The gain or loss on sale of real estate, per share, net of incentive fee.

No definition available.

Name:	hmg_GainOrLossOnRealEstatePerShare
Namespace Prefix:	hmg_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents increase in percentage of extension permit.

+ References

No definition available.

+ Details

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Namespace Prefix:	hmg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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Balance Type:	na
Period Type:	duration

- Definition

Area of land held.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	instant

- Definition

The amount of cash deposited in financial institutions as of the balance sheet date that is insured by the Federal Deposit Insurance Corporation.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of cash as of the balance sheet date that is not insured by the Federal Deposit Insurance Corporation.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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Period Type:	instant

- Definition

Amount of gain on the sale of property that does not qualify for gain recognition as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the applicable amount of income taxes or benefit realized on the gain (loss) on sale of properties during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 974
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-15.(a)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=6875705&loc=d3e641549-123027

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Balance Type:	debit
Period Type:	duration

- Definition

Description of noncontrolling interest which might include background information, terms of the ownership arrangement, and type and terms of equity interest owned by the noncontrolling interest holders.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the payments that the lessee is obligated to make or can be required to make in connection with a property under the terms of an agreement classified as an operating lease, excluding contingent rentals and a guarantee by the lessee of the lessor's debt and the lessee's obligation to pay (apart from the rental payments) executory costs such as insurance, maintenance, and taxes.

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-SubTopic 20
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-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=82846649&loc=d3e38371-112697

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expense charged against earnings to allocate the cost of tangible and intangible assets over their remaining economic lives, classified as other.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 1
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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow associated with the sale of other real estate not otherwise defined in the taxonomy.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Useful life on which depreciation was computed for entities with a substantial portion of business acquiring and holding investment real estate, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28(Column I))
-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, the maximum amount borrowed at any time during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=us-gaap_CollateralPledgedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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- Details

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- Details

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- Details

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DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details Textual)	1 Months Ended		12 Months Ended
	Feb. 28, 2018 USD ($) $ / shares	Jul. 31, 2017 USD ($) ft²	Dec. 31, 2018 USD ($) a shares	Dec. 31, 2017 USD ($) shares	Sep. 14, 2014 a
SEC Schedule III, Real Estate and Accumulated Depreciation, Life Used for Depreciation			39 years 6 months
Depreciation expense for the corporate offices			$ 15,000	$ 15,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount \| shares			1,600	12,500
Percentage Of Increase In Extention Permit			5.00%
Cash, Uninsured Amount			$ 0	$ 52,000
Cash, FDIC Insured Amount			250,000
Operating Leases, Rent Expense, Minimum Rentals			58,344
Short-term Debt, Maximum Amount Outstanding During Period				0
Gain or loss on real estate per share \| $ / shares	$ 5.40
Gain (Loss) on Sale of Properties, Applicable Income Taxes	$ 5,500,000		(5,473,887)	0
US Treasury Securities [Member]
Debt Securities, Trading, Restricted			9,900,000	0
Collateral Pledged [Member]
Debt Securities, Trading, Restricted			$ 0	$ 267,000
Cii [Member]
Noncontrolling Interest, Ownership Percentage by Parent			95.00%
Area of Land \| ft²		20,000
Proceeds from Sale of Other Real Estate		$ 44,000
Deferred Gain on Sale of Property		$ 10,000
Courtland Investment Inc [Member]
Noncontrolling Interest, Ownership Percentage by Parent			95.00%
260 River Corp [Member]
Noncontrolling Interest, Ownership Percentage by Parent			70.00%
Area of Land \| a			5.4
Baleen Associates Inc [Member]
Noncontrolling Interest, Ownership Percentage by Parent			50.00%
HMG Atlanta LLC [Member]
Noncontrolling Interest, Ownership Percentage by Parent			1.50%
HMG Orlando LLC [Member]
Area of Land \| a					9.5
HMG Bayshore LLC [Member]
Noncontrolling Interest, Description			This is a wholly owned Florida limited liability company which owns an investment in an entity which invests in mortgages secured by real estate.