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

Number of unvested restricted stock awards outstanding included in participating securities.

No definition available.

Name:	fr_NumberOfUnvestedRestrictedStockAwardsOutstandingIncludedInParticipatingSecurities
Namespace Prefix:	fr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant