SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Apr. 30, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Basis of Presentation [Text Block]	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of HEICO Corporation and its subsidiaries (collectively, “HEICO,” or the “Company”) have been prepared in conformity with accounting principles generally accepted in the United States of America for interim financial information and in accordance with the instructions to Form 10-Q. Therefore, the condensed consolidated financial statements do not include all information and footnotes normally included in annual consolidated financial statements and 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 October 31, 2019. The October 31, 2019 Condensed Consolidated Balance Sheet has been derived from the Company’s audited consolidated financial statements. In the opinion of management, the unaudited condensed consolidated financial statements contain all adjustments (consisting principally of normal recurring accruals) necessary for a fair presentation of the condensed consolidated balance sheets, statements of operations, statements of comprehensive income, statements of shareholders' equity and statements of cash flows for such interim periods presented. The results of operations for the six months ended April 30, 2020 are not necessarily indicative of the results which may be expected for the entire fiscal year. The Company has two operating segments: the Flight Support Group (“FSG”), consisting of HEICO Aerospace Holdings Corp. and HEICO Flight Support Corp. and their respective subsidiaries; and the Electronic Technologies Group (“ETG”), consisting of HEICO Electronic Technologies Corp. (“HEICO Electronic”) and its subsidiaries. HEICO's results of operations for the six and three months ended April 30, 2020 have been significantly affected by the COVID-19 outbreak, classified by the World Health Organization as a global pandemic in March 2020 (the “Outbreak”). The effects of the Outbreak and related actions by governments around the world to mitigate its spread have impacted the Company's employees, customers, suppliers and manufacturers. With respect to the Company’s results of operations, approximately half of HEICO’s net sales are derived from defense, space and other industrial markets including electronics, medical and telecommunications. Demand for products in that half of the Company’s business has not been fundamentally impacted and its operational results remain materially consistent with financial expectations prior to the commencement of the Outbreak. The remaining portion of HEICO’s net sales is derived from commercial aviation products and services. The Outbreak has caused significant volatility and a substantial decline in value across global economic markets. Most notably, the commercial aerospace industry has experienced an ongoing substantial decline in demand. As such, HEICO’s businesses that operate within the commercial aerospace industry have been materially impacted by the significant decline in global commercial air travel that began in March 2020. As a result of the Outbreak, HEICO has assessed various accounting estimates, including those that require consideration of forecasted financial information, in context of the unknown future impacts of the Outbreak as of April 30, 2020 and through the date of filing this Quarterly Report. The accounting estimates assessed include, but were not limited to, the Company’s allowance for doubtful accounts, inventory reserves, contingent consideration arrangements, goodwill and other long-lived assets. Based on these assessments, no material impact was recorded to HEICO’s Condensed Consolidated Statement of Operations for the six and three months ended April 30, 2020.
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Description of New Accounting Pronouncements Not yet Adopted [Text Block]	In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02, which, as amended, was codified as Accounting Standards Codification ("ASC") Topic 842, "Leases" ("ASC 842"). ASC 842 requires recognition of lease assets and lease liabilities on the balance sheet of lessees. The Company adopted ASC 842 as of November 1, 2019 using a modified retrospective transition approach with the election to apply the guidance as of the adoption date instead of at the beginning of the earliest comparative period presented. The adoption of this guidance resulted in an increase in the Company's assets and liabilities due to the recognition of right-of-use ("ROU") assets and corresponding lease liabilities for leases that are currently classified as operating leases. Upon adoption, the Company elected the package of transitional practical expedients, which allowed the Company to not reassess its prior conclusions about lease identification, lease classification, and initial direct costs. In addition, the Company elected the short-term lease practical expedient, which allows HEICO to not record an ROU asset and lease liability for any lease with a term of twelve months or less, and also elected the single component practical expedient for all asset classes, which allows the Company to include both lease and non-lease components associated with a lease as a single lease component when determining the value of the ROU asset and lease liability. The adoption of this guidance resulted in the Company recording ROU assets and corresponding lease liabilities of $63.4 million and $64.1 million, respectively, in the Company's Condensed Consolidated Balance Sheet. The adoption of ASC 842 did not have a material impact on the Company’s Condensed Consolidated Statement of Operations or Statement of Cash Flows. See Note 9, Leases, for additional information regarding the Company's accounting policy for leases and disclosures required by ASC 842.
Accounting Standards Update 2017-04 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Description of New Accounting Pronouncements Not yet Adopted [Text Block]	In January 2017, the FASB issued ASU 2017-04, "Simplifying the Test for Goodwill Impairment," which is intended to simplify the current test for goodwill impairment by eliminating the second step in which the implied value of a reporting unit is calculated when the carrying value of the reporting unit exceeds its fair value. Under ASU 2017-04, goodwill impairment should be recognized for the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. ASU 2017-04 must be applied prospectively and is effective for any annual or interim goodwill impairment test in fiscal years beginning after December 15, 2019, or in fiscal 2021 for HEICO. Early adoption is permitted. The Company is currently evaluating the effect the adoption of this guidance will have on its consolidated results of operations, financial position and cash flows.