Total liabilities	133,397	140,015
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at March 31, 2017 and December 31, 2016; no shares issued and outstanding at March 31, 2017 and December 31, 2016
Common stock, $0.001 par value; 200,000,000 shares authorized at March 31, 2017 and December 31, 2016; 40,386,878 and 40,355,753 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	40	40
Additional paid-in capital	311,229	306,931
Accumulated other comprehensive income	(151)	(149)
Accumulated deficit	(199,665)	(174,191)
Total stockholders’ equity	111,453	132,631
Total liabilities and stockholders’ equity	$ 244,850	$ 272,646