Organization	12 Months Ended
Dec. 31, 2020
Organization
Organization	1. Organization Franklin Street Properties Corp. (“FSP Corp.” or the “Company”), holds, directly and indirectly, 100% of the interest in FSP Investments LLC, FSP Property Management LLC, FSP Holdings LLC and FSP Protective TRS Corp. FSP Property Management LLC provides asset management and property management services. The Company also has a non-controlling common stock interest in two corporations organized to operate as real estate investment trusts (“REIT”). Collectively, the two REITs are referred to as the “Sponsored REITs”. As of December 31, 2020, the Company owned and operated a portfolio of real estate consisting of 32 operating properties, two redevelopment properties and two managed Sponsored REITs and held one promissory note secured by a mortgage on real estate owned by a Sponsored REIT. From time-to-time, the Company may acquire real estate or make additional secured loans. The Company may also pursue, on a selective basis, the sale of its properties in order to take advantage of the value creation and demand for its properties, or for geographic or property specific reasons.

The entire disclosure for the nature of an entity's business, major products or services, principal markets including location, and the relative importance of its operations in each business and the basis for the determination, including but not limited to, assets, revenues, or earnings. For an entity that has not commenced principal operations, disclosures about the risks and uncertainties related to the activities in which the entity is currently engaged and an understanding of what those activities are being directed toward.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e5967-108592

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-URI http://asc.fasb.org/topic&trid=2134479

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