Fair value liabilities measured on recurring basis with unobservable inputs.

No definition available.

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Namespace Prefix:	fr_
Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Fair value liabilities measured on recurring basis with unobservable inputs percentage maximum.

+ References

No definition available.

+ Details

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Namespace Prefix:	fr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value liabilities measured on recurring basis with unobservable inputs percentage minimum.

+ References

No definition available.

+ Details

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Namespace Prefix:	fr_
Data Type:	num:percentItemType
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- Details

Name:	fr_QuantitativeInformationAboutLevelThreeFairValueMeasurementsAbstract
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- Definition

This element represents, the inputs and valuation technique(s) used to measure fair value and a discussion of changes in valuation techniques and related inputs, if any, during the period.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisDerivativeFinancialInstrumentsLiabilitiesValuationTechniques
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents a liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Derivatives (Details 3) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Series F Agreement [Member]	Mar. 31, 2012 Series F Agreement [Member] Long Dated Treasuries [Member]	Mar. 31, 2012 Series F Agreement [Member] Own Credit Risk [Member]	Mar. 31, 2012 Discounted Cash Flow [Member] Series F Agreement [Member]
Quantitative information about the Level 3 fair value measurements
Fair value measurements	$ 1,251	$ 1,667	$ (1,251)
Fair Value Measurements, Valuation Technique						Discounted Cash Flow
Fair Value Measurements, Unobservable Inputs				Long Dated Treasuries (A)	Own Credit Risk (B)
Fair Value Measurements, Range, Minimum Percentage			3.32%		1.51%
Fair Value Measurements, Range, Maximum Percentage			3.58%		2.85%