Acquisitions (Details 1) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2009
Proforma information for the Company as if the acquisition of properties
Revenues and Other	$ 13,780	$ 10,717
Net Income (Loss)	3,364	(477)
Preferred Stock Dividends	76	83
Income (Loss) Attributable to Common Stock	$ 3,288	$ (560)
Net Income (Loss) per Common Share - Basic	$ 8.62	$ (1.48)
Net Income (Loss) per Common Share - Diluted	$ 8.52	$ (1.48)