Name:	fsp_MaximumNumberOfDaysToExtendClosingDate
Namespace Prefix:	fsp_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

Represents the minimum number of days the other party must give in order to extend the closing date of the sale of properties.

No definition available.

Name:	fsp_MinimumNumberOfDaysNoticeOtherPartyMustGiveToExtendClosingDate
Namespace Prefix:	fsp_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

Represents the number of office properties to be sold.

No definition available.

Name:	fsp_NumberOfOfficePropertiesToBeSold
Namespace Prefix:	fsp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of times each the buyer and seller have to extend the closing date of the sale of properties.

No definition available.

Name:	fsp_NumberOfTimesBuyerAndSellerHaveRightsToExtendClosingDate
Namespace Prefix:	fsp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Area of a real estate property.

No definition available.

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

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

The cash inflow from the sale of formerly productive land held for sale, anything permanently fixed to it, including buildings, structures on it, and so forth.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromSaleOfPropertyHeldForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.