Equity (Details 6) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	$ 15,336	$ (4,649)	$ (8,507)
Other comprehensive income (loss) before reclassifications	(100,037)	19,042	3,408
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	3,174	2,813	2,132
Net current period other comprehensive income (loss)	(96,863)	21,855	5,540
Net current period other comprehensive income attributable to noncontrolling interests and redeemable noncontrolling interests	5,968	(1,870)	(1,682)
Balance - end of period	(75,559)	15,336	(4,649)
Interest expense
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	2,691	1,745	1,539
Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	103	537	239
Net income from equity investments in real estate and the Managed REITs
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	380	531	354
Gains and Losses on Derivative Instruments
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	(7,488)	(7,508)	(5,246)
Other comprehensive income (loss) before reclassifications	17,911	(2,793)	(4,394)
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	3,174	2,813	2,132
Net current period other comprehensive income (loss)	21,085	20	(2,262)
Net current period other comprehensive income attributable to noncontrolling interests and redeemable noncontrolling interests	0	0	0
Balance - end of period	13,597	(7,488)	(7,508)
Gains and Losses on Derivative Instruments | Interest expense
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	2,691	1,745	1,539
Gains and Losses on Derivative Instruments | Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	103	537	239
Gains and Losses on Derivative Instruments | Net income from equity investments in real estate and the Managed REITs
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	380	531	354
Foreign Currency Translation Adjustments
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	22,793	2,828	(3,299)
Other comprehensive income (loss) before reclassifications	(117,938)	21,835	7,809
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Net current period other comprehensive income (loss)	(117,938)	21,835	7,809
Net current period other comprehensive income attributable to noncontrolling interests and redeemable noncontrolling interests	5,968	(1,870)	(1,682)
Balance - end of period	(89,177)	22,793	2,828
Foreign Currency Translation Adjustments | Interest expense
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Foreign Currency Translation Adjustments | Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Foreign Currency Translation Adjustments | Net income from equity investments in real estate and the Managed REITs
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Gains and Losses on Marketable Securities
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	31	31	38
Other comprehensive income (loss) before reclassifications	(10)	0	(7)
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Net current period other comprehensive income (loss)	(10)	0	(7)
Net current period other comprehensive income attributable to noncontrolling interests and redeemable noncontrolling interests	0	0	0
Balance - end of period	21	31	31
Gains and Losses on Marketable Securities | Interest expense
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Gains and Losses on Marketable Securities | Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Gains and Losses on Marketable Securities | Net income from equity investments in real estate and the Managed REITs
Amounts reclassified from accumulated other comprehensive income (loss) to:
Amount reclassified from accumulated other comprehensive income (loss)	$ 0	$ 0