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v3.21.2

Concentrations of Credit Risk and Major Customers (Details) | 12 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020 | Mar. 31, 2019
Concentrations of Credit Risk and Major Customers (Details) [Line Items] |  |  |
Customers accounting percentage | 10.00% |  |
Accounts Receivable [Member] |  |  |
Concentrations of Credit Risk and Major Customers (Details) [Line Items] |  |  |
Customers accounting percentage | 10.00% | 10.00% |
Total revenue [Member] |  |  |
Concentrations of Credit Risk and Major Customers (Details) [Line Items] |  |  |
Customers accounting percentage | 10.00% | 10.00% | 10.00%

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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator), this concept represents the concentration percentage derived from the division. + References No definition available. + Details
Name: | hiho_ConcentrationRiskThresholdPercentage
Namespace Prefix: | hiho_
Data Type: | dtr:percentItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | hiho_ConcentrationsofCreditRiskandMajorCustomersDetailsLineItems
Namespace Prefix: | hiho_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_AccountsReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_SalesRevenueNetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |