Subsequent Events (Details Textual) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended					3 Months Ended
	May 07, 2012 IndustrialProperty	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2009	Apr. 25, 2012	Mar. 29, 2012	Jun. 30, 2012 Senior unsecured notes [Member]	Mar. 31, 2012 Senior unsecured notes [Member]	Apr. 16, 2012 2012 Notes [Member]	Apr. 25, 2012 2014 Notes [Member]	Apr. 25, 2012 2028 Notes [Member]	Apr. 25, 2012 2032 Notes [Member]
Subsequent Events (Textual) [Abstract]
Amount of payment from senior unsecured notes maturing in future period									$ 61,829
Amount of repurchased and retired senior unsecured notes maturing in future period										9,000	55,525	22,400
Gain (Loss) from Retirement of Debt		1	(1,026)					1
Subsequent Events (Textual Other) [Abstract]
Maximum aggregate cash tender offer price						100,000
Number of industrial property sold	4
Gross proceed from the sale of industrial properties	3,750
Number of industrial property acquired	0
Amount of consideration for tender offer					88,922
Period of carry back net operating losses				up to 5 years
Received refund from IRS due to the tax liquidation of the taxable REIT subsidiaries				40,418
Refund claims in excess required by statute to review on behalf of joint committee on taxation		$ 2,000