ACQUISITIONS ACQUISITIONS (Fair Value of Acquired Assets) (Details) - USD ($) $ in Thousands	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017
Assets acquired:
Goodwill	$ 1,268,703	$ 1,114,832	$ 1,081,306
HEICO Electronic [Member] | AAT [Member]
Assets acquired:
Goodwill	157,901
Inventories	8,306
Accounts receivable	6,115
Property, plant and equipment	1,893
Other assets	208
Total assets acquired, excluding cash	333,423
Liabilities assumed:
Accounts payable	1,299
Accrued expenses	1,151
Total liabilities assumed	2,450
Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	330,973
HEICO Electronic [Member] | AAT [Member] | Trade Names [Member]
Assets acquired:
Identifiable intangible assets, indefinite-lived	20,000
HEICO Electronic [Member] | AAT [Member] | Customer Relationships [Member]
Assets acquired:
Identifiable intangible assets, finite-lived	100,000
HEICO Electronic [Member] | AAT [Member] | Intellectual Property [Member]
Assets acquired:
Identifiable intangible assets, finite-lived	$ 39,000