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Fair Value of Financial Instruments - Additional Information (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2025 | Dec. 31, 2024
Sandoval Flats [Member] |  |
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] |  |
Unrealized gains (losses) from property loan held for sale | $ 0 | $ 0
Fair Value, Inputs, Level 3 [Member] | Governmental Issuer Loan [Member] |  |
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] |  |
Available for Sale Security and Property Loan Receivable, Maximum Exposure | 162,500,000 | 226,700,000
Fair Value, Inputs, Level 3 [Member] | Taxable Governmental Issuer Loan [Member] |  |
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] |  |
Available for Sale Security and Property Loan Receivable, Maximum Exposure | $ 22,800,000 | $ 13,900,000

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- Definition Available for Sale Security and Property Loan Receivable, Maximum Exposure - This represents the maximum exposure to loss related to the Available for Sale Securities and Property Loan Receivables. + References No definition available. + Details
Name: | ghi_AvailableForSaleSecurityAndPropertyLoanReceivableMaximumExposure
Namespace Prefix: | ghi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Unrealized gains (losses) from property loan held for sale. + References No definition available. + Details
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Namespace Prefix: | ghi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |