Inventories	3 Months Ended
Inventories	Mar. 31, 2020
Inventories [Abstract]
Inventories	Note 3—Inventories Inventories consisted of the following: Millions of Dollars March 31 December 31 2020 2019 Crude oil and natural gas $ 192 472 Materials and supplies 534 554 $ 726 1,026 As a result of declining commodity prices in the first quarter of 2020, we recorded a lower of cost or market adjustment of $ 228 million to our crude oil and natural gas inventories. This adjustment is included in the “Purchased commodities” line on our consolidated income statement. Inventories valued on the LIFO basis totaled $ 133 million and $ 286 million at March 31, 2020 and December 31, 2019, respectively.