Debt - Debt Summary (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	4.20%	4.40%
Amount Outstanding	$ 9,011,216	$ 11,790,794
Credit Facilities [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	1.20%	1.50%
Amount Outstanding	725,483	888,966
Senior notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	4.50%	5.60%
Amount Outstanding	5,357,933	5,223,136
Exchangeable senior notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	3.30%	4.60%
Amount Outstanding	438,481	876,884
Secured mortgage debt [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	5.60%	4.00%
Amount Outstanding	1,696,597	3,625,908
Secured mortgage debt of consolidated entities [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	4.70%	4.40%
Amount Outstanding	239,992	450,923
Other debt of consolidated entities [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate		4.80%
Amount Outstanding		67,749
Term Loan [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	1.70%	1.70%
Amount Outstanding	535,908	639,636
Other debt [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Weighted Average Interest Rate	6.20%	6.20%
Amount Outstanding	$ 16,822	$ 17,592