Fair Value Of Financial Instruments	9 Months Ended
Sep. 30, 2021
Fair Value Of Financial Instruments [Abstract]
Fair Value Of Financial Instruments	4. Fair Value of Financial InstrumentsAssets and Liabilities Measured at Fair Value on a Recurring BasisThe carrying value of our cash and cash equivalents, restricted cash, accounts receivable and accounts payable approximate fair value because of their short-term nature. Our investments are comprised of U.S. Treasury securities, a corporate debt security, non-marketable equity securities, and an equity method investment. We also maintain a deferred compensation plan with related assets held in a rabbi trust. We designate the appropriate classification of our investments at the time of purchase based upon the intended holding period.Held-to-Maturity InvestmentsU.S. Treasury SecuritiesAs of September 30, 2021, we held $461,876 of U.S. Treasury securities with maturities of up to 20 months, of which $301,534 mature within one year. Our investments in U.S. Treasury securities are held at amortized cost. The fair value of our held-to-maturity U.S. Treasury security investments is measured using Level 1 inputs (quoted prices for identical assets in active markets). The amortized costs of these investments exceeded the fair value by $92 and $117 as of September 30, 2021 and December 31, 2020, respectively. We recognize a reserve for expected credit losses when lifetime credit losses are expected by management. As of September 30, 2021, management has concluded there is no risk of non-payment with respect to our U.S. Treasury security investments.Corporate Debt SecurityOn September 30, 2021, we acquired a promissory note issued by a supplier in exchange for $18,000. The promissory note has a principal balance of $18,000 and bears interest at a rate equal to the 3-month U.S. dollar LIBOR plus a fixed interest spread. Accrued interest is paid quarterly in arrears and principal is payable in accordance with an amortization schedule beginning on December 31, 2022. The promissory note matures on September 30, 2028. Our investment in the corporate debt security is held at amortized cost and approximates fair value as of September 30, 2021. As of September 30, 2021, we maintained a reserve of $423 for expected credit losses associated with the investment. Rabbi TrustWe maintain a rabbi trust to fund obligations under a deferred compensation plan. Amounts in the rabbi trust are invested in mutual funds, which are designated as trading securities carried at fair value and are included in other assets on the condensed consolidated balance sheets. Fair value of rabbi trust investments in mutual funds is measured using Level 1 inputs. The fair value of the investments in the rabbi trust was $18,669 and $15,296 as of September 30, 2021 and December 31, 2020, respectively. We record trading gains and losses in general and administrative expenses on the condensed consolidated statements of income and comprehensive income, along with the offsetting amount related to the increase or decrease in deferred compensation to reflect our exposure to liabilities for payment under the deferred plan. Assets and Liabilities Measured at Fair Value on a Nonrecurring BasisAssets recognized or disclosed at fair value on the condensed consolidated financial statements on a nonrecurring basis include items such as leasehold improvements, property and equipment, certain long-term investments, operating lease assets, other assets, and goodwill. These assets are measured at fair value whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The following table summarizes assets measured at fair value by hierarchy level on a nonrecurring basis for the periods indicated: Carrying Value September 30, Level2021 2020Leasehold improvements, property and equipment, net3$ 544 $ 3,427Operating lease assets3 2,857 7,113Total $ 3,401 $ 10,540Fair value of these assets was measured using Level 3 inputs (unobservable inputs for the asset or liability). Unobservable inputs include the discount rate, projected restaurant revenues and expenses, and sublease income if we are closing the restaurant. During the three months ended September 30, 2021 and 2020 we recorded asset impairments related to restaurants and offices of $240 and $2,935, respectively. During the nine months ended September 30, 2021 and 2020 we recorded asset impairments related to restaurants and offices of $3,468 and $12,965, respectively. Carrying value after the impairment charges approximates fair value. Non-Marketable Equity SecuritiesOn March 23, 2021, we acquired 766 shares of the Series C Preferred Stock of Nuro, Inc. (“Nuro”) in exchange for cash consideration of $10,000. Our investment represents a minority interest and we have determined that we do not have significant influence over Nuro. Nuro is a privately held company, and as such, the preferred shares comprising our investment are illiquid and their fair value is not readily determinable. We have elected to measure our investment in the non-marketable equity securities of Nuro at cost, less impairments, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer.Equity Method InvestmentOn April 16, 2020, we acquired approximately 10% of the common stock of a supplier in exchange for cash consideration of $7,500. On August 6, 2020, we acquired an additional 3.2% of the common stock of the same supplier in exchange for cash consideration of $2,500. As of September 30, 2021, we own approximately 12.7% of the supplier’s common stock and have invested total cash consideration of $10,000. As we are a significant customer of the supplier and maintain board representation, we are accounting for our investment under the equity method. The investment is included within other assets on the condensed consolidated balance sheet as of September 30, 2021, with a carrying value of $9,120. The investment would be impaired if the carrying value exceeds the fair value of the investment.

Fair Value Of Financial Instruments

9 Months Ended

Sep. 30, 2021

Fair Value Of Financial Instruments [Abstract]

4. Fair Value of Financial InstrumentsAssets and Liabilities Measured at Fair Value on a Recurring BasisThe carrying value of our cash and cash equivalents, restricted cash, accounts receivable and accounts payable approximate fair value because of their short-term nature. Our investments are comprised of U.S. Treasury securities, a corporate debt security, non-marketable equity securities, and an equity method investment. We also maintain a deferred compensation plan with related assets held in a rabbi trust. We designate the appropriate classification of our investments at the time of purchase based upon the intended holding period.Held-to-Maturity InvestmentsU.S. Treasury SecuritiesAs of September 30, 2021, we held $461,876 of U.S. Treasury securities with maturities of up to 20 months, of which $301,534 mature within one year. Our investments in U.S. Treasury securities are held at amortized cost. The fair value of our held-to-maturity U.S. Treasury security investments is measured using Level 1 inputs (quoted prices for identical assets in active markets). The amortized costs of these investments exceeded the fair value by $92 and $117 as of September 30, 2021 and December 31, 2020, respectively. We recognize a reserve for expected credit losses when lifetime credit losses are expected by management. As of September 30, 2021, management has concluded there is no risk of non-payment with respect to our U.S. Treasury security investments.Corporate Debt SecurityOn September 30, 2021, we acquired a promissory note issued by a supplier in exchange for $18,000. The promissory note has a principal balance of $18,000 and bears interest at a rate equal to the 3-month U.S. dollar LIBOR plus a fixed interest spread. Accrued interest is paid quarterly in arrears and principal is payable in accordance with an amortization schedule beginning on December 31, 2022. The promissory note matures on September 30, 2028. Our investment in the corporate debt security is held at amortized cost and approximates fair value as of September 30, 2021. As of September 30, 2021, we maintained a reserve of $423 for expected credit losses associated with the investment. Rabbi TrustWe maintain a rabbi trust to fund obligations under a deferred compensation plan. Amounts in the rabbi trust are invested in mutual funds, which are designated as trading securities carried at fair value and are included in other assets on the condensed consolidated balance sheets. Fair value of rabbi trust investments in mutual funds is measured using Level 1 inputs. The fair value of the investments in the rabbi trust was $18,669 and $15,296 as of September 30, 2021 and December 31, 2020, respectively. We record trading gains and losses in general and administrative expenses on the condensed consolidated statements of income and comprehensive income, along with the offsetting amount related to the increase or decrease in deferred compensation to reflect our exposure to liabilities for payment under the deferred plan. Assets and Liabilities Measured at Fair Value on a Nonrecurring BasisAssets recognized or disclosed at fair value on the condensed consolidated financial statements on a nonrecurring basis include items such as leasehold improvements, property and equipment, certain long-term investments, operating lease assets, other assets, and goodwill. These assets are measured at fair value whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The following table summarizes assets measured at fair value by hierarchy level on a nonrecurring basis for the periods indicated: Carrying Value September 30, Level2021 2020Leasehold improvements, property and equipment, net3$ 544 $ 3,427Operating lease assets3 2,857 7,113Total $ 3,401 $ 10,540Fair value of these assets was measured using Level 3 inputs (unobservable inputs for the asset or liability). Unobservable inputs include the discount rate, projected restaurant revenues and expenses, and sublease income if we are closing the restaurant. During the three months ended September 30, 2021 and 2020 we recorded asset impairments related to restaurants and offices of $240 and $2,935, respectively. During the nine months ended September 30, 2021 and 2020 we recorded asset impairments related to restaurants and offices of $3,468 and $12,965, respectively. Carrying value after the impairment charges approximates fair value. Non-Marketable Equity SecuritiesOn March 23, 2021, we acquired 766 shares of the Series C Preferred Stock of Nuro, Inc. (“Nuro”) in exchange for cash consideration of $10,000. Our investment represents a minority interest and we have determined that we do not have significant influence over Nuro. Nuro is a privately held company, and as such, the preferred shares comprising our investment are illiquid and their fair value is not readily determinable. We have elected to measure our investment in the non-marketable equity securities of Nuro at cost, less impairments, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer.Equity Method InvestmentOn April 16, 2020, we acquired approximately 10% of the common stock of a supplier in exchange for cash consideration of $7,500. On August 6, 2020, we acquired an additional 3.2% of the common stock of the same supplier in exchange for cash consideration of $2,500. As of September 30, 2021, we own approximately 12.7% of the supplier’s common stock and have invested total cash consideration of $10,000. As we are a significant customer of the supplier and maintain board representation, we are accounting for our investment under the equity method. The investment is included within other assets on the condensed consolidated balance sheet as of September 30, 2021, with a carrying value of $9,120. The investment would be impaired if the carrying value exceeds the fair value of the investment.