v3.7.0.1
FAIR VALUE DISCLOSURE (Details) - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents $ 18,747 $ 25,244
Total cash equivalents and short-term investments, Amortized Cost 64,710 67,683
Total cash equivalents and short-term investments, Gross Unrealized Gain (Loss) (37) (31)
Total cash equivalents and short-term investments, Fair Value 64,673 67,652
Short-term Investments 45,926 42,408
Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents, Amortized Cost 15,751 25,244
Cash equivalents 15,751 25,244
Level 1 | Money market funds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents, Amortized Cost 15,751 25,244
Cash equivalents 15,751 25,244
Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 2,996 0
Short-term investments 48,922 42,408
Securities, Amortized cost 48,959 42,439
Securities, Gross Unrealized Gain (Loss) (37) (31)
Short-term Investments 45,926 42,408
Level 2 | U.S.agency securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents, Amortized Cost 2,996  
Cash equivalents 2,996  
Level 2 | U.S. treasuries    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Short-term investments 22,485 22,497
Securities, Amortized cost 22,512 22,516
Securities, Gross Unrealized Gain (Loss) (27) (19)
Short-term Investments 22,485 22,497
Level 2 | Corporate securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Short-term investments 15,048 7,341
Securities, Amortized cost 15,058 7,353
Securities, Gross Unrealized Gain (Loss) (10) (12)
Short-term Investments 15,048 7,341
Level 2 | Commercial paper    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Short-term investments 8,393 12,570
Securities, Amortized cost 8,393 12,570
Securities, Gross Unrealized Gain (Loss) 0 0
Short-term Investments $ 8,393 $ 12,570