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The charge against earnings in the period to reduce the carrying amount of real property to fair value.

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Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

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Investments in Real Estate Ventures (Details)	9 Months Ended
Investments in Real Estate Ventures (Details)	Sep. 30, 2011 USD ($)	Sep. 30, 2010 USD ($)	Dec. 31, 2010 USD ($)	Sep. 30, 2011 LaSalle Investment Company I [Member] USD ($)	Sep. 30, 2011 LaSalle Investment Company I [Member] EUR (€)	Sep. 30, 2011 LaSalle Investment Company II [Member] USD ($)	Sep. 30, 2011 LaSalle Investment Company II [Member] USD ($)	Sep. 30, 2011 Other real estate ventures [Member] USD ($)	Sep. 30, 2011 Guarantee of Indebtedness of Others [Member] USD ($)	Sep. 30, 2011 Investments in real estate ventures classified as variable interest entities [Member] USD ($)
Investments in Real Estate Ventures [Abstract]
Total investments in real estate ventures	$ 222,194,000		$ 174,578,000
Number of separate property or fund co-investments	40
Minimum ownership percentage in real estate ventures (in hundredths)	1.00%
Maximum ownership percentage in real estate ventures (in hundredths)	10.00%
Number of investment vehicles to facilitate the majority of our co-investment activity	2
Schedule of Equity Method Investments [Line Items]
Number of parallel limited partnerships which serve as our investment vehicle				4	4		2
Entity's maximum potential unfunded commitment				10,100,000	7,500,000		271,000,000	8,600,000
Unfunded capital commitments to the underlying funds for future funding of co-investments							209,700,000
Partnership ownership interest (in hundredths)				47.85%	47.85%		48.78%
Entity's share of unfunded capital commitments for future funding of co-investments							102,300,000
Percentage ownership interest held by other parties (in hundredths)				52.15%	52.15%		51.22%
Minimum expected period for vehicle to draw down on commitment (in years)				1Y	1Y		4Y
Maximum expected period for vehicle to draw down on commitment (in years)				2Y	2Y		8Y
Loss Contingencies [Line Items]
Revolving credit facility, maximum capacity						60,000,000
Entity's maximum exposure, assuming facility was fully drawn									29,300,000
Outstanding borrowings on the revolving credit facility						34,000,000
Variable Interest Entity [Line Items]
Maximum loss exposure, amount										22,500,000
Impairment [Abstract]
Impairment charges	$ 5,200,000	$ 12,600,000