REDEEMABLE NONCONTROLLING INTERESTS (Details Textuals) $ in Millions	Oct. 31, 2019 USD ($)
Temporary Equity Disclosure [Abstract]
Aggregate Redemption Amount Puttable	$ 106.7
Potential Redemption Amount Payable	$ 47.8

The aggregate redemption amount currently puttable as of the Balance Sheet date, including the aggregate redemption amount of any put rights becoming puttable within twelve months from the Balance Sheet date.

No definition available.

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