Derivatives For further information regarding the fair value measurement of derivative instruments, including any effect of master netting agreements or collateral, see Note 15. We do not designate any of our commodity derivative instruments as hedges for accounting purposes. Derivatives that are not designated as accounting hedges may include commodity derivatives used to hedge price risk on (1) inventories, (2) fixed price sales of refined products, (3) the acquisition of foreign-sourced crude oil, (4) the acquisition of ethanol for blending with refined products, (5) the sale of NGLs and (6) the purchase of natural gas. The following table presents the gross fair values of derivative instruments, excluding cash collateral, and where they appear on the consolidated balance sheets as of March 31, 2018 and December 31, 2017: | | | | | | | | | (In millions) | March 31, 2018 | Balance Sheet Location | Asset | | Liability | Commodity derivatives | | | | Other current assets | $ | 21 |
| | $ | 60 |
| Other current liabilities(a) | — |
| | 12 |
| Deferred credits and other liabilities(a) | — |
| | 48 |
|
| | | | | | | | | (In millions) | December 31, 2017 | Balance Sheet Location | Asset | | Liability | Commodity derivatives | | | | Other current assets | $ | 127 |
| | $ | 126 |
| Other current liabilities(a) | — |
| | 14 |
| Deferred credits and other liabilities(a) | — |
| | 52 |
|
| | (a) | Includes embedded derivatives. |
The tables below summarize open commodity derivative contracts for crude oil and refined products as of March 31, 2018. | | | | | | | Position | | Total Barrels (In thousands) | Crude Oil(a) | | | | Exchange-traded | Long | | 16,664 |
| Exchange-traded | Short | | (22,145 | ) |
| | (a ) | 94.7 percent of the exchange-traded contracts expire in the second quarter of 2018. |
| | | | | | | Position | | Total Gallons (In thousands) | Refined Products(a) | | | | Exchange-traded | Long | | 159,390 |
| Exchange-traded | Short | | (147,252 | ) |
| | (a ) | 100 percent of the exchange-traded contracts expire in the second quarter of 2018. |
The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income: | | | | | | | | | | Gain (Loss) | (In millions) | Three Months Ended March 31, | Income Statement Location | 2018 | | 2017 | Sales and other operating revenues | $ | (1 | ) | | $ | 16 |
| Cost of revenues | (27 | ) | | (24 | ) | Total | $ | (28 | ) | | $ | (8 | ) |
|