HollyFrontier Corporation is an independent petroleum refiner that produces refined products, such as gasoline, diesel fuel, jet fuel, specialty lubricant products, and specialty and modified asphalt. The Company operates in two segments: Refining and HEP. The Refining segment includes the operations of the Company�s El Dorado, Tulsa, Navajo, Cheyenne and Woods Cross Refineries, and NK Asphalt, which operates various asphalt terminals in Arizona and New Mexico. The HEP segment involves all of the operations of Holly Energy Partners, L.P. (HEP), a variable interest entity in which the Company owned a 39% interest as of December 31, 2013. The Company owns and operates five refineries having a combined crude oil processing capacity of 443,000 barrels per day that serve markets throughout the Mid-Continent, Southwest and Rocky Mountain regions of the United States.