Name:	fsp_IncomeTaxReconciliationRevisedTexasFranchiseTax
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Represents the maximum ownership in all Taxable REIT Subsidiaries that can be held by the entity as a percentage of its assets value to maintain its REIT status.

No definition available.

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Represents the maximum ownership in all Taxable REIT Subsidiaries that can be held by the entity as a percentage of its assets value when considered together with other non-real estate assets to maintain its REIT status.

No definition available.

Name:	fsp_MaximumOwnershipInAllTaxableREITSubsidiariesAsPercentageOfAssetsOfEntityToMaintainREITStatusIncludingOtherNonRealEstateAssets
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Represents the maximum ownership that the entity can hold as a percentage of the voting power or value of the securities of each issuer which is not a REIT or Taxable REIT Subsidiary.

No definition available.

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- References

No definition available.

Name:	fsp_OperatingLossCarryforwardAbstract
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Represents the period after which the net operating losses expire.

No definition available.

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Represents the period of statute of limitations for the entity's income tax returns, that remain subject to examination.

No definition available.

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Data Type:	xbrli:durationItemType
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Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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- References

No definition available.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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- References

No definition available.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority noncontrolling interest income (loss), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, increase (decrease) in enacted tax rate, prior year income taxes, increase (decrease) in deferred tax asset valuation allowance, and other adjustments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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