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Earnings Per Share ("EPS") - Additional Information (Detail) | Sep. 30, 2013 | Sep. 30, 2012
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Earnings Per Share [Abstract] |  |
Unvested restricted stock awards outstanding | 489,381 | 745,712

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- Definition Number of unvested restricted stock awards outstanding included in participating securities. + References No definition available. + Details
Name: | fr_NumberOfUnvestedRestrictedStockAwardsOutstandingIncludedInParticipatingSecurities
Namespace Prefix: | fr_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | us-gaap_EarningsPerShareAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration