Note 4 - Real Estate Assets (Details Textual)	9 Months Ended	12 Months Ended
Sep. 30, 2021 ft² a	Dec. 31, 2016
Number of States Real Estate Property is Located	4
Number of Limited Partnerships in which Company is Sole General Partner		1
Number of Limited Liability Companies	2	5
Number of Real Estate Properties Held for Sale	1
NetREIT Palm Self-Storage LP [Member]
Noncontrolling Interest, Ownership Percentage by Parent	61.30%
Genesis Plaza [Member]
Real Estate Property, Number of Tenants-in-common Owning the Property	2
Percentage Beneficial Ownership in Property	76.40%
Genesis Plaza [Member] \| Tenant-in-common One [Member]
Percentage Ownership in Property	57.00%
Genesis Plaza [Member] \| Tenant-in-common Two [Member]
Percentage Ownership in Property	43.00%
Office/Industrial Properties [Member]
Area of Real Estate Property (Square Foot) \| a	724,000
Office/Industrial Properties [Member] \| Industrial Buildings [Member]
Number of Real Estate Properties	1
Office/Industrial Properties [Member] \| Office Buildings [Member]
Number of Real Estate Properties	7
Retail Properties [Member]
Number of Real Estate Properties	4
Area of Real Estate Property (Square Foot)	121,000
Model Home [Member]
Number of Real Estate Properties	85
Area of Real Estate Property (Square Foot)	276,000
Number of Limited Partnerships in which Company is Sole General Partner	6
Number of Limited Liability Companies	1
Number of Real Estate Properties Held for Sale	3
COLORADO
Number of Real Estate Properties	5
NORTH DAKOTA
Number of Real Estate Properties	4
SOUTH DAKOTA
Number of Real Estate Properties	2
TEXAS
Number of Real Estate Properties	1

Represents the number of limited liability companies.

No definition available.

Name:	sqft_NumberOfLimitedLiabilityCompanies
Namespace Prefix:	sqft_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of limited partnerships in which the Company is the sole general partner.

+ References

No definition available.

+ Details

Name:	sqft_NumberOfLimitedPartnershipsInWhichCompanyIsSoleGeneralPartner
Namespace Prefix:	sqft_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of real estate properties held for sale.

+ References

No definition available.

+ Details

Name:	sqft_NumberOfRealEstatePropertiesHeldForSale
Namespace Prefix:	sqft_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of states in which real estate property is located.

+ References

No definition available.

+ Details

Name:	sqft_NumberOfStatesRealEstatePropertyIsLocated
Namespace Prefix:	sqft_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the aggregate percentage ownership by the reporting entity in the specified property.

+ References

No definition available.

+ Details

Name:	sqft_PercentageBeneficialOwnershipInProperty
Namespace Prefix:	sqft_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of the property owned.

+ References

No definition available.

+ Details

Name:	sqft_PercentageOwnershipInProperty
Namespace Prefix:	sqft_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of tenants-in-common that own the specified real estate properties.

+ References

No definition available.

+ Details

Name:	sqft_RealEstatePropertyNumberOfTenantsInCommonOwningTheProperty
Namespace Prefix:	sqft_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_OwnershipAxis=sqft_NetREITPalmSelfStorageLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=sqft_GenesisPlazaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=sqft_TenantInCommonOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=sqft_TenantInCommonTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=sqft_OfficeIndustrialPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=sqft_IndustrialBuildingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=sqft_OfficeBuildingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=sqft_RetailPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=sqft_ModelHomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_CO
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_ND
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_SD
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_TX
Namespace Prefix:
Data Type:	na
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Period Type: