Cash Flow Information (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Real Estate Properties
Deferred acquisition fees payable (Note 3, 4)	$ 0	$ 989
Build-to-suit construction costs incurred but unpaid	7,679	0
Non-recourse mortgage loans assumed on acquisition (Note 11)	8,995	0
First quarter distributions declared	52,041	50,207	51,570
In-place lease
Real Estate Properties
Reclassification to real estate	1,795	464
Below-market rent
Real Estate Properties
Reclassification from real estate	(3,425)	0
Real estate
Real Estate Properties
Reclassification to real estate	1,630	35,395
Reclassification from real estate	0	(464)
Operating real estate
Real Estate Properties
Reclassification to real estate	14,929	0
Real estate under construction
Real Estate Properties
Reclassification from real estate	$ (14,929)	$ (35,395)