Inventories

3 Months Ended

Mar. 31, 2020

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories consisted of the following:

	Millions of Dollars
	March 31 2020		December 31 2019
Crude oil and petroleum products	$	5,008	3,452
Materials and supplies	323		324
	$	5,331	3,776

Inventories valued on the last-in, first-out (LIFO) basis totaled $4,879 million and $3,331 million at March 31, 2020, and December 31, 2019, respectively. We performed a lower-of-cost-or-market evaluation for our crude oil and petroleum products inventory at March 31, 2020, and determined that a write-down was not required based on forward prices. Should crude oil and petroleum product forward prices have a sustained decline, a future lower-of-cost-or-market write‑down may be required.