Subsequent Events - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended	1 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Property Parcels	Jun. 30, 2012 Property	Dec. 31, 2012 Property	Aug. 02, 2013 Subsequent Event [Member] Property Parcels	Jul. 19, 2013 Subsequent Event [Member]	Jul. 18, 2013 Subsequent Event [Member]
Subsequent Event [Line Items]
Paid off and retired a secured mortgage loan			$ 33,175,000	$ 18,273,000		$ 14,046,000
Depositary shares redeemed			4,000,000			2,000,000
Portion of preferred stock	0.0001		0.0001					0.1000
Dividend rate per share			7.25%			7.25%
Par value of each depositary share	$ 0.01		$ 0.01					$ 0.01
Redemption price per share	$ 25.00		$ 25.00					$ 25.00
Payments for repurchase of redeemable preferred stock			100,000,000	0		50,000
Line of credit facility, maximum borrowing capacity							625,000
Line of credit facility, increase, additional borrowings						825,000
Line of credit facility, interest rate description						145
Number of certain rating agencies						1
Number of years of extension of line of credit facility at election						1 year
Number of industrial properties sold			12	7	28	3
Number of land parcels sold			2			1
Proceeds from sale of industrial properties and land parcel						6,102,000
Write-off of Unamortized Settlement Amounts of Interest Rate Protection Agreements	$ (4,436,000)	$ (6,223,000)	$ (5,586,000)	$ (6,222,000)