Document and Entity Information - shares
9 Months Ended
Sep. 30, 2018
Nov. 02, 2018
Document and Entity Information [Abstract]    
Entity Registrant Name ANDEAVOR LOGISTICS LP  
Entity Central Index Key 0001507615  
Document Type 10-Q  
Document Period End Date Sep. 30, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Current Fiscal Year End Date --12-31  
Entity Emerging Growth Company false  
Entity Small Business false  
Entity Filer Category Large Accelerated Filer  
Limited Partners' Capital Account, Units Issued   245,484,047