Commitments and Contingencies	3 Months Ended
Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which we have not recorded an accrued liability, we are unable to estimate a range of possible losses for the reasons discussed in more detail below. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material. Environmental matters—We are subject to federal, state and local laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for noncompliance. At March 31, 2015 and December 31, 2014, accrued liabilities for remediation totaled $2.1 million and $0.6 million, respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or penalties, if any, which may be imposed. Receivables from MPC for indemnification of environmental costs related to incidents occurring prior to our initial public offering completed on October 31, 2012 were $0.2 million at March 31, 2015. There were no receivables from MPC for indemnification at December 31, 2014. Legal Proceedings—In 2003, the State of Illinois brought an action against the Premcor Refining Group, Inc. (“Premcor”) and Apex Refining Company (“Apex”) asserting claims for environmental cleanup related to the refinery owned by these entities in the Hartford/Wood River, Illinois area. In 2006, Premcor and Apex filed third-party complaints against numerous owners and operators of petroleum products facilities in the Hartford/Wood River, Illinois area, including MPL. These complaints, which have been amended since filing, assert claims of common law nuisance and contribution under the Illinois Contribution Act and other laws for environmental cleanup costs that may be imposed on Premcor and Apex by the State of Illinois. There are several third-party defendants in the litigation and MPL has asserted cross-claims in contribution against the various third-party defendants. This litigation is currently pending in the Third Judicial Circuit Court, Madison County, Illinois. While the ultimate outcome of these litigated matters remains uncertain, neither the likelihood of an unfavorable outcome nor the ultimate liability, if any, with respect to this matter can be determined at this time and we are unable to estimate a reasonably possible loss (or range of loss) for this litigation. Under our omnibus agreement, MPC will indemnify us for the full cost of any losses should MPL be deemed responsible for any damages in this lawsuit. Guarantees—We have entered into guarantees with maximum potential undiscounted payments totaling $1.9 million as of March 31, 2015, which consist of leases of vehicles that contain general lease indemnities and guaranteed residual values. Over the years, we have sold various assets in the normal course of our business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require us to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. We are typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because we have little or no past experience with the underlying triggering event upon which a reasonable prediction of the outcome can be based. Contractual commitments—At March 31, 2015, our contractual commitments to acquire property, plant and equipment totaled $61.5 million. Our contractual commitments at March 31, 2015 were primarily related to various projects including a butane cavern in Robinson, Illinois and tank expansion in Patoka, Illinois connecting to MPC’s Southern Access Extension.

Commitments and Contingencies

We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which we have not recorded an accrued liability, we are unable to estimate a range of possible losses for the reasons discussed in more detail below. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material.

Environmental matters—We are subject to federal, state and local laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for noncompliance.

At March 31, 2015 and December 31, 2014, accrued liabilities for remediation totaled $2.1 million and $0.6 million, respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or penalties, if any, which may be imposed. Receivables from MPC for indemnification of environmental costs related to incidents occurring prior to our initial public offering completed on October 31, 2012 were $0.2 million at March 31, 2015. There were no receivables from MPC for indemnification at December 31, 2014.

Legal Proceedings—In 2003, the State of Illinois brought an action against the Premcor Refining Group, Inc. (“Premcor”) and Apex Refining Company (“Apex”) asserting claims for environmental cleanup related to the refinery owned by these entities in the Hartford/Wood River, Illinois area. In 2006, Premcor and Apex filed third-party complaints against numerous owners and operators of petroleum products facilities in the Hartford/Wood River, Illinois area, including MPL. These complaints, which have been amended since filing, assert claims of common law nuisance and contribution under the Illinois Contribution Act and other laws for environmental cleanup costs that may be imposed on Premcor and Apex by the State of Illinois. There are several third-party defendants in the litigation and MPL has asserted cross-claims in contribution against the various third-party defendants. This litigation is currently pending in the Third Judicial Circuit Court, Madison County, Illinois. While the ultimate outcome of these litigated matters remains uncertain, neither the likelihood of an unfavorable outcome nor the ultimate liability, if any, with respect to this matter can be determined at this time and we are unable to estimate a reasonably possible loss (or range of loss) for this litigation. Under our omnibus agreement, MPC will indemnify us for the full cost of any losses should MPL be deemed responsible for any damages in this lawsuit.

Guarantees—We have entered into guarantees with maximum potential undiscounted payments totaling $1.9 million as of March 31, 2015, which consist of leases of vehicles that contain general lease indemnities and guaranteed residual values.

Over the years, we have sold various assets in the normal course of our business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require us to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. We are typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because we have little or no past experience with the underlying triggering event upon which a reasonable prediction of the outcome can be based.

Contractual commitments—At March 31, 2015, our contractual commitments to acquire property, plant and equipment totaled $61.5 million. Our contractual commitments at March 31, 2015 were primarily related to various projects including a butane cavern in Robinson, Illinois and tank expansion in Patoka, Illinois connecting to MPC’s Southern Access Extension.