CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 116,437	$ 24,622
Short-term investments	20,245	21,916
Accounts and other receivables	1,026	806
Prepaid expenses and other current assets	5,821	736
Total current assets	143,529	48,080
Property and equipment, net	2,716	3,150
Deferred income tax assets	371	401
Other assets	4,421	344
Total assets	151,037	51,975
Current liabilities:
Accounts payable	3,359	6,647
Accrued compensation	3,180	4,133
Other current liabilities	4,046	3,896
Deferred revenue	4,769	4,424
Total current liabilities	15,354	19,100
Long-term deferred revenue	32,536	22,303
Other long-term liabilities	1,190	915
Total liabilities	49,080	42,318
Contingencies (Note 12)
Stockholders’ equity:
Common stock and additional paid-in capital — $0.001 par value; 100,000,000 shares authorized; 37,488,535 and 35,950,518 shares issued, respectively; 30,762,150 and 29,263,828 shares outstanding, respectively	240,445	228,046
Accumulated other comprehensive income	109	99
Accumulated deficit	(91,156)	(171,616)
Treasury stock at cost: 6,726,385 shares	(47,441)	(46,872)
Total stockholders’ equity	101,957	9,657
Total liabilities and stockholders’ equity	$ 151,037	$ 51,975