Employee Benefits	12 Months Ended
Aug. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Employee Benefits	Note 11 – Employee Benefits The Company and certain of its subsidiaries have or contribute to qualified and nonqualified retirement plans covering substantially all employees. These plans include a defined benefit pension plan, a supplemental executive retirement benefit plan (“SERBP”), multiemployer pension plans and defined contribution plans. Defined Benefit Pension Plan and Supplemental Executive Retirement Benefit Plan The Company maintains a qualified defined benefit pension plan for certain nonunion employees. Effective June 30, 2006, the Company froze this plan and ceased accruing further benefits for employee service. The Company reflects the funded status of the defined benefit pension plan as a net asset or liability in its Consolidated Balance Sheets. Changes in its funded status are recognized in comprehensive income. The Company amortizes as a component of net periodic pension benefit cost a portion of the net gain or loss reported within accumulated other comprehensive loss if the beginning-of-year net gain or loss exceeds 5% of the greater of the benefit obligation or the market value of plan assets. Net periodic pension benefit cost was not material for all periods presented in this report. The fair value of plan assets was $20 million and $17 million as of August 31, 2019 and 2018, respectively, and the projected benefit obligation was $17 million and $15 million as of August 31, 2019 and 2018, respectively. The plan was fully funded with the plan assets exceeding the projected benefit obligation by $3 million and $2 million as of August 31, 2019 and 2018, respectively. Plan assets comprised entirely Level 1 investments as of August 31, 2019 and 2018. Level 1 investments are valued based on quoted market prices of identical securities in the principal market. No contributions are expected to be made to the defined benefit pension plan in the future; however, changes in the discount rate or actual investment returns that are lower than the long-term expected return on plan assets could result in the need for the Company to make additional contributions. The assumed discount rate used to calculate the projected benefit obligation was 2.83% and 4.01% as of August 31, 2019 and 2018, respectively. The Company estimates future annual benefit payments to be between $1 million and $4 million per year. The Company also has a nonqualified SERBP for certain executives. A restricted trust fund has been established with assets invested in life insurance policies that can be used for plan benefits, although the fund is subject to claims of the Company’s general creditors. The trust fund is included in other assets, the current portion of the pension liability is included in other accrued liabilities, and the noncurrent portion of the pension liability is included in other long-term liabilities in the Company’s Consolidated Balance Sheets. The trust fund was valued at $4 million as of August 31, 2019 and 2018. The trust fund assets’ gains and losses are included in other income, net in the Company’s Consolidated Statements of Income. The benefit obligation and the unfunded amount were $5 million as of August 31, 2019 and $4 million as of August 31, 2018. Net periodic pension cost under the SERBP was not material for the years ended August 31, 2019, 2018 and 2017. Because the defined benefit pension plan and the SERBP are not material to the Consolidated Financial Statements, other disclosures required by U.S. GAAP have been omitted. Multiemployer Pension Plans The Company contributes to 14 multiemployer pension plans in accordance with its collective bargaining agreements. Multiemployer pension plans are defined benefit plans sponsored by multiple employers in accordance with one or more collective bargaining agreements. The plans are jointly managed by trustees that include representatives from both management and labor unions. Contributions to the plans are made based upon a fixed rate per hour worked and are agreed to by contributing employers and the unions in collective bargaining. Benefit levels are set by a joint board of trustees based on the advice of an independent actuary regarding the level of benefits that agreed-upon contributions can be expected to support. To the extent that the pension obligation of other participating employers is unfunded, the Company may be required to make additional contributions in the future to fund these obligations. One of the multiemployer plans that the Company contributes to is the Steelworkers Western Independent Shops Pension Plan (“WISPP,” EIN 90-0169564, Plan No. 001) benefiting the union employees of the Company’s steel manufacturing operations, which are covered by a collective bargaining agreement that will expire on March 31, 2022. As of October 1, 2018, the WISPP was certified by the plan’s actuaries as being in the Green Zone, as defined by the Pension Protection Act of 2006. The Company contributed $3 million to the WISPP for each of the years ended August 31, 2019, 2018 and 2017. These contributions represented more than 5% of total contributions to the WISPP for each year. In 2004, the Internal Revenue Service (“IRS”) approved a seven-year extension of the period over which the WISPP may amortize unfunded liabilities, conditioned upon maintenance of certain minimum funding levels. In 2014, the WISPP obtained relief from the specified funding requirements from the IRS, which requires that the WISPP meet a minimum funded percentage on each valuation date and achieve a funded percentage of 100% as of October 1, 2029. Based on the most recent actuarial valuation for the WISPP, the funded percentage using the valuation method prescribed by the IRS satisfied the minimum funded percentage requirement. Company contributions to all of the multiemployer plans were $6 million, $5 million and $4 million for the years ended August 31, 2019, 2018 and 2017, respectively. Defined Contribution Plans The Company has several defined contribution plans covering certain employees. Company contributions to the defined contribution plans totaled $4 million, $4 million and $3 million for the years ended August 31, 2019, 2018 and 2017, respectively.

Employee Benefits

12 Months Ended

Aug. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Note 11 – Employee Benefits

The Company and certain of its subsidiaries have or contribute to qualified and nonqualified retirement plans covering substantially all employees. These plans include a defined benefit pension plan, a supplemental executive retirement benefit plan (“SERBP”), multiemployer pension plans and defined contribution plans.

Defined Benefit Pension Plan and Supplemental Executive Retirement Benefit Plan

The Company maintains a qualified defined benefit pension plan for certain nonunion employees. Effective June 30, 2006, the Company froze this plan and ceased accruing further benefits for employee service. The Company reflects the funded status of the defined benefit pension plan as a net asset or liability in its Consolidated Balance Sheets. Changes in its funded status are recognized in comprehensive income. The Company amortizes as a component of net periodic pension benefit cost a portion of the net gain or loss reported within accumulated other comprehensive loss if the beginning-of-year net gain or loss exceeds 5% of the greater of the benefit obligation or the market value of plan assets. Net periodic pension benefit cost was not material for all periods presented in this report. The fair value of plan assets was $20 million and $17 million as of August 31, 2019 and 2018, respectively, and the projected benefit obligation was $17 million and $15 million as of August 31, 2019 and 2018, respectively. The plan was fully funded with the plan assets exceeding the projected benefit obligation by $3 million and $2 million as of August 31, 2019 and 2018, respectively. Plan assets comprised entirely Level 1 investments as of August 31, 2019 and 2018. Level 1 investments are valued based on quoted market prices of identical securities in the principal market. No contributions are expected to be made to the defined benefit pension plan in the future; however, changes in the discount rate or actual investment returns that are lower than the long-term expected return on plan assets could result in the need for the Company to make additional contributions. The assumed discount rate used to calculate the projected benefit obligation was 2.83% and 4.01% as of August 31, 2019 and 2018, respectively. The Company estimates future annual benefit payments to be between $1 million and $4 million per year.

The Company also has a nonqualified SERBP for certain executives. A restricted trust fund has been established with assets invested in life insurance policies that can be used for plan benefits, although the fund is subject to claims of the Company’s general creditors. The trust fund is included in other assets, the current portion of the pension liability is included in other accrued liabilities, and the noncurrent portion of the pension liability is included in other long-term liabilities in the Company’s Consolidated Balance Sheets. The trust fund was valued at $4 million as of August 31, 2019 and 2018. The trust fund assets’ gains and losses are included in other income, net in the Company’s Consolidated Statements of Income. The benefit obligation and the unfunded amount were $5 million as of August 31, 2019 and $4 million as of August 31, 2018. Net periodic pension cost under the SERBP was not material for the years ended August 31, 2019, 2018 and 2017.

Because the defined benefit pension plan and the SERBP are not material to the Consolidated Financial Statements, other disclosures required by U.S. GAAP have been omitted.

Multiemployer Pension Plans

The Company contributes to 14 multiemployer pension plans in accordance with its collective bargaining agreements. Multiemployer pension plans are defined benefit plans sponsored by multiple employers in accordance with one or more collective bargaining agreements. The plans are jointly managed by trustees that include representatives from both management and labor unions. Contributions to the plans are made based upon a fixed rate per hour worked and are agreed to by contributing employers and the unions in collective bargaining. Benefit levels are set by a joint board of trustees based on the advice of an independent actuary regarding the level of benefits that agreed-upon contributions can be expected to support. To the extent that the pension obligation of other participating employers is unfunded, the Company may be required to make additional contributions in the future to fund these obligations.

One of the multiemployer plans that the Company contributes to is the Steelworkers Western Independent Shops Pension Plan (“WISPP,” EIN 90-0169564, Plan No. 001) benefiting the union employees of the Company’s steel manufacturing operations, which are covered by a collective bargaining agreement that will expire on March 31, 2022. As of October 1, 2018, the WISPP was certified by the plan’s actuaries as being in the Green Zone, as defined by the Pension Protection Act of 2006. The Company contributed $3 million to the WISPP for each of the years ended August 31, 2019, 2018 and 2017. These contributions represented more than 5% of total contributions to the WISPP for each year.

In 2004, the Internal Revenue Service (“IRS”) approved a seven-year extension of the period over which the WISPP may amortize unfunded liabilities, conditioned upon maintenance of certain minimum funding levels. In 2014, the WISPP obtained relief from the specified funding requirements from the IRS, which requires that the WISPP meet a minimum funded percentage on each valuation date and achieve a funded percentage of 100% as of October 1, 2029. Based on the most recent actuarial valuation for the WISPP, the funded percentage using the valuation method prescribed by the IRS satisfied the minimum funded percentage requirement.

Company contributions to all of the multiemployer plans were $6 million, $5 million and $4 million for the years ended August 31, 2019, 2018 and 2017, respectively.

Defined Contribution Plans

The Company has several defined contribution plans covering certain employees. Company contributions to the defined contribution plans totaled $4 million, $4 million and $3 million for the years ended August 31, 2019, 2018 and 2017, respectively.