Stock-Based Compensation and Equity (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	$ 17,443	$ (9,414)	$ 15,336	$ (4,649)
Other comprehensive income before reclassifications	(4,596)	6,394	(4,034)	(674)
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	1,234	780	2,438	1,271
Net current period other comprehensive income	(3,362)	7,174	(1,596)	597
Net current period other comprehensive (income) loss attributable to noncontrolling interests and redeemable noncontrolling interest	134	(744)	475	1,068
Balance - end of period	14,215	(2,984)	14,215	(2,984)
Interest expense
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	634	441	1,335	875
Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	440	23	824	(24)
Net income from equity investments in real estate and the Managed REITs
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	160	316	279	420
Realized and Unrealized Gains (Losses) on Derivative Instruments
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	(10,285)	(4,333)	(7,488)	(7,508)
Other comprehensive income before reclassifications	(3,001)	1,300	(7,002)	3,984
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	1,234	780	2,438	1,271
Net current period other comprehensive income	(1,767)	2,080	(4,564)	5,255
Net current period other comprehensive (income) loss attributable to noncontrolling interests and redeemable noncontrolling interest	0	0	0	0
Balance - end of period	(12,052)	(2,253)	(12,052)	(2,253)
Realized and Unrealized Gains (Losses) on Derivative Instruments | Interest expense
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	634	441	1,335	875
Realized and Unrealized Gains (Losses) on Derivative Instruments | Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	440	23	824	(24)
Realized and Unrealized Gains (Losses) on Derivative Instruments | Net income from equity investments in real estate and the Managed REITs
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	160	316	279	420
Foreign Currency Translation Adjustments
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	27,680	(5,112)	22,793	2,828
Other comprehensive income before reclassifications	(1,590)	5,094	2,956	(4,658)
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Net current period other comprehensive income	(1,590)	5,094	2,956	(4,658)
Net current period other comprehensive (income) loss attributable to noncontrolling interests and redeemable noncontrolling interest	134	(744)	475	1,068
Balance - end of period	26,224	(762)	26,224	(762)
Foreign Currency Translation Adjustments | Interest expense
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Foreign Currency Translation Adjustments | Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	0	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 to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Unrealized Appreciation (Depreciation) on Marketable Securities
Reconciliation Of Accumulated Comprehensive Income
Balance - beginning of period	48	31	31	31
Other comprehensive income before reclassifications	(5)	0	12	0
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Net current period other comprehensive income	(5)	0	12	0
Net current period other comprehensive (income) loss attributable to noncontrolling interests and redeemable noncontrolling interest	0	0	0	0
Balance - end of period	43	31	43	31
Unrealized Appreciation (Depreciation) on Marketable Securities | Interest expense
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Unrealized Appreciation (Depreciation) on Marketable Securities | Other income and (expenses)
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Unrealized Appreciation (Depreciation) on Marketable Securities | Net income from equity investments in real estate and the Managed REITs
Amounts reclassified from accumulated other comprehensive income to:
Amount reclassified from accumulated other comprehensive income (loss)	$ 0	$ 0	$ 0	$ 0