Significant Accounting Policies (Policies)	3 Months Ended
Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The accompanying (a) consolidated balance sheet as of September 30, 2023, which has been derived from audited financial statements, and (b) unaudited interim consolidated financial statements as of and for the three months ended December 31, 2023 have been prepared by the Company in accordance with accounting principles generally accepted in the United States of America for interim financial information, pursuant to the rules and regulations of the Securities and Exchange Commission. In the opinion of management, the consolidated financial statements include all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the financial position, results of operations, and cash flows of the interim periods presented. Operating results for the interim periods presented are not necessarily indicative of results to be expected for the full year or for any other interim period, due to variability in customer purchasing patterns, seasonality, and other factors. These consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended September 30, 2023. In preparation of the Company’s consolidated financial statements, management is required to make estimates and assumptions that affect reported amounts of assets and liabilities and related revenues and expenses during the reporting periods. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates.
Consolidation, Policy [Policy Text Block]	Principles of Consolidation The consolidated financial statements include the accounts of Clearfield, Inc. and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Adopted Accounting Pronouncements On October 1, 2023, the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standard Update (“ASU”) No. 2016-13, Measurement of Credit Losses on Financial Instruments, and subsequent amendments to the initial guidance: ASU No. 2018-19, ASU No. 2019-04, ASU No. 2019-05, and ASU No. 2020-02 (collectively, Topic 326). This guidance introduces a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses (CECL). The measurement of expected credit losses under the CECL methodology is applicable to financial assets measured at amortized cost. The Company adopted Topic 326 using the modified retrospective method for all financial assets measured at amortized cost, which are primarily trade accounts receivable for the Company. Results for reporting periods beginning after October 1, 2023, are presented under Topic 326 while prior period amounts continue to be reported in accordance with previously applicable U.S. GAAP. The impact of adopting Topic 326 as of October 1, 2023, was not material to the consolidated financial statements.

Significant Accounting Policies (Policies)

3 Months Ended

Dec. 31, 2023

Basis of Accounting, Policy [Policy Text Block]

Basis of Presentation

The accompanying (a) consolidated balance sheet as of September 30, 2023, which has been derived from audited financial statements, and (b) unaudited interim consolidated financial statements as of and for the three months ended December 31, 2023 have been prepared by the Company in accordance with accounting principles generally accepted in the United States of America for interim financial information, pursuant to the rules and regulations of the Securities and Exchange Commission. In the opinion of management, the consolidated financial statements include all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the financial position, results of operations, and cash flows of the interim periods presented. Operating results for the interim periods presented are not necessarily indicative of results to be expected for the full year or for any other interim period, due to variability in customer purchasing patterns, seasonality, and other factors. These consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended September 30, 2023.

In preparation of the Company’s consolidated financial statements, management is required to make estimates and assumptions that affect reported amounts of assets and liabilities and related revenues and expenses during the reporting periods. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates.

Consolidation, Policy [Policy Text Block]

Principles of Consolidation

The consolidated financial statements include the accounts of Clearfield, Inc. and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Adopted Accounting Pronouncements

On October 1, 2023, the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standard Update (“ASU”) No. 2016-13, Measurement of Credit Losses on Financial Instruments, and subsequent amendments to the initial guidance: ASU No. 2018-19, ASU No. 2019-04, ASU No. 2019-05, and ASU No. 2020-02 (collectively, Topic 326). This guidance introduces a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses (CECL). The measurement of expected credit losses under the CECL methodology is applicable to financial assets measured at amortized cost. The Company adopted Topic 326 using the modified retrospective method for all financial assets measured at amortized cost, which are primarily trade accounts receivable for the Company. Results for reporting periods beginning after October 1, 2023, are presented under Topic 326 while prior period amounts continue to be reported in accordance with previously applicable U.S. GAAP. The impact of adopting Topic 326 as of October 1, 2023, was not material to the consolidated financial statements.