Investment in Real Estate - Net Non-Cash Impairment Charges (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Impairment Charges [Line Items]
Total Net Impairment	$ 0	$ 1,246
Sold Operating Properties - Discontinued Operations
Impairment Charges [Line Items]
Total Net Impairment	0	1,410
Held for Use Operating Properties - Continuing Operations
Impairment Charges [Line Items]
Total Net Impairment	$ 0	$ (164)

The charge against earnings in the period to reduce the carrying amount of real property to fair value. Includes amounts in income from continuing operations and income from discontinued operations.

No definition available.

Name:	fr_ImpairmentOfRealEstateNet
Namespace Prefix:	fr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration