SELECTED FINANCIAL STATEMENT INFORMATION (Details Textuals) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2021	Apr. 30, 2020	Oct. 31, 2020
Selected Financial Statement Information (Details) [Abstract]
Accrued customer rebates and credits	$ 15.3		$ 15.3		$ 15.8
Total customer rebates and credits deducted within net sales	$ 1.0	$ 1.7	$ 1.8	$ 3.8

Carrying value as of the balance sheet date of accrued customer rebates and credits.

No definition available.

Name:	hei_AccruedCustomerRebatesAndCredits
Namespace Prefix:	hei_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant