Contingencies	9 Months Ended
May 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Litigation As reported in the Annual Report on Form 10-K for the year ended August 31, 2017, the Company was named as a defendant in five purported class action complaints related to a payment card breach at certain Sonic Drive-Ins. The Company has since been named as a defendant in four additional purported class action complaints filed on October 9, 2017, in the United States District Court for the Northern District of Ohio, on November 3, 2017, in the United States District Court for the Northern District of Texas, on November 13, 2017, in the United States District Court for the District of Arizona, and on December 17, 2017, in the Northern District of Illinois. Each of these complaints asserted various claims related to the Company’s alleged failure to safeguard customer credit card information, and the plaintiffs sought monetary damages, injunctive and declaratory relief and attorneys’ fees and costs. The cases were centralized in the Northern District of Ohio for coordinated or consolidated pretrial proceedings, and a consolidated complaint was filed. The Company believes it has meritorious defenses to the litigation and intends to vigorously oppose the claims asserted in the complaint. We cannot reasonably estimate the range of potential losses that may be associated with the litigation because of the early stage of the lawsuit. We also cannot provide assurance we will not become subject to other inquiries or claims relating to the payment card breach in the future. Although we maintain cyber liability insurance, we currently believe it is possible the ultimate amount paid by us, if we are unsuccessful in defending the litigation, will be in excess of our cyber liability insurance coverage applicable to claims of this nature. We are unable to estimate the amount of any such excess. The Company is involved in various other legal proceedings and has certain unresolved claims pending. Based on the information currently available, management believes all such other claims currently pending are either covered by insurance or would not have a material adverse effect on the Company’s business or financial condition. Note Repurchase Agreement On December 20, 2013, the Company extended a note purchase agreement to a bank that serves to guarantee the repayment of a franchisee loan, with a term through 2018. In the event of default by the franchisee, the Company would purchase the franchisee loan from the bank, thereby becoming the note holder and providing an avenue of recourse with the franchisee. The Company recorded a liability for this guarantee which was based on the Company’s estimate of fair value. As of May 31, 2018, the balance of the franchisee’s loan was $5.2 million. Lease Commitments The Company has obligations under various operating lease agreements with third-party lessors related to the real estate for certain Company Drive-In operations that were sold to franchisees. Under these agreements, which expire through 2029, the Company remains secondarily liable for the lease payments for which it was responsible as the original lessee. As of May 31, 2018, the amount remaining under these guaranteed lease obligations totaled $15.4 million. At this time, the Company does not anticipate any material defaults under the foregoing leases; therefore, zero liability has been provided.

Contingencies

Litigation

As reported in the Annual Report on Form 10-K for the year ended August 31, 2017, the Company was named as a defendant in five purported class action complaints related to a payment card breach at certain Sonic Drive-Ins. The Company has since been named as a defendant in four additional purported class action complaints filed on October 9, 2017, in the United States District Court for the Northern District of Ohio, on November 3, 2017, in the United States District Court for the Northern District of Texas, on November 13, 2017, in the United States District Court for the District of Arizona, and on December 17, 2017, in the Northern District of Illinois. Each of these complaints asserted various claims related to the Company’s alleged failure to safeguard customer credit card information, and the plaintiffs sought monetary damages, injunctive and declaratory relief and attorneys’ fees and costs. The cases were centralized in the Northern District of Ohio for coordinated or consolidated pretrial proceedings, and a consolidated complaint was filed. The Company believes it has meritorious defenses to the litigation and intends to vigorously oppose the claims asserted in the complaint. We cannot reasonably estimate the range of potential losses that may be associated with the litigation because of the early stage of the lawsuit. We also cannot provide assurance we will not become subject to other inquiries or claims relating to the payment card breach in the future. Although we maintain cyber liability insurance, we currently believe it is possible the ultimate amount paid by us, if we are unsuccessful in defending the litigation, will be in excess of our cyber liability insurance coverage applicable to claims of this nature. We are unable to estimate the amount of any such excess.

The Company is involved in various other legal proceedings and has certain unresolved claims pending. Based on the information currently available, management believes all such other claims currently pending are either covered by insurance or would not have a material adverse effect on the Company’s business or financial condition.

Note Repurchase Agreement

On December 20, 2013, the Company extended a note purchase agreement to a bank that serves to guarantee the repayment of a franchisee loan, with a term through 2018. In the event of default by the franchisee, the Company would purchase the franchisee loan from the bank, thereby becoming the note holder and providing an avenue of recourse with the franchisee. The Company recorded a liability for this guarantee which was based on the Company’s estimate of fair value. As of May 31, 2018, the balance of the franchisee’s loan was $5.2 million.

Lease Commitments

The Company has obligations under various operating lease agreements with third-party lessors related to the real estate for certain Company Drive-In operations that were sold to franchisees. Under these agreements, which expire through 2029, the Company remains secondarily liable for the lease payments for which it was responsible as the original lessee. As of May 31, 2018, the amount remaining under these guaranteed lease obligations totaled $15.4 million. At this time, the Company does not anticipate any material defaults under the foregoing leases; therefore, zero liability has been provided.