Cumulative Other Comprehensive Loss - Schedule of Reclassifications Out of Cumulative Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassifications out of cumulative other comprehensive income (Loss)
Interest expense	$ 25,111	$ 35,245	$ 82,926	$ 111,079
Gain on sale of properties	39,793	0	42,953	0
Interest and other income	(637)	$ (406)	(4,813)	$ (1,071)
Total amounts reclassified	(1,239)		(63,825)
Foreign currency translation adjustment activity
Reclassifications out of cumulative other comprehensive income (Loss)
Total amounts reclassified	0		(63,207)
Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income
Reclassifications out of cumulative other comprehensive income (Loss)
Total amounts reclassified	1,239		63,825
Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income | Foreign currency translation adjustment activity
Reclassifications out of cumulative other comprehensive income (Loss)
Gain on sale of properties	0		63,207
Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income | Realized gain on available for sale securities
Reclassifications out of cumulative other comprehensive income (Loss)
Interest and other income	0		(3,080)
Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income | Interest rate swap contracts
Reclassifications out of cumulative other comprehensive income (Loss)
Interest expense	$ 1,239		$ 3,698