Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)
In Thousands, except Share data, unless otherwise specified
Mar. 31, 2012
Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]    
Accumulated depreciation on buildings and improvements $ 253,900 $ 238,688
Unearned income on real estate assets under direct financing leases 12,870 13,342
Accumulated amortization on acquired intangible lease assets 136,624 128,544
Allowance for doubtful accounts on rents and tenant receivables 352 547
Accumulated amortization on deferred financing costs 19,256 17,751
Accumulated amortization on acquired below market lease intangibles $ 45,626 $ 42,880
Preferred stock, par value $ 0.01 $ 0.01
Preferred stock, shares authorized 10,000,000 10,000,000
Preferred stock, shares issued      
Preferred stock, shares outstanding      
Common stock, par value $ 0.01 $ 0.01
Common stock, shares authorized 240,000,000 240,000,000
Common stock, shares issued 210,164,068 210,151,692
Common stock, shares outstanding 210,164,068 210,151,692