Document and Entity Information
May 28, 2020
Document and Entity Information [Abstract]  
Document Type 8-K
Document Period End Date May 28, 2020
Entity File Number 001-32470
Entity Registrant Name Franklin Street Properties Corp.
Entity Incorporation, State or Country Code MD
Entity Tax Identification Number 04-3578653
Entity Address, Address Line One 401 Edgewater Place
Entity Address, Adress Line Two Suite 200
Entity Address, State or Province MA
Entity Address, City or Town Wakefield
Entity Address, Postal Zip Code 01880
City Area Code 781
Local Phone Number 557-1300
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock, $.0001 par value per share
Trading Symbol FSP
Security Exchange Name NYSE
Entity Emerging Growth Company false
Entity Central Index Key 0001031316
Amendment Flag false