Debt Mortgage Notes Payable (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Mortgage notes payable	$ 5,090,960,000	$ 5,174,166,000
Repayments Of Long-term Debt	72,700,000
Debt Instrument, Maturity Date	May 01, 2061
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.03%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.25%
Weighted Average Mortgage Debt Interest Rate	4.24%
Credit enhanced debt [Member]
Debt Instrument [Line Items]
Mortgage notes payable	$ 700,500,000