Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 75,383	$ 74,598
Short-term investments	58,593	126,225
Accounts receivable	10,796
Prepaid expenses and other current assets	4,940	3,169
Total current assets	149,712	203,992
Property and equipment, net	8,032	8,991
Other assets	159	148
Total assets	157,903	213,131
Current liabilities:
Accounts payable	3,933	5,635
Accrued compensation and benefits	3,229	3,161
Accrued and other liabilities	10,709	10,405
Total current liabilities	17,871	19,201
Other long-term liabilities	720	779
Total liabilities	18,591	19,980
Commitments and contingencies (Note 13)
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; no shares issued and outstanding as of December 31, 2017 and 2016
Common stock, $0.0001 par value; 300,000,000 shares authorized; 47,534,979 and 47,309,422 shares issued and outstanding as of December 31, 2017 and December 31, 2016, respectively	5	5
Additional paid-in capital	417,568	407,092
Decrease in accumulated deficit	(278,214)	(213,875)
Accumulated other comprehensive loss	(47)	(71)
Total stockholders' equity	139,312	193,151
Total liabilities and stockholders' equity	$ 157,903	$ 213,131