Basis Of Presentation	9 Months Ended
May 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis Of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“GAAP”) and with the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements of Sonic Corp. (the “Company”). In the opinion of management, these financial statements reflect all adjustments of a normal recurring nature, including recurring accruals, necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the interim periods presented in conformity with GAAP. In certain situations, recurring accruals, including franchise royalties, are based on more limited information at interim reporting dates than at the Company’s fiscal year end due to the abbreviated reporting period. Actual results may differ from these estimates. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto for the fiscal year ended August 31, 2017, included in the Company’s Annual Report on Form 10-K. Interim results are not necessarily indicative of the results that may be expected for a full year or any other interim period. Principles of Consolidation The accompanying financial statements include the accounts of the Company, its wholly owned subsidiaries and a number of Company Drive-Ins in which a subsidiary has a controlling ownership interest. All intercompany accounts and transactions have been eliminated. New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers,” which requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled for the transfer of promised goods or services to customers. The standard also requires additional disclosure regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The ASU will replace most of the existing revenue recognition requirements in U.S. GAAP when it becomes effective. Further, the FASB has issued clarifying guidance with ASU No. 2016-08, “Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net),” ASU No. 2016-10, “Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing,” and ASU No. 2016-20, “Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers.” ASU No. 2016-08 provides guidance for evaluating when another party, along with the entity, is involved in providing a good or service to a customer. ASU No. 2016-10 clarifies assessing whether promises to transfer goods or services are distinct, and whether an entity's promise to grant a license provides a customer with a right to use or right to access the entity's intellectual property. ASU No. 2016-20 provides corrections or improvements to issues that affect narrow aspects of the guidance. The Company plans to adopt the standards in the first quarter of fiscal year 2019 using the cumulative effect transition method. The Company does not believe the new revenue recognition standard will impact the recognition of sales from Company Drive-Ins or the recognition of royalty fees from franchisees, nor will it have a material impact to the recognition of gift card breakage. The Company expects the pronouncement will impact the recognition of the initial franchise fee, which is currently recognized upon the opening of a Franchise Drive-In. The impact on these fees is not expected to be material to total revenue. The Company is finalizing the impact of the required cumulative effect adjustment to be recorded to the balance sheet on the date of initial application and continues to evaluate the effect this pronouncement will have on principal versus agent considerations, other transactions, the financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016-02, “Leases.” The new standard, which replaces existing lease guidance, requires lessees to recognize on the balance sheet a liability to make lease payments and a corresponding right-of-use asset. The guidance also requires certain qualitative and quantitative disclosures designed to assess the amount, timing and uncertainty of cash flows arising from leases. Accounting guidance for lessors is largely unchanged. In January 2018, the FASB issued ASU No. 2018-01. ASU 2018-01 permits an entity to elect an optional transition practical expedient to forgo the evaluation of land easements that existed or expired before the entity’s adoption of 2016-02 and that were not accounted for as leases under previous lease guidance. The standard is effective for fiscal year 2020, with early application permitted. This standard requires adoption based upon a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with optional practical expedients. Based on a preliminary assessment, the Company expects that most of its operating lease commitments will be subject to the new guidance and recognized as operating lease liabilities and right-of-use assets upon adoption, resulting in a significant increase in the assets and liabilities on the consolidated balance sheet. The Company is continuing its assessment, which may identify additional impacts this standard will have on its consolidated financial statements and related disclosures. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments - Credit Losses.” The update was issued to provide more decision-useful information about the expected credit losses on financial instruments. The update replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The update is effective for fiscal year 2021, with early adoption permitted for fiscal years beginning after December 15, 2018. The update should be adopted using a modified-retrospective approach. The Company is currently evaluating the effect this update will have on its financial statements and related disclosures. In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments.” The update is intended to reduce diversity in practice in how certain transactions are classified and will make eight targeted changes to how cash receipts and cash payments are presented in the statement of cash flows. The update is effective for fiscal year 2019. The new standard will require adoption on a retrospective basis unless it is impracticable to apply, in which case the amendments will apply prospectively as of the earliest date practicable. The Company is currently evaluating the effect of this update but does not believe it will have a material impact on its financial statements and related disclosures. In October 2016, the FASB issued ASU No. 2016-16, “Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory,” as part of its simplification initiatives. The update requires that an entity recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs, rather than deferring the recognition until the asset has been sold to an outside party as is required under current GAAP. The update is effective for fiscal year 2019. The new standard will require adoption on a modified retrospective basis through a cumulative-effect adjustment to retained earnings, and early adoption is permitted. The Company is currently evaluating the effect of this update but does not believe it will have a material impact on its financial statements and related disclosures. In November 2016, the FASB issued ASU No. 2016-18, “Statement of Cash Flows - Restricted Cash.” The update requires that restricted cash balances be included in the beginning and ending cash balance within the statement of cash flows. The update is effective for fiscal year 2019. The amendments should be adopted on a retrospective basis for each period presented, and early adoption is permitted. The adoption will increase the beginning and ending cash balance within the Company's statement of cash flows by its restricted cash balances and will require a new disclosure to reconcile the cash balances within the statement of cash flows to the balance sheets. The Company does not expect any other material impacts to its financial statements. In May 2017, the FASB issued ASU No. 2017-09, “Compensation - Stock Compensation: Scope of Modification Accounting,” which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. An entity will account for the effects of a modification unless the fair value of the modified award is the same as the original award, the vesting conditions of the modified award are the same as the original award and the classification of the modified award as an equity instrument or liability instrument is the same as the original award. The update is effective for fiscal year 2019. The update is to be adopted prospectively to an award modified on or after the adoption date. Early adoption is permitted. The Company is currently evaluating the effect of this update but does not believe it will have a material impact on its financial statements and related disclosures. The Company has reviewed all other recently issued accounting pronouncements and concluded they are not applicable or not expected to be significant to our operations.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“GAAP”) and with the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements of Sonic Corp. (the “Company”). In the opinion of management, these financial statements reflect all adjustments of a normal recurring nature, including recurring accruals, necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the interim periods presented in conformity with GAAP. In certain situations, recurring accruals, including franchise royalties, are based on more limited information at interim reporting dates than at the Company’s fiscal year end due to the abbreviated reporting period. Actual results may differ from these estimates. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto for the fiscal year ended August 31, 2017, included in the Company’s Annual Report on Form 10-K. Interim results are not necessarily indicative of the results that may be expected for a full year or any other interim period.

Principles of Consolidation

The accompanying financial statements include the accounts of the Company, its wholly owned subsidiaries and a number of Company Drive-Ins in which a subsidiary has a controlling ownership interest. All intercompany accounts and transactions have been eliminated.

New Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers,” which requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled for the transfer of promised goods or services to customers. The standard also requires additional disclosure regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The ASU will replace most of the existing revenue recognition requirements in U.S. GAAP when it becomes effective. Further, the FASB has issued clarifying guidance with ASU No. 2016-08, “Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net),” ASU No. 2016-10, “Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing,” and ASU No. 2016-20, “Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers.” ASU No. 2016-08 provides guidance for evaluating when another party, along with the entity, is involved in providing a good or service to a customer. ASU No. 2016-10 clarifies assessing whether promises to transfer goods or services are distinct, and whether an entity's promise to grant a license provides a customer with a right to use or right to access the entity's intellectual property. ASU No. 2016-20 provides corrections or improvements to issues that affect narrow aspects of the guidance.

The Company plans to adopt the standards in the first quarter of fiscal year 2019 using the cumulative effect transition method. The Company does not believe the new revenue recognition standard will impact the recognition of sales from Company Drive-Ins or the recognition of royalty fees from franchisees, nor will it have a material impact to the recognition of gift card breakage. The Company expects the pronouncement will impact the recognition of the initial franchise fee, which is currently recognized upon the opening of a Franchise Drive-In. The impact on these fees is not expected to be material to total revenue. The Company is finalizing the impact of the required cumulative effect adjustment to be recorded to the balance sheet on the date of initial application and continues to evaluate the effect this pronouncement will have on principal versus agent considerations, other transactions, the financial statements and related disclosures.

In February 2016, the FASB issued ASU No. 2016-02, “Leases.” The new standard, which replaces existing lease guidance, requires lessees to recognize on the balance sheet a liability to make lease payments and a corresponding right-of-use asset. The guidance also requires certain qualitative and quantitative disclosures designed to assess the amount, timing and uncertainty of cash flows arising from leases. Accounting guidance for lessors is largely unchanged. In January 2018, the FASB issued ASU No. 2018-01. ASU 2018-01 permits an entity to elect an optional transition practical expedient to forgo the evaluation of land easements that existed or expired before the entity’s adoption of 2016-02 and that were not accounted for as leases under previous lease guidance. The standard is effective for fiscal year 2020, with early application permitted. This standard requires adoption based upon a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with optional practical expedients. Based on a preliminary assessment, the Company expects that most of its operating lease commitments will be subject to the new guidance and recognized as operating lease liabilities and right-of-use assets upon adoption, resulting in a significant increase in the assets and liabilities on the consolidated balance sheet. The Company is continuing its assessment, which may identify additional impacts this standard will have on its consolidated financial statements and related disclosures.

In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments - Credit Losses.” The update was issued to provide more decision-useful information about the expected credit losses on financial instruments. The update replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The update is effective for fiscal year 2021, with early adoption permitted for fiscal years beginning after December 15, 2018. The update should be adopted using a modified-retrospective approach. The Company is currently evaluating the effect this update will have on its financial statements and related disclosures.

In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments.” The update is intended to reduce diversity in practice in how certain transactions are classified and will make eight targeted changes to how cash receipts and cash payments are presented in the statement of cash flows. The update is effective for fiscal year 2019. The new standard will require adoption on a retrospective basis unless it is impracticable to apply, in which case the amendments will apply prospectively as of the earliest date practicable. The Company is currently evaluating the effect of this update but does not believe it will have a material impact on its financial statements and related disclosures.

In October 2016, the FASB issued ASU No. 2016-16, “Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory,” as part of its simplification initiatives. The update requires that an entity recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs, rather than deferring the recognition until the asset has been sold to an outside party as is required under current GAAP. The update is effective for fiscal year 2019. The new standard will require adoption on a modified retrospective basis through a cumulative-effect adjustment to retained earnings, and early adoption is permitted. The Company is currently evaluating the effect of this update but does not believe it will have a material impact on its financial statements and related disclosures.

In November 2016, the FASB issued ASU No. 2016-18, “Statement of Cash Flows - Restricted Cash.” The update requires that restricted cash balances be included in the beginning and ending cash balance within the statement of cash flows. The update is effective for fiscal year 2019. The amendments should be adopted on a retrospective basis for each period presented, and early adoption is permitted. The adoption will increase the beginning and ending cash balance within the Company's statement of cash flows by its restricted cash balances and will require a new disclosure to reconcile the cash balances within the statement of cash flows to the balance sheets. The Company does not expect any other material impacts to its financial statements.

In May 2017, the FASB issued ASU No. 2017-09, “Compensation - Stock Compensation: Scope of Modification Accounting,” which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. An entity will account for the effects of a modification unless the fair value of the modified award is the same as the original award, the vesting conditions of the modified award are the same as the original award and the classification of the modified award as an equity instrument or liability instrument is the same as the original award. The update is effective for fiscal year 2019. The update is to be adopted prospectively to an award modified on or after the adoption date. Early adoption is permitted. The Company is currently evaluating the effect of this update but does not believe it will have a material impact on its financial statements and related disclosures.

The Company has reviewed all other recently issued accounting pronouncements and concluded they are not applicable or not expected to be significant to our operations.