Debt	9 Months Ended
May 31, 2018
Debt Disclosure [Abstract]
Debt	Debt During the second quarter of fiscal year 2018, the Company made a pro rata prepayment of $28.0 million on its 2013 Fixed Rate Notes and 2016 Fixed Rate Notes. The prepayment was made at par, as allowed under the note terms. On February 1, 2018, various subsidiaries of the Company (the “Co-Issuers”) issued $170.0 million of 2018 Fixed Rate Notes in a private transaction which bears interest at 4.03% per annum. The 2018 Fixed Rate Notes have an expected life of seven years with an anticipated repayment date in February 2025. At May 31, 2018, the balance outstanding under the 2018 Fixed Rate Notes including accrued interest totaled $170.2 million and carried a weighted-average interest cost of 4.40%, including the effect of the loan origination costs described below. Sonic used a portion of the net proceeds from the issuance of the 2018 Fixed Rate Notes to pay down the outstanding portion of the 2016 Variable Funding Notes and to pay the costs associated with the securitized financing transaction. In conjunction with the issuance of the 2018 Fixed Rate Notes, the commitments under the 2016 Variable Funding Notes were reduced to $100.0 million. Loan origination costs associated with the Company’s 2018 Fixed Rate Notes totaled $5.0 million. Loan costs are amortized over each note’s expected life, and the unamortized balance related to the 2016 Variable Funding Notes and the Fixed Rate Notes is included in debt origination costs, net and long-term debt, net, respectively, on the condensed consolidated balance sheets. In connection with the 2018 transactions described above, the Company recognized a $1.3 million loss during the second quarter of fiscal year 2018. The loss consisted of a $0.7 million write-off of unamortized deferred debt origination costs related to the reduction of the 2016 Variable Funding Notes commitments, as well as a $0.4 million write-off of unamortized deferred debt origination costs related to the prepayment on its 2013 Fixed Rate Notes and 2016 Fixed Rate Notes. Additionally, as required by the terms of the 2016 Fixed Rate Notes, the Company paid a $0.2 million prepayment premium. While the 2018 Fixed Rate Notes have an expected life of seven years, they have a legal final maturity date of February 2048. The Company intends to repay or refinance the 2018 Fixed Rate Notes on or before the end of their respective expected life. In the event the 2018 Fixed Rate Notes are not paid in full by the end of their expected life, 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, 2018, assets for these combined indirect subsidiaries totaled $255.2 million, including receivables for royalties, certain Company and Franchise Drive-In real estate, intangible assets and restricted cash balances of $28.5 million. The Notes are secured by franchise fees, royalty payments and lease payments, and the repayment of the 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 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 2018 Fixed Rate 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 2018 Fixed Rate Notes and certain indemnity obligations relating to the transfer of the collateral assets to the Co-Issuers. The 2018 Fixed Rate Notes are subject to a series of covenants and restrictions similar to the Company’s 2016 Fixed Rate Notes and customary for transactions of this type. If certain covenants or restrictions are not met, the 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.

Debt

During the second quarter of fiscal year 2018, the Company made a pro rata prepayment of $28.0 million on its 2013 Fixed Rate Notes and 2016 Fixed Rate Notes. The prepayment was made at par, as allowed under the note terms.

On February 1, 2018, various subsidiaries of the Company (the “Co-Issuers”) issued $170.0 million of 2018 Fixed Rate Notes in a private transaction which bears interest at 4.03% per annum. The 2018 Fixed Rate Notes have an expected life of seven years with an anticipated repayment date in February 2025. At May 31, 2018, the balance outstanding under the 2018 Fixed Rate Notes including accrued interest totaled $170.2 million and carried a weighted-average interest cost of 4.40%, including the effect of the loan origination costs described below.

Sonic used a portion of the net proceeds from the issuance of the 2018 Fixed Rate Notes to pay down the outstanding portion of the 2016 Variable Funding Notes and to pay the costs associated with the securitized financing transaction. In conjunction with the issuance of the 2018 Fixed Rate Notes, the commitments under the 2016 Variable Funding Notes were reduced to $100.0 million.

Loan origination costs associated with the Company’s 2018 Fixed Rate Notes totaled $5.0 million. Loan costs are amortized over each note’s expected life, and the unamortized balance related to the 2016 Variable Funding Notes and the Fixed Rate Notes is included in debt origination costs, net and long-term debt, net, respectively, on the condensed consolidated balance sheets.

In connection with the 2018 transactions described above, the Company recognized a $1.3 million loss during the second quarter of fiscal year 2018. The loss consisted of a $0.7 million write-off of unamortized deferred debt origination costs related to the reduction of the 2016 Variable Funding Notes commitments, as well as a $0.4 million write-off of unamortized deferred debt origination costs related to the prepayment on its 2013 Fixed Rate Notes and 2016 Fixed Rate Notes. Additionally, as required by the terms of the 2016 Fixed Rate Notes, the Company paid a $0.2 million prepayment premium.

While the 2018 Fixed Rate Notes have an expected life of seven years, they have a legal final maturity date of February 2048. The Company intends to repay or refinance the 2018 Fixed Rate Notes on or before the end of their respective expected life. In the event the 2018 Fixed Rate Notes are not paid in full by the end of their expected life, 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, 2018, assets for these combined indirect subsidiaries totaled $255.2 million, including receivables for royalties, certain Company and Franchise Drive-In real estate, intangible assets and restricted cash balances of $28.5 million. The Notes are secured by franchise fees, royalty payments and lease payments, and the repayment of the 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 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 2018 Fixed Rate 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 2018 Fixed Rate Notes and certain indemnity obligations relating to the transfer of the collateral assets to the Co-Issuers.

The 2018 Fixed Rate Notes are subject to a series of covenants and restrictions similar to the Company’s 2016 Fixed Rate Notes and customary for transactions of this type. If certain covenants or restrictions are not met, the 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.