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

3 Months Ended

Dec. 27, 2019

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 U.S. 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.	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.	2021