Real Estate - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Real Estate Properties [Line Items]
Gains on acquisitions and dispositions of investments in real estate, net	$ 61,035	$ 520	$ 399,880	$ 268,291
Europe [Member]
Real Estate Properties [Line Items]
Gains on acquisitions and dispositions of investments in real estate, net			1,800
Japan [Member]
Real Estate Properties [Line Items]
Gains on acquisitions and dispositions of investments in real estate, net			337,900
Gain related to the contribution of one property to our new venture			$ 56,900