Document and Entity Information - shares
6 Months Ended
Jun. 30, 2018
Jul. 19, 2018
Document and Entity Information [Abstract]    
Entity Registrant Name ARQULE INC  
Entity Central Index Key 0001019695  
Trading Symbol arql  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   108,816,985
Document Type 10-Q  
Document Period End Date Jun. 30, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q2