v3.7.0.1
Inventories (Details) - USD ($)
$ in Millions
Mar. 31, 2017
Dec. 31, 2016
Inventories    
Crude oil and petroleum products $ 509 $ 418
Materials and supplies 588 600
Total Inventories 1,097 1,018
Inventories (Textual) [Abstract]    
Inventories valued on the LIFO basis 379 269
Excess of current replacement cost over LIFO cost of inventories $ 121 $ 104