Significant Accounting Policies (Policies)	3 Months Ended
Nov. 30, 2019
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. 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, 2021. 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 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 will adopt the amendments as required in fiscal 2021. The provisions of ASU 2016-13 are not expected to have a material effect on our financial condition, results of operations, or cash flows. All other newly issued accounting pronouncements not yet effective have been deemed either immaterial or not applicable.
Fair Value Measurement	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. Revenue recognized from beginning balances of contract liabilities during the three months ended November 30, 2019 totaled $1.6 million. Unsatisfied performance obligations as of November 30, 2019 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)

3 Months Ended

Nov. 30, 2019

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.

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, 2021. 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 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 will adopt the amendments as required in fiscal 2021. The provisions of ASU 2016-13 are not expected to have a material effect on our financial condition, results of operations, or cash flows.

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

Fair Value Measurement

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. Revenue recognized from beginning balances of contract liabilities during the three months ended November 30, 2019 totaled $1.6 million.

Unsatisfied performance obligations as of November 30, 2019 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.