CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 112,633	$ 24,622
Short-term investments	17,835	21,916
Accounts and other receivables	1,260	806
Prepaid expenses and other current assets	7,802	736
Total current assets	139,530	48,080
Property and equipment, net	2,540	3,150
Deferred income tax assets	371	401
Other assets	4,254	344
Total assets	146,695	51,975
Current liabilities:
Accounts payable	758	6,647
Accrued compensation	2,573	4,133
Other current liabilities	5,703	3,896
Deferred revenue	4,694	4,424
Total current liabilities	13,728	19,100
Long-term deferred revenue	31,407	22,303
Other long-term liabilities	1,163	915
Total liabilities	46,298	42,318
Contingencies (Note 12)
Stockholders’ equity:
Common stock and additional paid-in capital — $0.001 par value; 100,000,000 shares authorized; 37,526,910 and 35,950,518 shares issued, respectively; 30,800,525 and 29,263,828 shares outstanding, respectively	243,110	228,046
Accumulated other comprehensive income	107	99
Accumulated deficit	(95,379)	(171,616)
Treasury stock at cost: 6,726,385 shares	(47,441)	(46,872)
Total stockholders’ equity	100,397	9,657
Total liabilities and stockholders’ equity	$ 146,695	$ 51,975