v3.5.0.2
Related-Party Transactions Related-Party Transactions, Summary of Transactions Narrative (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended
May 13, 2016
Apr. 20, 2016
Sep. 30, 2016
[1]
Mar. 31, 2016
Dec. 31, 2015
Jun. 30, 2015
Mar. 31, 2015
Related Party Transactions              
Concentration risk, percentage       56.00%     56.00%
Imbalance settlement gains       $ 1     $ 2
Reimbursements from Tesoro       $ 6     $ 6
Declaration date       Oct. 18, 2016      
Cash distributions per unit (dollars per unit)         $ 0.78 $ 0.8420  
Distribution declared (including IDRs)       $ 50      
Omnibus Agreement              
Related Party Transactions              
Payment for Administrative Fees       9      
Secondment and Logistics Services Agreement              
Related Party Transactions              
Long-term Purchase Commitment, Amount       $ 2      
Subsequent Event              
Related Party Transactions              
Declaration date   Apr. 20, 2016          
Cash distributions per unit (dollars per unit)   $ 0.81 $ 0.8750        
Distribution declared (including IDRs) $ 59            
[1] This distribution was declared on October 18, 2016 and will be paid on the date of distribution.