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Concentrations of Credit Risk and Major Customers (Details) - Accounts Receivable [Member]	12 Months Ended
	Mar. 31, 2020		Mar. 31, 2019
Three largest receivable balances	72.50%		78.20%
Customer A [Member]
Three largest receivable balances	47.40%		61.10%
Customer B [Member]
Three largest receivable balances		[1]	10.20%
Customer C [Member]
Three largest receivable balances	18.40%		6.90%
Customer D [Member]
Three largest receivable balances	6.70%			[1]
[1] not among the top three receivable balances as of respective year end.

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- Definition

Percentage of loans receivable during the period.

+ References

No definition available.

+ Details

Name:	hiho_LoansReceivablePercentage
Namespace Prefix:	hiho_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_AccountsReceivableMember
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Data Type:	na
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- Details

Name:	srt_MajorCustomersAxis=hiho_CustomerAMember
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Data Type:	na
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X

- Details

Name:	srt_MajorCustomersAxis=hiho_CustomerBMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	srt_MajorCustomersAxis=hiho_CustomerCMember
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Data Type:	na
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X

- Details

Name:	srt_MajorCustomersAxis=hiho_CustomerDMember
Namespace Prefix:
Data Type:	na
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