Significant Accounting Policies (Policies)	9 Months Ended
May 31, 2020
Accounting Policies [Abstract]
Basis of Accounting	We prepared the Consolidated Financial Statements in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) to present the financial position, results of operations, and cash flows of Acuity Brands and its wholly-owned subsidiaries.
Use of Estimates	Use of Estimates The preparation of financial statements and related disclosures in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates.
Reclassifications	Reclassifications Certain prior-period amounts have been reclassified to conform to the current year presentation. No material reclassifications occurred during the current period.
New Accounting Pronouncements	New Accounting Pronouncements Accounting Standards Adopted in Fiscal 2020 Accounting Standards Codification (“ASC”) 842 — Leases (“ASC 842”) In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (“ASU 2016-02”), which requires lessees to include most leases on the balance sheet as lease liabilities with an associated right-of-use (“ROU”) asset. Since the issuance of ASU 2016-02, the FASB released several amendments to improve and clarify the implementation guidance, as well as to change the allowable adoption methods. These standards have been collectively codified within ASC 842, Leases (“ASC 842”). We adopted ASC 842 using the modified retrospective method and applied the standard to all leases existing as of September 1, 2019. Information for prior years presented has not been restated and continues to reflect the authoritative accounting standards in effect for those periods. We elected the package of transition practical expedients that allows us to carryforward our historical assessments of whether existing contracts contain leases, determinations of lease classification, and treatments of initial direct costs. As of September 1, 2019, we recognized total operating lease liabilities of $64.7 million in our Consolidated Balance Sheets, of which $49.3 million was recorded within Long-term operating lease liabilities and $15.4 million was recorded within Current operating lease liabilities. We additionally derecognized $5.1 million of previously recorded net deferred rent balances and recorded ROU assets of $59.6 million related to our operating leases, which were reflected within Operating lease right-of-use assets in our Consolidated Balance Sheets. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”), which provides optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by the discontinuation of the London Interbank Offered Rate (“LIBOR”) or by another reference rate expected to be discontinued. The amendments are effective for all entities as of March 12, 2020 and expire on December 31, 2022. The provisions of ASU 2020-04 did not have a material effect on our financial condition, results of operations, and cash flows as of May 31, 2020. We will continue to monitor any impacts of reference rate reform on our financial instruments. Accounting Standards Yet to Be Adopted In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes, eliminates certain exceptions within ASC 740, Income Taxes, and clarifies certain aspects of the current guidance to promote consistency among reporting entities. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020. Most amendments within the standard are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. We are currently evaluating the impacts of the provisions of ASU 2019-12 on our financial condition, results of operations, and cash flows. In August 2018, the FASB issued ASU No. 2018-15, Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract (“ASU 2018-15”), which will require customers to apply internal-use software guidance to determine the implementation costs that are able to be capitalized. Capitalized implementation costs will be required to be amortized over the term of the arrangement, beginning when the cloud computing arrangement is ready for its intended use. ASU 2018-15 is effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2019. The standard allows changes to be applied either retrospectively or prospectively. We will adopt the standard as required in fiscal 2021. The provisions of ASU 2018-15 are not expected to have a material effect on our financial condition, results of operations, or cash flows. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires an entity to assess impairment of its financial instruments based on its estimate of expected credit losses. Since the issuance of ASU 2016-13, the FASB released several amendments to improve and clarify the implementation guidance. The provisions of ASU 2016-13 and the related amendments are effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2019. Entities are required to apply these changes through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. We have an implementation team tasked with reviewing our financial assets and determining the impact of the new standard to our financial statements. The team is also tasked with identifying appropriate changes to our business processes, systems, and controls to support recognition and disclosure under the new standard. The implementation team has completed its review of our current portfolio of financial assets and is currently assessing the potential impacts of the new standard. Our current financial asset portfolio consists primarily of trade receivables, and we expect the application of the expected credit loss model will have an immaterial impact on our trade receivable allowances. The implementation team reports its findings and progress of the project to management on a frequent basis and to the Audit Committee of the Board of Directors on a quarterly basis. We will adopt the amendments as required in fiscal 2021. All other newly issued accounting pronouncements not yet effective have been deemed either immaterial or not applicable.
Fair Value Measurement	We determine fair value measurements based on the assumptions a market participant would use in pricing an asset or liability. ASC 820, Fair Value Measurements and Disclosures (“ASC 820”), establishes a three-level hierarchy that categorizes market participant assumptions based on (i) unadjusted quoted prices for identical assets or liabilities in an active market (Level 1), (ii) quoted prices in markets that are not active or inputs that are observable either directly or indirectly for substantially the full term of the asset or liability (Level 2), and (iii) prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement (Level 3). We utilize valuation methodologies to determine the fair values of our financial assets and liabilities in conformity with the concepts of “exit price” and the fair value hierarchy as prescribed in ASC 820. All valuation methods and assumptions are validated at least quarterly to ensure the accuracy and relevance of the fair values. There were no material changes to the valuation methods or assumptions used to determine fair values during the current period.
Fair Value Transfers	We used quoted market prices to determine the fair value of Level 1 assets and liabilities. No transfers between the levels of the fair value hierarchy occurred during the current fiscal period. In the event of a transfer in or out of a level within the fair value hierarchy, the transfers would be recognized on the date of occurrence.
Revenue Recognition	Current deferred revenues primarily consist of software licenses as well as professional service and sales-type warranty fees collected prior to performing the related service. Current deferred revenues are included within Other current liabilities on the Consolidated Balance Sheets. These services are expected to be performed within one year. Non-current deferred revenues primarily consist of long-term service-type warranties, which are typically recognized ratably as revenue between five and ten years from the date of sale, and are included within Other long-term liabilities on the Consolidated Balance Sheets. Unsatisfied performance obligations as of May 31, 2020 that do not represent contract liabilities consist primarily of orders for physical goods that have not yet been shipped, which are typically shipped within a few weeks of order receipt. Disaggregated Revenues Our lighting and building management solutions are sold primarily through independent sales agents who cover specific geographic areas and market channels, by internal sales representatives, through consumer retail channels, and directly to large corporate accounts. We recognize revenue when we transfer control of goods and services to our customers. Revenue is measured as the amount of consideration we expect to receive in exchange for goods and services and is recognized net of allowances for rebates, sales incentives, product returns, and discounts to customers. Further details regarding revenue recognition are included within the Revenue Recognition footnote of the Notes to Consolidated Financial Statements within our Form 10-K. Contract Balances Our rights related to collections from customers are unconditional and are reflected within Accounts receivable on the Consolidated Balance Sheets. We do not have any other significant contract assets. Contract liabilities arise when we receive cash or an unconditional right to collect cash prior to the transfer of control of goods or services.

Significant Accounting Policies (Policies)

9 Months Ended

May 31, 2020

We prepared the Consolidated Financial Statements in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) to present the financial position, results of operations, and cash flows of Acuity Brands and its wholly-owned subsidiaries.

Use of Estimates

The preparation of financial statements and related disclosures in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates.

Reclassifications

Certain prior-period amounts have been reclassified to conform to the current year presentation. No material reclassifications occurred during the current period.

New Accounting Pronouncements

Accounting Standards Adopted in Fiscal 2020

Accounting Standards Codification (“ASC”) 842 — Leases (“ASC 842”)

In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (“ASU 2016-02”), which requires lessees to include most leases on the balance sheet as lease liabilities with an associated right-of-use (“ROU”) asset. Since the issuance of ASU 2016-02, the FASB released several amendments to improve and clarify the implementation guidance, as well as to change the allowable adoption methods. These standards have been collectively codified within ASC 842, Leases (“ASC 842”).

We adopted ASC 842 using the modified retrospective method and applied the standard to all leases existing as of September 1, 2019. Information for prior years presented has not been restated and continues to reflect the authoritative accounting standards in effect for those periods. We elected the package of transition practical expedients that allows us to carryforward our historical assessments of whether existing contracts contain leases, determinations of lease classification, and treatments of initial direct costs.

As of September 1, 2019, we recognized total operating lease liabilities of $64.7 million in our Consolidated Balance Sheets, of which $49.3 million was recorded within Long-term operating lease liabilities and $15.4 million was recorded within Current operating lease liabilities. We additionally derecognized $5.1 million of previously recorded net deferred rent balances and recorded ROU assets of $59.6 million related to our operating leases, which were reflected within Operating lease right-of-use assets in our Consolidated Balance Sheets.

In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”), which provides optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by the discontinuation of the London Interbank Offered Rate (“LIBOR”) or by another reference rate expected to be discontinued. The amendments are effective for all entities as of March 12, 2020 and expire on December 31, 2022. The provisions of ASU 2020-04 did not have a material effect on our financial condition, results of operations, and cash flows as of May 31, 2020. We will continue to monitor any impacts of reference rate reform on our financial instruments.

Accounting Standards Yet to Be Adopted

In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes, eliminates certain exceptions within ASC 740, Income Taxes, and clarifies certain aspects of the current guidance to promote consistency among reporting entities. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020. Most amendments within the standard are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. We are currently evaluating the impacts of the provisions of ASU 2019-12 on our financial condition, results of operations, and cash flows.

In August 2018, the FASB issued ASU No. 2018-15, Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract (“ASU 2018-15”), which will require customers to apply internal-use software guidance to determine the implementation costs that are able to be capitalized. Capitalized implementation costs will be required to be amortized over the term of the arrangement, beginning when the cloud computing arrangement is ready for its intended use. ASU 2018-15 is effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2019. The standard allows changes to be applied either retrospectively or prospectively. We will adopt the standard as required in fiscal 2021. The provisions of ASU 2018-15 are not expected to have a material effect on our financial condition, results of operations, or cash flows.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires an entity to assess impairment of its financial instruments based on its estimate of expected credit losses. Since the issuance of ASU 2016-13, the FASB released several amendments to improve and clarify the implementation guidance. The provisions of ASU 2016-13 and the related amendments are effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2019. Entities are required to apply these changes through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective.

We have an implementation team tasked with reviewing our financial assets and determining the impact of the new standard to our financial statements. The team is also tasked with identifying appropriate changes to our business processes, systems, and controls to support recognition and disclosure under the new standard. The implementation team has completed its review of our current portfolio of financial assets and is currently assessing the potential impacts of the new standard. Our current financial asset portfolio consists primarily of trade receivables, and we expect the application of the expected credit loss model will have an immaterial impact on our trade receivable allowances. The implementation team reports its findings and progress of the project to management on a frequent basis and to the Audit Committee of the Board of Directors on a quarterly basis. We will adopt the amendments as required in fiscal 2021.

All other newly issued accounting pronouncements not yet effective have been deemed either immaterial or not applicable.

Fair Value Measurement

We determine fair value measurements based on the assumptions a market participant would use in pricing an asset or liability. ASC 820, Fair Value Measurements and Disclosures (“ASC 820”), establishes a three-level hierarchy that categorizes market participant assumptions based on (i) unadjusted quoted prices for identical assets or liabilities in an active market (Level 1), (ii) quoted prices in markets that are not active or inputs that are observable either directly or indirectly for substantially the full term of the asset or liability (Level 2), and (iii) prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement (Level 3).

We utilize valuation methodologies to determine the fair values of our financial assets and liabilities in conformity with the concepts of “exit price” and the fair value hierarchy as prescribed in ASC 820. All valuation methods and assumptions are validated at least quarterly to ensure the accuracy and relevance of the fair values. There were no material changes to the valuation methods or assumptions used to determine fair values during the current period.

Fair Value Transfers

We used quoted market prices to determine the fair value of Level 1 assets and liabilities. No transfers between the levels of the fair value hierarchy occurred during the current fiscal period. In the event of a transfer in or out of a level within the fair value hierarchy, the transfers would be recognized on the date of occurrence.

Revenue Recognition

Current deferred revenues primarily consist of software licenses as well as professional service and sales-type warranty fees collected prior to performing the related service. Current deferred revenues are included within Other current liabilities on the Consolidated Balance Sheets. These services are expected to be performed within one year. Non-current deferred revenues primarily consist of long-term service-type warranties, which are typically recognized ratably as revenue between five and ten years from the date of sale, and are included within Other long-term liabilities on the Consolidated Balance Sheets.

Unsatisfied performance obligations as of May 31, 2020 that do not represent contract liabilities consist primarily of orders for physical goods that have not yet been shipped, which are typically shipped within a few weeks of order receipt.

Disaggregated Revenues

Our lighting and building management solutions are sold primarily through independent sales agents who cover specific geographic areas and market channels, by internal sales representatives, through consumer retail channels, and directly to large corporate accounts.

We recognize revenue when we transfer control of goods and services to our customers. Revenue is measured as the amount of consideration we expect to receive in exchange for goods and services and is recognized net of allowances for rebates, sales incentives, product returns, and discounts to customers. Further details regarding revenue recognition are included within the Revenue Recognition footnote of the Notes to Consolidated Financial Statements within our Form 10-K.

Contract Balances

Our rights related to collections from customers are unconditional and are reflected within Accounts receivable on the Consolidated Balance Sheets. We do not have any other significant contract assets. Contract liabilities arise when we receive cash or an unconditional right to collect cash prior to the transfer of control of goods or services.