Basis of Presentation and Summary of Significant Accounting Policies (Tables)

9 Months Ended

Jun. 26, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of New Accounting Pronouncements and Changes in Accounting Principles

A summary of recently adopted accounting guidance is as follows. Adoption dates are on the first day of the fiscal year indicated below, unless otherwise specified.

ASU	Description of ASU	Impact to Atkore	Note	Adoption Date
2016-02 Leases (Topic 842)	The Accounting Standards Update ("ASU") requires companies to use a "right of use" lease model that assumes that each lease creates an asset (the lessee's right to use the leased asset) and a liability (the future rent payment obligations), which should be reflected on a lessee's balance sheet to fairly represent the lease transaction and the lessee's related financial obligations with terms of more than 12 months.	The Company adopted the guidance in the first quarter of 2020 using the modified retrospective method. See Note 2, "Leases" for further detail.	2	2020

        A summary of accounting guidance not yet adopted is as follows. Effective dates are on the first day of the fiscal year indicated below, unless otherwise specified.

ASU	Description of ASU	Impact to Atkore	Effective Date
2016-13 Financial Instruments - Credit Losses (Topic 326)	The ASU adds to GAAP an impairment model (known as the current expected credit loss (CECL) model) that is based on expected losses rather than incurred losses. Under the new guidance, an entity recognizes as an allowance its estimate of expected credit losses, which the FASB believes will result in more timely recognition of such losses.	Under evaluation. Based on procedures performed to date, the Company does not anticipate the adoption of this ASU to be material to the financial statements.	2021
2018-14 Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans	The ASU amends Accounting Standards Codification ("ASC") 715 to add, remove and clarify disclosure requirements related to defined benefit pension and other postretirement plans.	Under evaluation. Based on procedures performed to date, the Company does not anticipate the adoption of this ASU to be material to the financial statements. The Company will be required to add a narrative description of the reasons for significant gains and losses affecting the benefit obligation for the period and will no longer be required to disclose the amounts in accumulated other comprehensive income expected to be recognized as part of net periodic benefit cost over the next year.	2021
2019-12 Income Tax	The ASU amends ASC 740 to simplify the accounting for various topics related to income taxes.	Under evaluation. Based on procedures performed to date, the Company does not anticipate the adoption of this ASU to be material to the financial statements.	2021
2020-04, Facilitation of the Effects of Reference Rate Reform on Financial Reporting (issued March 12, 2020)	The ASU addresses constituents’ concerns about certain accounting consequences that could result from the global markets’ anticipated transition away from the use of the London Interbank Offered Rate (LIBOR) and other interbank offered rates to alternative reference rates.	Under evaluation.	2022