Amount of consideration transferred for the purchase of real estate.

No definition available.

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- Definition

The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2443-110228

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow from the acquisition of residential property intended to generate income for the owner.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 10
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- Definition

Cash received for the sale of real estate that is not part of an investing activity during the current period.

+ 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
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-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Details

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Balance Type:
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- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=sqft_WatermanPlazaMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=sqft_GardenGatewayMember
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- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=sqft_ModelHomeMember
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Balance Type:
Period Type:

- Details

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- Details

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Note 3 - Recent Real Estate Transactions (Details Textual)					3 Months Ended
	Feb. 19, 2021 USD ($)	Jan. 28, 2021 USD ($)	Mar. 13, 2020 USD ($)	Feb. 05, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Notes Payable, Total					$ 0		$ 7,500,086
Discontinued Operations, Disposed of by Sale [Member]
Proceeds from Sale of Real Estate, Total					4,900,000	$ 2,800,000
Gain (Loss) on Sale of Properties					$ 400,000	$ 200,000
Number of Real Estate Properties					12	8
Waterman Plaza [Member] \| Discontinued Operations, Disposed of by Sale [Member]
Proceeds from Sale of Real Estate, Total		$ 3,500,000
Gain (Loss) on Sale of Properties		$ (200,000)
Garden Gateway [Member] \| Discontinued Operations, Disposed of by Sale [Member]
Proceeds from Sale of Real Estate, Total	$ 11,200,000
Gain (Loss) on Sale of Properties	$ (1,400,000)
Model Home [Member]
Number of Real Estate Properties					0	10
Real Estate Property, Consideration Transferred, Total						$ 3,600,000
Payments to Acquire Residential Real Estate						1,100,000
Model Home [Member] \| Mortgage Notes [Member]
Notes Payable, Total						$ 2,500,000
Centennial Tech Center [Member] \| Discontinued Operations, Disposed of by Sale [Member]
Proceeds from Sale of Real Estate, Total				$ 15,000,000.0
Gain (Loss) on Sale of Properties				$ (900,000)
Union Terrace [Member] \| Discontinued Operations, Disposed of by Sale [Member]
Proceeds from Sale of Real Estate, Total			$ 11,300,000
Gain (Loss) on Sale of Properties			$ 690,000