Real Property Acquisitions and Development (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Pro forma consolidated results of operations
Revenues	$ 2,268,062,000	$ 1,828,395,000
Income from continuing operations attributable to common stockholders	$ (2,079,000)	$ (59,769,000)
Income from continuing operations attributable to common stockholders per share:
Basic	$ (0.01)	$ (0.28)
Diluted	$ (0.01)	$ (0.28)