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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-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=27012166&loc=d3e187085-122770

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

Subsequent Events (Details) (USD $)	3 Months Ended					0 Months Ended		0 Months Ended
Subsequent Events (Details) (USD $)	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2014 Mortgage loan FSP Energy Tower Corp.	Jul. 11, 2014 Subsequent event Cash distribution declared	Jul. 03, 2014 Subsequent event Mortgage loan FSP Energy Tower Corp.	Jul. 03, 2014 Subsequent event Secured revolving lines of credit FSP Energy Tower Corp. Maximum
Subsequent events
Maximum amount of loan	$ 96,800,000				$ 33,000,000		$ 33,000,000
Amount agreed to pay as Advance to related party pursuant to a Sponsored REIT Loan								$ 20,000,000
Cash dividend declared per share (in dollars per share)	$ 0.19	$ 0.19	$ 0.19	$ 0.19		$ 0.19