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Concentrations of Credit Risk and Major Customers (Details) - Accounts Receivable [Member]	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Three largest receivable balances	78.20%	72.90%
Customer A [Member]
Three largest receivable balances	61.10%	54.90%
Customer B [Member]
Three largest receivable balances	10.20%	9.00%
Customer C [Member]
Three largest receivable balances	6.90%	9.00%

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- Definition

Percentage of loans receivable during the period.

+ References

No definition available.

+ Details

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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
Namespace Prefix:
Data Type:	na
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- Details

Name:	srt_MajorCustomersAxis=hiho_CustomerAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_MajorCustomersAxis=hiho_CustomerBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_MajorCustomersAxis=hiho_CustomerCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: