Debt Mortgage Notes Payable (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				1 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 Credit enhanced debt [Member]	May 08, 2014 Secured Debt [Member]	Mar. 31, 2014 Secured Debt [Member]
Debt Instrument [Line Items]
Mortgage notes payable	$ 5,167,626		$ 5,174,166	$ 700,500
Repayments Of Mortgage Notes Payable	$ 3,034	$ 3,244			$ 3,100	$ 3,000
Debt Instrument, Maturity Date	May 01, 2061
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.04%
Interest rate range to maximum	7.25%
Weighted Average Mortgage Debt Interest Rate	4.22%