Description of Business and Basis of Presentation (Policies)	3 Months Ended
Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	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.
Accounting Policies Related to the Acquisition of QuickChek, Business Combinations	The purchase price of an acquisition is measured as the aggregate of the fair value of the consideration transferred. The purchase price is allocated to the fair values of the tangible and intangible assets acquired and liabilities assumed, with any excess recorded as goodwill. These fair value determinations require judgment and may involve the use of significant estimates and assumptions. The purchase price allocation may be provisional during a measurement period of up to one year to provide reasonable time to obtain the information necessary to identify and measure the assets acquired and liabilities assumed. Any such measurement period adjustments are recognized in the period in which the adjustment amount is determined. Transaction costs associated with the acquisition are expensed as incurred.
Accounting Policies Related to the Acquisition of QuickChek, Goodwill and Intangible Assets	Goodwill represents the excess of the aggregate of the consideration transferred over the net assets acquired and liabilities assumed and is tested annually for impairment, or more frequently if there are indicators of impairment. Acquired finite-lived intangible assets are amortized on a straight-line basis over their estimated useful lives, and are reviewed for impairment when events or circumstances indicate that the asset group to which the intangible assets belong might be impaired. The Company revises the estimated remaining useful life of these assets when events or changes in circumstances warrant a revision. If the Company revises the useful life, the unamortized balance is amortized over the use life on a prospective basis. Indefinite-lived intangibles are tested annually for impairment, or more often if indicators warrant.
Recently Issued Accounting Standards	In March 2020, the FASB issued ASU 2020-04, "Reference Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting". This standard included optional guidance for a limited period of time to help ease the burden in accounting for the effects of reference rate reform. The new standard is effective for all entities through December 31, 2022. The Company does not expect the adoption of this standard to have a material impact on the Company's consolidated financial statements.
Revenue Recognition	Revenue is recognized when obligations under the terms of a contract with our customers are satisfied; generally, this occurs with the transfer of control of our petroleum products, convenience merchandise, Renewable Identification Numbers ("RINs") and other assets to our third-party customers. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring goods or providing services. Excise and sales tax that we collect where we have determined we are the principal in the transaction have been recorded as revenue on a jurisdiction-by-jurisdiction basis. The Company enters into buy/sell and similar arrangements when petroleum products are held at one location but are needed at a different location. The Company often pays or receives funds related to the buy/sell arrangements based on location or quality differences. The Company continues to account for these transactions as non-monetary exchanges under existing accounting guidance and typically reports these on a net basis in the Consolidated Statements of Income. Petroleum product sales (at retail). For our retail store locations, the revenue related to petroleum product sales is recognized as the fuel is pumped to our customers. The transaction price at the pump typically includes some portion of sales or excise taxes as levied in the respective jurisdictions. Those taxes that are collected for remittance to governmental entities on a pass through basis are not recognized as revenue and they are recorded to a liability account until they are paid. Our customers typically use a mixture of cash, checks, credit cards and debit cards to pay for our products as they are received. We have accounts receivable from the various credit/debit card providers at any point in time related to product sales made on credit cards and debit cards. These receivables are typically collected in two to seven days, depending on the terms with the particular credit/debit card providers. Payment fees retained by the credit/debit card providers are recorded as station and other operating expenses. Petroleum product sales (at wholesale). Our sales of petroleum products at wholesale are generally recorded as revenue when the deliveries have occurred and legal ownership of the product has transferred to the customer. Title transfer for bulk refined product sales typically occurs at pipeline custody points and upon trucks loading at product terminals. For bulk pipeline sales, we record receivables from customers that are generally collected within a week from custody transfer date. For our rack product sales, the majority of our customers' accounts are drafted by us within 10 days from product transfer. Merchandise sales. For our retail store locations, the revenue related to merchandise sales is recognized as the customer completes their purchase at our locations. The transaction price typically includes some portion of sales tax as levied in the respective jurisdictions. Those taxes that are collected for remittance to governmental entities on a pass through basis are not recognized as revenue and they are recorded to a liability account until they are paid. As noted above, a mixture of payment types are used for these revenues and the same terms for credit/debit card receivables are realized. The most significant judgment with respect to merchandise sales revenue is determining whether we are the principal or agent for some categories of merchandise such as lottery tickets, lotto tickets, newspapers and other small categories of merchandise. For scratch-off lottery tickets, we have determined we are the principal in the majority of the jurisdictions and therefore we record those sales on a gross basis. We have some categories of merchandise (such as lotto tickets) where we are the agent and the revenues recorded for those transactions are our net commission only. The Company offers a loyalty program through its Murphy USA, Murphy Express, and QuickChek branded retail locations. The customers earn rewards based on their spending or other promotional activities. This program creates a performance obligation which requires us to defer a portion of sales revenue to the loyalty program participants until they redeem their rewards. The rewards may be redeemed for free or discounted merchandise or cash discounts at all stores and on fuel purchases only at Murphy USA and Murphy Express stores. Earned rewards expire after an account is inactive for a period of 90 days at Murphy USA and Murphy Express, while certain QuickChek rewards require use within the month. We recognize loyalty revenue when a customer redeems an earned reward. Deferred revenue associated with both rewards program are included in Trade accounts payable and accrued liabilities in our Consolidated Balance Sheet. The deferred revenue balances at March 31, 2021 and December 31, 2020 were immaterial. RINs sales. For the sale of RINs, we recognize revenue when the RIN is transferred to the counter-party and the sale is completed. Receivables from our counter-parties related to the RIN sales are typically collected within five days of the sale. Other revenues. Items reported as other operating revenues include collection allowances for excise and sales tax and other miscellaneous items and are recognized as revenue when the transaction is completed.
Lease Accounting	The Company determines if an arrangement is a lease or contains a lease at inception. Operating lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Leases with an initial term of 12 months or less are not recorded on the balance sheet; we recognize lease expense for these leases on a straight-line basis over the lease term. The Company's leases have remaining lease terms of approximately 1 year to 35 years, which may include the option to extend the lease when it is reasonably certain the Company will exercise the option. Most leases include one or more options to renew, with renewal terms that can extend the lease term from 5 to 20 years or more. The exercise of lease renewal options is at the Company's sole discretion. Due to the uncertainties of future markets, economic factors, technology changes, demographic shifts and behavior, environmental regulatory requirements and other information that impacts decisions as to station location, management has determined that it was not reasonably certain to exercise contract options and they are not included in the lease term. Additionally, short-term leases and leases with variable lease costs are immaterial. The Company reviews all options to extend, terminate, or otherwise modify its lease agreements to determine if changes are required to the right of use assets and liabilities. As the implicit interest rate is not readily determinable in most of the Company's lease agreements, the Company uses its estimated secured incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. Lessor — We have various arrangements for certain spaces for food service and vending equipment as well as subleases under which we are the lessor. These leases meet the criteria for operating lease classification. Lease income associated with these leases is immaterial. Lessee —We lease land for 392 stations, one terminal, an office building, a hangar and various equipment. Our lease agreements do not contain any material residual value guarantees and approximately 102 sites leased from Walmart contain restrictive covenants, though the restrictions are deemed to have an immaterial impact.

Description of Business and Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2021

Organization, Consolidation and Presentation of Financial Statements [Abstract]

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.

Accounting Policies Related to the Acquisition of QuickChek, Business Combinations

The purchase price of an acquisition is measured as the aggregate of the fair value of the consideration transferred. The purchase price is allocated to the fair values of the tangible and intangible assets acquired and liabilities assumed, with any excess recorded as goodwill. These fair value determinations require judgment and may involve the use of significant estimates and assumptions. The purchase price allocation may be provisional during a measurement period of up to one year to provide reasonable time to obtain the information necessary to identify and measure the assets acquired and liabilities assumed. Any such measurement period adjustments are recognized in the period in which the adjustment amount is determined. Transaction costs associated with the acquisition are expensed as incurred.

Accounting Policies Related to the Acquisition of QuickChek, Goodwill and Intangible Assets

Goodwill represents the excess of the aggregate of the consideration transferred over the net assets acquired and liabilities assumed and is tested annually for impairment, or more frequently if there are indicators of impairment. Acquired finite-lived intangible assets are amortized on a straight-line basis over their estimated useful lives, and are reviewed for impairment when events or circumstances indicate that the asset group to which the intangible assets belong might be impaired. The Company revises the estimated remaining useful life of these assets when events or changes in circumstances warrant a revision. If the Company revises the useful life, the unamortized balance is amortized over the use life on a prospective basis. Indefinite-lived intangibles are tested annually for impairment, or more often if indicators warrant.

Recently Issued Accounting Standards

In March 2020, the FASB issued ASU 2020-04, "Reference Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting". This standard included optional guidance for a limited period of time to help ease the burden in accounting for the effects of reference rate reform. The new standard is effective for all entities through December 31, 2022. The Company does not expect the adoption of this standard to have a material impact on the Company's consolidated financial statements.

Revenue Recognition

Revenue is recognized when obligations under the terms of a contract with our customers are satisfied; generally, this occurs with the transfer of control of our petroleum products, convenience merchandise, Renewable Identification Numbers ("RINs") and other assets to our third-party customers. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring goods or providing services. Excise and sales tax that we collect where we have determined we are the principal in the transaction have been recorded as revenue on a jurisdiction-by-jurisdiction basis.

The Company enters into buy/sell and similar arrangements when petroleum products are held at one location but are needed at a different location. The Company often pays or receives funds related to the buy/sell arrangements based on location or quality differences. The Company continues to account for these transactions as non-monetary exchanges under existing accounting guidance and typically reports these on a net basis in the Consolidated Statements of Income.

Petroleum product sales (at retail). For our retail store locations, the revenue related to petroleum product sales is recognized as the fuel is pumped to our customers. The transaction price at the pump typically includes some portion of sales or excise taxes as levied in the respective jurisdictions. Those taxes that are collected for remittance to governmental entities on a pass through basis are not recognized as revenue and they are recorded to a liability account until they are paid. Our customers typically use a mixture of cash, checks, credit cards and debit cards to pay for our products as they are received. We have accounts receivable from the various credit/debit card providers at any point in time related to product sales made on credit cards and debit cards. These receivables are typically collected in two to seven days, depending on the terms with the particular credit/debit card providers. Payment fees retained by the credit/debit card providers are recorded as station and other operating expenses.

Petroleum product sales (at wholesale). Our sales of petroleum products at wholesale are generally recorded as revenue when the deliveries have occurred and legal ownership of the product has transferred to the customer. Title transfer for bulk refined product sales typically occurs at pipeline custody points and upon trucks loading at product terminals. For bulk pipeline sales, we record receivables from customers that are generally collected within a week from custody transfer date. For our rack product sales, the majority of our customers' accounts are drafted by us within 10 days from product transfer.

Merchandise sales. For our retail store locations, the revenue related to merchandise sales is recognized as the customer completes their purchase at our locations. The transaction price typically includes some portion of sales tax as levied in the respective jurisdictions. Those taxes that are collected for remittance to governmental entities on a pass through basis are not recognized as revenue and they are recorded to a liability account until they are paid. As noted above, a mixture of payment types are used for these revenues and the same terms for credit/debit card receivables are realized.

The most significant judgment with respect to merchandise sales revenue is determining whether we are the principal or agent for some categories of merchandise such as lottery tickets, lotto tickets, newspapers and other small categories of merchandise. For scratch-off lottery tickets, we have determined we are the principal in the majority of the jurisdictions and therefore we record those sales on a gross basis. We have some categories of merchandise (such as lotto tickets) where we are the agent and the revenues recorded for those transactions are our net commission only.

The Company offers a loyalty program through its Murphy USA, Murphy Express, and QuickChek branded retail locations. The customers earn rewards based on their spending or other promotional activities. This program creates a performance obligation which requires us to defer a portion of sales revenue to the loyalty program participants until they redeem their rewards. The rewards may be redeemed for free or discounted merchandise or cash discounts at all stores and on fuel purchases only at Murphy USA and Murphy Express stores. Earned rewards expire after an account is inactive for a period of 90 days at Murphy USA and Murphy Express, while certain QuickChek rewards require use within the month. We recognize loyalty revenue when a customer redeems an earned reward. Deferred revenue associated with both rewards program are included in Trade accounts payable and accrued liabilities in our Consolidated Balance Sheet. The deferred revenue balances at March 31, 2021 and December 31, 2020 were immaterial.

RINs sales. For the sale of RINs, we recognize revenue when the RIN is transferred to the counter-party and the sale is completed. Receivables from our counter-parties related to the RIN sales are typically collected within five days of the sale.

Other revenues. Items reported as other operating revenues include collection allowances for excise and sales tax and other miscellaneous items and are recognized as revenue when the transaction is completed.

Lease Accounting

The Company determines if an arrangement is a lease or contains a lease at inception. Operating lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Leases with an initial term of 12 months or less are not recorded on the balance sheet; we recognize lease expense for these leases on a straight-line basis over the lease term. The Company's leases have remaining lease terms of approximately 1 year to 35 years, which may include the option to extend the lease when it is reasonably certain the Company will exercise the option. Most leases include one or more options to renew, with renewal terms that can extend the lease term from 5 to 20 years or more. The exercise of lease renewal options is at the Company's sole discretion. Due to the uncertainties of future markets, economic factors, technology changes, demographic shifts and behavior, environmental regulatory requirements and other information that impacts decisions as to station location, management has determined that it was not reasonably certain to exercise contract options and they are not included in the lease term. Additionally, short-term leases and leases with variable lease costs are immaterial. The Company reviews all options to extend, terminate, or otherwise modify its lease agreements to determine if changes are required to the right of use assets and liabilities.

As the implicit interest rate is not readily determinable in most of the Company's lease agreements, the Company uses its estimated secured incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments.

Lessor — We have various arrangements for certain spaces for food service and vending equipment as well as subleases under which we are the lessor. These leases meet the criteria for operating lease classification. Lease income associated with these leases is immaterial.

Lessee —We lease land for 392 stations, one terminal, an office building, a hangar and various equipment. Our lease agreements do not contain any material residual value guarantees and approximately 102 sites leased from Walmart contain restrictive covenants, though the restrictions are deemed to have an immaterial impact.