Annual report pursuant to Section 13 and 15(d)

Properties, net (Details)

v3.3.1.900
Properties, net (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Properties        
Gross $ 4,158,616 $ 4,014,336 $ 3,811,950 $ 3,859,960
Operating properties, net 2,920,529 2,751,488    
Operating properties, net [Member]        
Properties        
Less: accumulated depreciation (700,363) (703,083)    
Operating properties, net [Member] | Land [Member]        
Properties        
Gross 463,305 439,355    
Operating properties, net [Member] | Buildings and improvements [Member]        
Properties        
Gross $ 3,157,587 $ 3,015,216