Overview	3 Months Ended
Mar. 31, 2015
Accounting Policies [Abstract]
Overview	Note 1—Overview We are a diversified energy company based in Houston, Texas. Currently, we operate in four segments: (i) refining and distribution, (ii) retail, (iii) natural gas and oil production, and (iv) commodity marketing and logistics. Our refining and distribution segment consists of a refinery in Kapolei, Hawaii, refined products terminals, pipelines, and a single-point mooring. The refinery produces ultra-low sulfur diesel, gasoline, jet fuel, marine fuel, and other associated refined products primarily for consumption in Hawaii. Our retail segment consists of retail outlets which sell gasoline, diesel, and retail merchandise throughout Hawaii. Our retail network includes Tesoro-branded retail sites, company-operated convenience stores, and other sites operated by third parties. Our natural gas and oil production segment consists of natural gas and oil assets that are non-operated and are concentrated in our 33.7% ownership of Piceance Energy, LLC ("Piceance Energy"), a joint venture entity operated by Laramie Energy II, LLC ("Laramie") and focused on producing natural gas in Garfield and Mesa Counties, Colorado. In addition, we own non-operated interests in Colorado and offshore California, and an overriding royalty interest in New Mexico. Our interests are heavily weighted towards natural gas and natural gas liquids. Our commodity marketing and logistics segment focuses on marketing, transporting, and distributing crude oil and refined products. Our logistics capability consists of historical pipeline shipping status, a leased railcar fleet, and expertise in chartering tows and barges, with the capability of moving crude oil from landlocked locations in the Western U.S. and Canada to the refining hubs in the Midwest, Gulf Coast, and East Coast regions of the U.S. and to Hawaii.

Overview

3 Months Ended

Mar. 31, 2015

Note 1—Overview

We are a diversified energy company based in Houston, Texas. Currently, we operate in four segments: (i) refining and distribution, (ii) retail, (iii) natural gas and oil production, and (iv) commodity marketing and logistics.

Our refining and distribution segment consists of a refinery in Kapolei, Hawaii, refined products terminals, pipelines, and a single-point mooring. The refinery produces ultra-low sulfur diesel, gasoline, jet fuel, marine fuel, and other associated refined products primarily for consumption in Hawaii.

Our retail segment consists of retail outlets which sell gasoline, diesel, and retail merchandise throughout Hawaii. Our retail network includes Tesoro-branded retail sites, company-operated convenience stores, and other sites operated by third parties.

Our natural gas and oil production segment consists of natural gas and oil assets that are non-operated and are concentrated in our 33.7% ownership of Piceance Energy, LLC ("Piceance Energy"), a joint venture entity operated by Laramie Energy II, LLC ("Laramie") and focused on producing natural gas in Garfield and Mesa Counties, Colorado. In addition, we own non-operated interests in Colorado and offshore California, and an overriding royalty interest in New Mexico. Our interests are heavily weighted towards natural gas and natural gas liquids.

Our commodity marketing and logistics segment focuses on marketing, transporting, and distributing crude oil and refined products. Our logistics capability consists of historical pipeline shipping status, a leased railcar fleet, and expertise in chartering tows and barges, with the capability of moving crude oil from landlocked locations in the Western U.S. and Canada to the refining hubs in the Midwest, Gulf Coast, and East Coast regions of the U.S. and to Hawaii.