Subsequent Events (Details) (Series F Preferred Stock [Member], USD $)	12 Months Ended
	Dec. 31, 2011
Subsequent Event [Line Items]
Noncontrolling Interest in Operating Partnerships	$ 50,000,000
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	6.65%
Repurchase of Equity [Member]
Subsequent Event [Line Items]
Noncontrolling Interest in Operating Partnerships	32,500,000
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount	6.65%
Payments for Repurchase of Preferred Stock and Preference Stock	$ 26,000,000