Other Assets (Details)	1 Months Ended
	Jun. 30, 2012 USD ($)	Jun. 28, 2012 USD ($)	Jun. 28, 2012 GBP (£)	Dec. 31, 2011 USD ($)
Other assets, details:
Straight-line rent assets, net of allowance of $34,822 and $34,457, respectively	$ 287,590,000			$ 266,620,000
Allowance on straight-line rent assets	34,822,000			34,457,000
Marketable debt securities	214,860,000
Leasing costs, net	93,524,000			92,288,000
Deferred financing costs, net	38,139,000			35,649,000
Goodwill	50,346,000			50,346,000
Marketable equity securities	17,396,000			17,053,000
Other	33,137,000			23,502,000
Total other assets	734,992,000			485,458,000
Adjusted cost basis of marketable equity securities	17,100,000			17,100,000
Additions related to accrued interest receivable	5,400,000			5,400,000
Interest rate on senior unsecured notes acquired	12.25%
Yield to maturity	12.50%
Marketable debt security, par value, discounted		214,900,000	136,800,000
Marketable debt security, par value			£ 138,500,000