Financial Instruments and Fair Value Measurements - Carrying Amounts and Estimated Fair Value of Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Debt:
Carrying Value of Debt	$ 9,011,216	$ 11,790,794
Fair Value of Debt	9,586,791	12,719,075
Credit Facilities [Member]
Debt:
Carrying Value of Debt	725,483	888,966
Fair Value of Debt	725,679	893,577
Senior notes [Member]
Debt:
Carrying Value of Debt	5,357,933	5,223,136
Fair Value of Debt	5,698,864	5,867,124
Exchangeable senior notes [Member]
Debt:
Carrying Value of Debt	438,481	876,884
Fair Value of Debt	514,381	1,007,236
Secured mortgage debt [Member]
Debt:
Carrying Value of Debt	1,696,597	3,625,908
Fair Value of Debt	1,840,829	3,765,556
Secured mortgage debt of consolidated entities [Member]
Debt:
Carrying Value of Debt	239,992	450,923
Fair Value of Debt	246,324	455,880
Other debt of consolidated entities [Member]
Debt:
Carrying Value of Debt		67,749
Fair Value of Debt		68,751
Term loan and other debt [Member]
Debt:
Carrying Value of Debt	552,730	657,228
Fair Value of Debt	$ 560,714	$ 660,951