Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Feb. 28, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying Unaudited Condensed Consolidated Financial Statements of Schnitzer Steel Industries, Inc. (the “Company”) have been prepared pursuant to generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim financial information and the rules and regulations of the United States Securities and Exchange Commission (the “SEC”) for Form 10-Q, including Article 10 of Regulation S-X. The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. Certain information and note disclosures normally included in annual financial statements have been condensed or omitted pursuant to the rules and regulations of the SEC. In the opinion of management, all normal, recurring adjustments considered necessary for a fair statement have been included. Management suggests that these Unaudited Condensed Consolidated Financial Statements be read in conjunction with the financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended August 31, 2018. The results for the three and six months ended February 28, 2019 and 2018 are not necessarily indicative of the results of operations for the entire fiscal year. Accounting Changes As of the beginning of the first quarter of fiscal 2019, the Company adopted an accounting standards update initially issued in May 2014 that clarifies the principles for recognizing revenue from contracts with customers. The core principle of the new guidance is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to in exchange for those goods or services. The Company adopted the new revenue accounting standard using the modified retrospective approach, which requires recognition of the cumulative effect of initially applying the new requirements as an adjustment to the opening balance of retained earnings in the period of initial application. Adoption of the new requirements did not change the timing of revenue recognition for the Company compared to the previous guidance, and the Company recorded no cumulative-effect adjustment to the opening balance of retained earnings as of September 1, 2018. The Company identified certain scrap purchase and sale arrangements for which it recognized revenue for the gross amount of consideration it expected to be entitled to from the customer (as principal) under the previous revenue guidance, but for which under the new revenue standard it recognizes revenue as the net amount of consideration that it expects to retain after paying the scrap metal supplier (as agent). The foregoing change in the classification of the cost of scrap metal purchased under such arrangements has the effect of reducing the amount of revenue and cost of goods sold reported in the financial statements, while having no impact on net income. If the Company had continued using the accounting guidance in effect before the adoption of the new revenue accounting standard, its consolidated revenues for the three and six months ended February 28, 2019 would have been higher by approximately $7 million and $13 million, respectively, or 1% for each period, and its consolidated cost of goods sold would have been higher by the same amounts, respectively. No other line items in the consolidated financial statements were materially impacted by adoption of the new requirements. Comparative prior period amounts and disclosures continue to be reported in accordance with guidance in effect prior to the date of adoption. See Note 7 - Revenue for the disclosures required under the new standard. As of the beginning of the first quarter of fiscal 2019, the Company adopted an accounting standards update that amends certain aspects of the reporting model for financial instruments. The most pertinent amendment to the Company is that an entity may choose to measure certain equity investments that do not have readily determinable fair values at cost minus impairment, plus or minus changes resulting from observable price changes. The amendments also require a qualitative assessment to identify impairment of equity investments without readily determinable fair values. Adoption of the requirements had no impact on the Company’s consolidated financial position, results of operations and cash flows. Cash and Cash Equivalents Cash and cash equivalents include short-term securities that are not restricted by third parties and have an original maturity date of 90 days or less. Included in accounts payable are book overdrafts representing outstanding checks in excess of funds on deposit of $27 million and $28 million as of February 28, 2019 and August 31, 2018, respectively. Accounts Receivable, net Accounts receivable represent amounts primarily due from customers on product and other sales. These accounts receivable, which are reduced by an allowance for doubtful accounts, are recorded at the invoiced amount and do not bear interest. The Company extends credit to customers under contracts containing customary and explicit payment terms, and payment is generally required within 30 days of shipment. Nonferrous export sales typically require a deposit prior to shipment. Historically, almost all of the Company’s ferrous export sales have been made with letters of credit. Domestic ferrous metal sales, nonferrous metal sales and finished steel sales are generally made on open account, and the majority of these sales are covered by credit insurance. The Company evaluates the collectibility of its accounts receivable based on a combination of factors, including whether sales were made pursuant to letters of credit or credit insurance is in place. In cases where management is aware of circumstances that may impair a customer’s ability to meet its financial obligations, management records a specific allowance against amounts due and reduces the receivable to the amount the Company believes will be collected. For all other customers, the Company maintains an allowance that considers the total receivables outstanding, historical collection rates and economic trends. Accounts are written off when all efforts to collect have been exhausted. Also included in accounts receivable are short-term advances to scrap metal suppliers used as a mechanism to acquire unprocessed scrap metal. The advances are generally repaid with scrap metal, as opposed to cash. Repayments of advances with scrap metal are treated as noncash operating activities in the Unaudited Condensed Consolidated Statements of Cash Flows and totaled $8 million and $6 million for the six months ended February 28, 2019 and 2018, respectively. Prepaid Expenses The Company’s prepaid expenses totaled $14 million and $22 million as of February 28, 2019 and August 31, 2018, respectively, and consisted primarily of deposits on capital purchases, prepaid services and prepaid insurance. Other Assets The Company’s other assets, exclusive of prepaid expenses, consist primarily of receivables from insurers, an equity investment, debt issuance costs, and notes and other contractual receivables. Other assets are reported within either prepaid expenses and other current assets or other assets in the Unaudited Condensed Consolidated Balance Sheets based on their expected use either during or beyond the current operating cycle of one year from the reporting date. Receivables from insurers totaled $15 million and $36 million as of February 28, 2019 and August 31, 2018, respectively, with the decrease in the first half of fiscal 2019 resulting from the settlement of a contingent loss recorded during fiscal 2018 in connection with lawsuits arising from a motor vehicle collision for which the Company had insurance coverage. See “Contingencies – Other” in Note 5 – Commitments and Contingencies for further discussion of the contingent loss and subsequent settlements in fiscal 2019. The Company previously invested $6 million in a privately-held waste and recycling entity. The investment does not have a readily determinable fair value and, therefore, is carried at cost and adjusted for impairments and observable price changes. The investment is presented as part of the Auto and Metals Recycling (“AMR”) reportable segment and reported within other assets in the Unaudited Condensed Consolidated Balance Sheets. The carrying value of the investment was $6 million as of February 28, 2019 and August 31, 2018. The Company has not recorded any impairments or upward or downward adjustments to the carrying value of the investment since acquisition. Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents, accounts receivable, and notes and other contractual receivables. The majority of cash and cash equivalents is maintained with major financial institutions. Balances with these and certain other institutions exceeded the Federal Deposit Insurance Corporation insured amount of $250,000 as of February 28, 2019. Concentration of credit risk with respect to accounts receivable is limited because a large number of geographically diverse customers make up the Company’s customer base. The Company controls credit risk through credit approvals, limits, insurance, letters of credit or other collateral, cash deposits and monitoring procedures. The Company is exposed to a residual credit risk with respect to open letters of credit by virtue of the possibility of the failure of a bank providing a letter of credit. The Company had $60 million and $58 million of open letters of credit as of February 28, 2019 and August 31, 2018, respectively.