Debt	9 Months Ended
May 31, 2016
Debt [Abstract]
Debt	7.Debt On May 17, 2016, various subsidiaries of the Company (the “Co-Issuers”) issued $425.0 million of Series 2016-1 Senior Secured Fixed Rate Notes, Class A-2 (the “2016 Fixed Rate Notes”) in a private transaction which bears interest at 4.47% per annum. The 2016 Fixed Rate Notes have an expected life of seven years with an anticipated repayment date in May 2023. At May 31, 2016, the balance outstanding under the 2016 Fixed Rate Notes including accrued interest totaled $425.7 million and carried a weighted-average interest cost of 4.79%, including the effect of the loan origination costs described below. The Co-Issuers also entered into a securitized financing facility of Series 2016-1 Senior Secured Variable Funding Notes, Class A-1 (the “2016 Variable Funding Notes” and, together with the 2016 Fixed Rate Notes, the “2016 Notes”). This revolving credit facility allows for the issuance of up to $150.0 million of 2016 Variable Funding Notes and certain other credit instruments, including letters of credit. Interest on the 2016 Variable Funding Notes is based on the one-month London Interbank Offered Rate or Commercial Paper, depending on the funding source, plus 2.0%, per annum. An annual commitment fee of 0.5% is payable monthly on the unused portion of the 2016 Variable Funding Notes facility. The 2016 Variable Funding Notes have an expected life of five years with an anticipated repayment date in May 2021 with two one-year options available upon certain conditions including meeting a minimum debt service coverage ratio threshold. At May 31, 2016, there was no balance outstanding under the 2016 Variable Funding Notes. Sonic used a portion of the net proceeds from the issuance of the 2016 Fixed Rate Notes to repay its existing Series 2011-1 Senior Secured Fixed Rate Notes, Class A-2 (the “2011 Fixed Rate Notes”) and Series 2011‑1 Senior Secured Variable Funding Notes, Class A-1 (the “2011 Variable Funding Notes” and, together with the 2011 Fixed Rate Notes, the “2011 Notes”) in full and to pay the costs associated with the securitized financing transaction, including prepayment premiums. Loan origination costs associated with the Company’s 2016 transaction totaled $12.6 million and were allocated among the 2016 Notes. Loan costs are being amortized over each note’s expected life, and the unamortized balance is categorized as “debt origination costs, net” on the Condensed Consolidated Balance Sheets. While the 2016 Fixed Rate Notes and the 2016 Variable Rate Notes are structured to provide for seven-year and five-year lives, respectively, they have a legal final maturity date of May 2046. The Company intends to repay or refinance the 2016 Notes on or before the end of their respective expected lives. In the event the 2016 Notes are not paid in full by the end of their expected lives, the Notes are subject to an upward adjustment in the annual interest rate of at least 5%. In addition, principal payments will accelerate by applying all of the royalties, lease revenues and other fees securing the debt, after deducting certain expenses, until the debt is paid in full. Also, any unfunded amount under the 2016 Variable Funding Notes will become unavailable. The Co-Issuers and Sonic Franchising LLC (the “Guarantor”) are existing special purpose, bankruptcy remote, indirect subsidiaries of Sonic Corp. that hold substantially all of Sonic’s franchising assets and real estate. As of May 31, 2016, assets for these combined indirect subsidiaries totaled $315.4 million, including receivables for royalties, certain Company and Franchise Drive-In real estate, intangible assets and restricted cash balances of $11.0 million. The 2016 Notes are secured by franchise fees, royalty payments and lease payments, and the repayment of the 2016 Notes is expected to be made solely from the income derived from the Co-Issuer’s assets. In addition, the Guarantor, a Sonic Corp. subsidiary that acts as a franchisor, has guaranteed the obligations of the Co-Issuers under the 2016 Notes and pledged substantially all of its assets to secure those obligations. Neither Sonic Corp., the ultimate parent of the Co-Issuers and the Guarantor, nor any other subsidiary of Sonic, guarantees or in any way is liable for the obligations of the Co-Issuers under the 2016 Notes. The Company has, however, agreed to cause the performance of certain obligations of its subsidiaries, principally related to managing the assets included as collateral for the 2016 Notes and certain indemnity obligations relating to the transfer of the collateral assets to the Co-Issuers. The 2016 Notes are subject to a series of covenants and restrictions similar to the Company’s 2011 Notes and customary for transactions of this type. If certain covenants or restrictions are not met, the 2016 Notes are subject to customary accelerated repayment events and events of default. Although management does not anticipate an event of default or any other event of noncompliance with the provisions of the debt, if such event occurred, the unpaid amounts outstanding could become immediately due and payable. In connection with the 2016 transaction described above, the Company recognized an $8.8 million loss from the early extinguishment of debt during the third quarter of fiscal year 2016, which primarily consisted of a $5.9 million prepayment premium and the $2.9 million write-off of unamortized deferred loan fees remaining from the refinanced debt.

7.Debt

On May 17, 2016, various subsidiaries of the Company (the “Co-Issuers”) issued $425.0 million of Series 2016-1 Senior Secured Fixed Rate Notes, Class A-2 (the “2016 Fixed Rate Notes”) in a private transaction which bears interest at 4.47% per annum. The 2016 Fixed Rate Notes have an expected life of seven years with an anticipated repayment date in May 2023. At May 31, 2016, the balance outstanding under the 2016 Fixed Rate Notes including accrued interest totaled $425.7 million and carried a weighted-average interest cost of 4.79%, including the effect of the loan origination costs described below.

The Co-Issuers also entered into a securitized financing facility of Series 2016-1 Senior Secured Variable Funding Notes, Class A-1 (the “2016 Variable Funding Notes” and, together with the 2016 Fixed Rate Notes, the “2016 Notes”). This revolving credit facility allows for the issuance of up to $150.0 million of 2016 Variable Funding Notes and certain other credit instruments, including letters of credit. Interest on the 2016 Variable Funding Notes is based on the one-month London Interbank Offered Rate or Commercial Paper, depending on the funding source, plus 2.0%, per annum. An annual commitment fee of 0.5% is payable monthly on the unused portion of the 2016 Variable Funding Notes facility. The 2016 Variable Funding Notes have an expected life of five years with an anticipated repayment date in May 2021 with two one-year options available upon certain conditions including meeting a minimum debt service coverage ratio threshold. At May 31, 2016, there was no balance outstanding under the 2016 Variable Funding Notes.

Sonic used a portion of the net proceeds from the issuance of the 2016 Fixed Rate Notes to repay its existing Series 2011-1 Senior Secured Fixed Rate Notes, Class A-2 (the “2011 Fixed Rate Notes”) and Series 2011‑1 Senior Secured Variable Funding Notes, Class A-1 (the “2011 Variable Funding Notes” and, together with the 2011 Fixed Rate Notes, the “2011 Notes”) in full and to pay the costs associated with the securitized financing transaction, including prepayment premiums.

Loan origination costs associated with the Company’s 2016 transaction totaled $12.6 million and were allocated among the 2016 Notes. Loan costs are being amortized over each note’s expected life, and the unamortized balance is categorized as “debt origination costs, net” on the Condensed Consolidated Balance Sheets.

While the 2016 Fixed Rate Notes and the 2016 Variable Rate Notes are structured to provide for seven-year and five-year lives, respectively, they have a legal final maturity date of May 2046. The Company intends to repay or refinance the 2016 Notes on or before the end of their respective expected lives. In the event the 2016 Notes are not paid in full by the end of their expected lives, the Notes are subject to an upward adjustment in the annual interest rate of at least 5%. In addition, principal payments will accelerate by applying all of the royalties, lease revenues and other fees securing the debt, after deducting certain expenses, until the debt is paid in full. Also, any unfunded amount under the 2016 Variable Funding Notes will become unavailable.

The Co-Issuers and Sonic Franchising LLC (the “Guarantor”) are existing special purpose, bankruptcy remote, indirect subsidiaries of Sonic Corp. that hold substantially all of Sonic’s franchising assets and real estate. As of May 31, 2016, assets for these combined indirect subsidiaries totaled $315.4 million, including receivables for royalties, certain Company and Franchise Drive-In real estate, intangible assets and restricted cash balances of $11.0 million. The 2016 Notes are secured by franchise fees, royalty payments and lease payments, and the repayment of the 2016 Notes is expected to be made solely from the income derived from the Co-Issuer’s assets. In addition, the Guarantor, a Sonic Corp. subsidiary that acts as a franchisor, has guaranteed the obligations of the Co-Issuers under the 2016 Notes and pledged substantially all of its assets to secure those obligations.

Neither Sonic Corp., the ultimate parent of the Co-Issuers and the Guarantor, nor any other subsidiary of Sonic, guarantees or in any way is liable for the obligations of the Co-Issuers under the 2016 Notes. The Company has, however, agreed to cause the performance of certain obligations of its subsidiaries, principally related to managing the assets included as collateral for the 2016 Notes and certain indemnity obligations relating to the transfer of the collateral assets to the Co-Issuers.

The 2016 Notes are subject to a series of covenants and restrictions similar to the Company’s 2011 Notes and customary for transactions of this type. If certain covenants or restrictions are not met, the 2016 Notes are subject to customary accelerated repayment events and events of default. Although management does not anticipate an event of default or any other event of noncompliance with the provisions of the debt, if such event occurred, the unpaid amounts outstanding could become immediately due and payable.

In connection with the 2016 transaction described above, the Company recognized an $8.8 million loss from the early extinguishment of debt during the third quarter of fiscal year 2016, which primarily consisted of a $5.9 million prepayment premium and the $2.9 million write-off of unamortized deferred loan fees remaining from the refinanced debt.