Income Taxes (Details) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Income Tax Disclosure [Abstract]      
Ordinary dividends 38.00% 36.00% 35.00%
Nontaxable distributions 62.00% 47.00% 65.00%
Capital gain distributions 0.00% 17.00% 0.00%
Total 100.00% 100.00% 100.00%
Property, plant and equipment, land and real estate assets, net tax basis $ 3,100,000,000    
State and local income tax and franchise tax expense (benefit), continuing operations $ 1,400,000 $ 1,300,000 $ 1,200,000