Condensed Consolidated Balance Sheets (Unaudited) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2014
Dec. 31, 2013
ASSETS    
Cash and cash equivalents $ 28,940 $ 51,612
Short-term investments 29,736 10,384
Accounts receivable 2,107 1,269
Prepaid expenses and other current assets 1,118 1,532
Total current assets 61,901 64,797
Property and equipment, net 6,475 6,079
Long-term investments   15,387
Restricted cash 2,109 2,084
Other assets 30 61
Total 70,515 88,408
Current liabilities:    
Current portion of long-term debt 1,908 1,411
Accounts payable 1,113 2,643
Accrued expenses 3,534 2,408
Current portion of deferred revenue 4,383 5,086
Current portion of deferred rent 403 513
Total current liabilities 11,341 12,061
Long-term liabilities:    
Long-term debt, less current portion 2,401 3,274
Deferred revenue, less current portion 1,538 2,384
Deferred rent, less current portion 1,233 1,375
Total long-term liabilities 5,172 7,033
Total liabilities 16,513 19,094
Commitments and contingencies      
Stockholders' equity:    
Preferred stock, $0.0001 par value-10,000,000 shares authorized, no shares issued and outstanding at June 30, 2014 and December 31, 2013 0 0
Common stock, $0.0001 par value-200,000,000 shares authorized, 16,541,970 shares issued and outstanding at June 30, 2014; 16,438,706 shares issued and 16,410,840 shares outstanding at December 31, 2013 2 2
Additional paid in capital 176,147 174,468
Accumulated deficit (121,509) (104,742)
Accumulated other comprehensive loss (638) (414)
Total stockholders' equity 54,002 69,314
Total $ 70,515 $ 88,408