Represents the high end of the range of percentage points added to the base rate to compute the variable rate on debt instrument.

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- Definition

Represents the low end of the range of percentage points added to the base rate to compute the variable rate on debt instrument.

+ Details

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- Definition

Represents the minimum operating cash balance that is required to be maintained under the financial covenant.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Represents the period from the maturity date of the debt for which the debt facility can be extended.

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- Definition

Represents the minimum LIBOR rate that may be charged on a debt agreement.

+ Details

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- Definition

The maximum fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ Details

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- Definition

The minimum fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ Details

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Namespace Prefix:	fsp
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- Definition

Represents the initial term of the borrowing, from inception to maturity.

+ Details

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Period Type:	duration

- Definition

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ Details

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- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

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- Definition

Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of debt outstanding by type or by instrument at that time.

+ Details

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- Definition

Fixed interest rate related to the interest rate derivative.

+ Details

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ Details

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Period Type:	duration

- Definition

Increase for additional borrowings on the credit facility during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 4
-Section 08
-Paragraph f

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

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- Definition

The effective interest rate at the end of the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 22
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

The effective interest rate during the reporting period.

+ References

+ Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 129
-Paragraph 2, 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 22
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow to repay long-term debt that is not secured by collateral. Excludes repayments of tax exempt unsecured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3291-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 18
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 20
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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Bank note payable and term note payable (Details) (USD $)	6 Months Ended		6 Months Ended		12 Months Ended		12 Months Ended		6 Months Ended	1 Months Ended	6 Months Ended			6 Months Ended				6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Revolver	Jun. 30, 2010 Revolver	Dec. 31, 2010 Revolver	Feb. 22, 2011 Revolver	Dec. 31, 2010 Revolver LIBOR	Feb. 22, 2011 Revolver LIBOR	Jun. 30, 2011 Revolver Bank's base rate	May 31, 2011 New Revolver	Jun. 30, 2011 New Revolver	May 19, 2011 New Revolver	Feb. 22, 2011 New Revolver	Jun. 30, 2011 New Revolver LIBOR	Jun. 30, 2011 New Revolver Bank's base rate	Jun. 30, 2011 Term Loan	Dec. 31, 2010 Term Loan	Jun. 30, 2011 Term Loan LIBOR	Feb. 22, 2011 Term Loan LIBOR
Bank note and term note payable
Total available						$ 250,000,000						$ 600,000,000	$ 500,000,000
Additional borrowing capacity allowed by exercising an accordion feature										100,000,000
Repayment	74,850,000															75,000,000
Financial covenant, minimum operating cash					1,500,000												1,500,000
Extension available on debt (in years)											1
Basis spread on variable rate, low end of range (as a percent)														1.85%	0.85%
Basis spread on variable rate, high end of range (as a percent)														3.00%	2.00%
Basis spread on variable rate, end of period (as a percent)								1.00%						2.10%	1.10%				2.00%
Facility fee, low end of range (as a percent)											0.30%
Facility fee, high end of range (as a percent)											0.50%
Facility fee, end of period (as a percent)											0.40%
Overall rate (basis spread plus variable rate), end of period (as a percent)														2.29%	4.35%
Borrowings outstanding	$ 345,000,000	$ 209,968,000			$ 209,968,000						$ 345,000,000
Weighted average interest rate, end of period (as a percent)					1.26%						2.33%
Weighted average rate interest rate, during period (as a percent)			2.03%	1.29%	1.33%						2.03%
Variable base rate							LIBOR		Bank's prime rate					LIBOR	Bank's base rate			LIBOR
Minimum interest rate (as as percent)																		2.00%
Initial term of the borrowing (in years)																3
Fixed interest rate pursuant to interest rate swap contract (as a percent)																		5.84%