Description of Business and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation — Murphy USA was incorporated in March 2013 and, in connection with its incorporation, Murphy USA issued 100 shares of common stock, par value $0.01 per share, to Murphy Oil Corporation (“Murphy Oil”) for $1.00. On August 30, 2013, Murphy USA was separated from Murphy Oil through the distribution of 100% of the common stock of Murphy USA to holders of Murphy Oil stock. In preparing the financial statements of Murphy USA in conformity with accounting principles generally accepted in the United States, management has made a number of estimates and assumptions related to the reporting of assets, liabilities, revenues, expenses and the disclosure of contingent assets and liabilities. Actual results may differ from these estimates.
Recently Issued Accounting Standards	Recently Issued Accounting Standards— In November 2015, the FASB issued ASU No. 2015-17, "Balance Sheet Classification of Deferred Taxes," which amended existing accounting guidance related to the presentation of deferred tax liabilities and assets. The amended guidance requires that all deferred tax liabilities and assets be classified as noncurrent on the balance sheet. This guidance is effective for reporting periods beginning after December 15, 2016; however, early adoption is permitted at the beginning of a fiscal year. The Company adopted ASU No. 2015-17 during the quarter ended March 31, 2016 and has applied this guidance prospectively to its deferred tax liabilities and assets. For the period ended December 31, 2015, current deferred tax liabilities of $1.7 million remain classified as current in the accompanying balance sheet. In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)" (“ASU 2016-02”). ASU 2016-02 amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets. Lessor accounting will remain similar to lessor accounting under previous GAAP, while aligning with the FASB’s new revenue recognition guidance. ASU 2016-02 is effective for the Company beginning January 1, 2019. Early adoption of ASU 2016-02 is permitted. The standard requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. While this ASU will have impact on our internal processes and controls and result in a change to our accounting, we are still in the evaluation and information gathering stage of implementing the guidance and can not yet estimate the potential impact. On March 30, 2016, the FASB issued ASU No. 2016-09, "Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting", which amends the current stock compensation guidance. The amendments simplify the accounting for the taxes related to stock based compensation, including adjustments to how excess tax benefits and a company’s payments for tax withholdings should be classified. The standard is effective for fiscal periods beginning after December 15, 2016, with early adoption permitted. While we do not anticipate this ASU having a significant financial impact, we are currently evaluating the adoption of this standard on our consolidated financial statements and expect to adopt the standard effective January 1, 2017.