Inventories (Tables)
 3 Months Ended
Mar. 31, 2018
Inventory Disclosure [Abstract]  
Summary Of Inventories
(In millions)
March 31,
2018
 
December 31,
2017
Crude oil and refinery feedstocks
$
1,777

 
$
2,056

Refined products
2,746

 
2,839

Materials and supplies
435

 
494

Merchandise
153

 
161

Total
$
5,111

 
$
5,550